Elodie Rougier

Winnie Mar

Valeria Della Valle

Baptiste Morel

Sabine Irtan

Etienne Audureau

Aurore Coulomb-L'hermine

Hubert Ducou Le Pointe

Eléonore Blondiaux
email: eleonore.blondiaux@aphp.fr

Added value of MRI for the diagnosis of adnexal torsion in children and adolescents after inconclusive ultrasound examination

Keywords: Adnexal torsion, Ovarian torsion, Child, Ultrasonography, Magnetic resonance imaging (MRI) Adnexal torsion AUC: area under the receiver operating curve MRI: Magnetic resonance imaging OR: odds ratio ROC: receiver operating curve SD: standard deviation

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Adnexal torsion (AT) is a rare condition in the pediatric population with an estimated incidence of 4.9/100000 females aged from 1 year to 20 years [START_REF] Riccabona | European Society of Paediatric Radiology abdominal imaging task force recommendations in paediatric uroradiology, part IX: Imaging in anorectal and cloacal malformation, imaging in childhood ovarian torsion, and efforts in standardising paediatric uroradiology terminology[END_REF]. Early diagnosis of AT is essential because delayed identification may lead to ovarian hemorrhagic infarction and necrosis of adnexal structures, which may impair future fertility [START_REF] Ngo | Pediatric ovarian torsion: a pictorial review[END_REF]. Generally, ultrasound is the initial investigation when clinical findings are consistent with AT [START_REF] Bronstein | A meta-analysis of B-mode ultrasound, Doppler ultrasound, and computed tomography to diagnose pediatric ovarian torsion[END_REF]. In adults, ultrasound may demonstrate key signs of AT such as an enlarged ovary, abnormal flow on color Doppler ultrasound, peripherally displaced follicles, an adnexal mass that may trigger AT, a thickened ovarian tube and a whirlpool sign [START_REF] Chang | Pearls and pitfalls in diagnosis of ovarian torsion[END_REF][START_REF] Mashiach | Sonographic diagnosis of ovarian torsion: accuracy and predictive factors[END_REF]. Ultrasound findings in children with AT have also been described [START_REF] Linam | US findings of adnexal torsion in children and adolescents: size really does matter[END_REF][START_REF] Servaes | Sonographic findings of ovarian torsion in children[END_REF], with overall high sensitivity (90.9%) but relatively low specificity (68.7%) and accuracy (80%) [START_REF] Jourjon | Analysis of clinical and ultrasound determinants of adnexal torsion in children and adolescents[END_REF]. In few children, ultrasound examination cannot exclude torsion with certainty mostly because ultrasound findings in AT overlap with those of simple hemorrhagic cyst that may mimic AT. Moreover, in children with a large ovarian mass stretching the ovarian parenchyma, the usual ovarian signs of AT are missing. Therefore, with an inconclusive initial ultrasound examination, additional strategies are needed to improve the diagnostic accuracy and decrease the rate of diagnostic laparoscopy, because the latter can be associated with substantial morbidity.

In studies of adults with suspected AT, magnetic resonance imaging (MRI) has shown high accuracy in the diagnosis of AT [START_REF] Beranger-Gibert | Diagnostic value of MR imaging in the diagnosis of adnexal torsion[END_REF][START_REF] Ghossain | Adnexal torsion: magnetic resonance findings in the viable adnexa with emphasis on stromal ovarian appearance[END_REF]. Moreover, pelvic MRI may provide information regarding the actual nature of a pelvic mass [START_REF] Sadowski | Adnexal lesions: imaging strategies for ultrasound and MR imaging[END_REF]. In children, beyond the advantage of lack of ionizing radiation and excellent soft-tissue contrast provided by MRI, the diagnostic accuracy of MRI for suspected AT in children has not been reported.

The purpose of this study was to retrospectively assess the value of MRI for the diagnosis of AT in children and adolescents after inconclusive initial ultrasound examination.

Materials and methods

Population

We reviewed patients with suspected AT with an inconclusive ultrasound examination as a firstline imaging modality that required MRI as a second-line technique between 2010 and 2017.

Patients were further included when the final diagnosis was confirmed after surgery and/or clinical and imaging follow-up for at least 3 months. Patients with other diagnosis than AT were excluded as well as those who did not undergo ultrasound follow-up after the initial ultrasound.

Figure 1 shows patients inclusion/exclusion process into the study. All procedures were in accordance with the ethical standards of the local ethics committee on human experimentation.

Informed consent was not required due to the retrospective design of the study.

A total of 28 girls with a mean age of 12 ± 4 (standard deviation [SD]) years (range: 1 month -18 years) were evaluated for suspected AT with an initial inconclusive ultrasound examination followed by pelvic MRI. Demographic and clinical data of included patients were recorded.

Ultrasound examination

Initial ultrasound examination. Ultrasound was performed with Aplio ® 400 or 500 ultrasound devices (Toshiba Medical Systems Corporation) with a 5-to 8-MHz curved array and 7-to 12-MHz linear probes and included complete examination of the abdomen and pelvis. Endovaginal ultrasound was not performed in this pediatric population. Ultrasound was performed by pediatric radiologists with at least 6 years of experience with abdominal ultrasound or by residents under supervision by a certified pediatric radiologist.

Ultrasound follow-up. Patients who had no MRI findings consistent with AT and no surgery, underwent ultrasound follow-up. A second ultrasound examination was performed within the first week after the initial ultrasound, followed by a third ultrasound examination between 6 and 8 weeks after the initial ultrasound. Pain reduction associated with an ultrasound appearance of a collapsed hemorrhagic cyst confirmed the absence of AT. Moreover, when surgery was performed, the presence of an involution or a normal appearance of the ovary was recorded at ultrasound follow-up.

MRI examination

MRI protocol

MRI examination was performed with a 1.5-Tesla system (Achieva ® , Philips Medical Systems) with a phased-array pelvic coil for optimal signal-to-noise ratio. One patient underwent MRI examination under sedation and one with postprandial swaddling. MRI examinations were performed using various protocols, including at least the following sequences: sagittal and axial turbo spin echo T2-weighted sequences and axial gradient-echo T1-weighted sequences with and without fat signal suppression. Delayed contrast-enhanced axial and sagittal gradient-echo T1weighted sequences after intravenous administration of a gadolinium chelate (Gadoterate meglumine, Dotarem ® , Guerbet) were obtained for 21 patients (1 minute after intravenous injection of 0.02 mL/kg) Three patients underwent pelvic MR diffusion imaging. All MRI examinations were performed within a few hours after initial ultrasound examination.

MR image analysis

MR images were reviewed retrospectively on a picture-archiving workstation by two independent radiologists (E.B. and E.R.) with 15-and 4-years of experience in pediatric MRI, respectively, who were blinded to the surgical and pathological data. Each reader worked independently blinded to the results of the original interpretation and to the final diagnosis.

Readers were asked to provide the most plausible diagnosis. No patients were excluded due to poor MRI examination quality. MR images were analyzed qualitatively and quantitatively.

Qualitative data.

MR images of the ovary were evaluated for presence of ovarian stromal edema, peripheral distribution of follicles, asymmetric ovarian parenchymal enhancement and ovarian shift to the involved side. Regarding the adnexa, the following features were noted:

thickening or dilatation of the fallopian tube (comparatively with controlateral tube), presence of a whirlpool sign (twisted ovarian pedicle or fallopian tube), defect of enhancement of tubal wall on the pathological side, vascular pedicle enlargement (comparatively with controlateral), inflammatory pelvic fat, and uterine displacement. Moreover, the presence of an adnexal mass and its characteristics were noted: solid and/or cystic components with or without fat stranding or hemorrhagic content (e.g., hyperintensity on T1-weighted and T2-weighted images or presence of a fluid-fluid level in cyst with hemorrhagic content). Etiological hypotheses regarding the mass on MR images included functional follicular and paratubal cysts with or without hemorrhage and ovarian teratoma.

Quantitative data.

For each ovary, the following variables were retrospectively measured: ovary alone (ovary-corrected surface and volume), mass alone (axis/diameter, surface, volume), and ovary and mass together (total axis/diameter, total surface, total volume). For this, each radiologist performed measurements on axial MR images for ovarian dimensions and ovarian, axial and sagittal sections for ovarian volume measurements. The choice of sections was at the discretion of the radiologist who selected the images on which the ovarian dimensions were the largest. The ratios of the dimensions of the abnormal to the normal contralateral ovary were calculated.

After independent reading of which results were used to calculate interobserver agreement, discordant opinions were resolved by a consensus reading. The results of the consensus reading were used for further statistical analysis.

Standard of reference

Among the 28 patients, 10/28 (36%) had AT and 18/28 (64%) had no AT. In the 10 patients with AT, the diagnosis was confirmed by surgery as a standard of reference as follows:

intraoperative findings of an enlarged ovary associated with a torsion of the adnexal tube. The ovary was non-viable in 8 and oophorectomy was performed. Ovarian necrosis was confirmed by pathology in these 8 patients. Conservative treatment with detorsion was performed in 2 patients with AT. In the 18 patients without AT, the diagnosis was assessed using laparoscopy or follow-up. In 6 patients, laparoscopy was performed after MRI and found a luteal hemorrhagic cyst with an ovary and adnexa of normal aspect. In 12 patients, clinical and ultrasound follow-up confirmed the diagnosis of hemorrhagic cyst with typical signs of clot involution and visualization of a normal echo structure and size of the ovarian parenchyma.

A total of 22/28 (79%) patients had an ovarian or a tubal mass: for 17/28 (61%), these were cysts with hemorrhagic content (16 ovarian functional cysts and 1 paratubal cyst) and for 4/28 (14%), they were ovarian teratomas. One patient had a paratubal cyst without hemorrhagic content.

Statistical analysis

Quantitative variables were expressed as means ± standard deviation [SD], and ranges.

Qualitative data were expressed as raw numbers, proportions and percentages.

The diagnostic performance analysis of MRI was conducted based on the consensus results by considering the final diagnosis of AT. To identify factors associated with the diagnosis of AT on MRI, we compared patients with AT and those without AT. Categorical (qualitative) variables were compared using the chi-square or Fisher's exact tests. Continuous (quantitative) variables were compared using the Student t test or Mann-Whitney test after normality of the distribution has been checked using the Shapiro-Wilk test. The relationships between each MRI criteria and the diagnosis of AT was tested by univariate or exact univariate logistic regression analysis. The exact method was used when there was a complete separation of data.

Quantitative variables on MRI were dichotomized after optimal thresholds were determined by identifying the value with the maximal Youden's index and the shortest distance from the upperleft corner on receiver operating curve (ROC) analysis. Corresponding odds ratios (OR) along with their 95% confidence intervals (95% CI) and area under the ROC curve (AUC) were computed by unadjusted exact logistic regression to account for the relatively low sample size of the study and the occurrence of null percentages cells. Significance was set at P < 0.05.

For each categorical variable on MRI, sensitivity, specificity were estimated and the 95% exact CI were calculated.

The Kappa coefficients were computed along with their 95% CI to assess inter observer agreement (senior vs. junior radiologist) in terms of MRI findings. Degrees of agreement were categorized as follows: 0.00-0.

Results

Mean age was lower in patients with AT (9 ± 5 [SD] years; range: 4 months-15 years) than in those without AT (14 ± 1 [SD] years; range: 11-16 years) (P = 0.01). Table 1 shows the distribution of MRI findings in patients with AT and those without AT. The whirlpool sign (P < 0.001), tubal thickening (P = 0.0001), presence of ovarian T1-weighted hyperintensity (P = 0.032) (Figure 2) and vascular pedicle enlargement (P = 0.041) were more frequently observed in patients with AT than in those without AT (Table 1). AT was more frequent with a mature cystic teratoma versus no mass (P = 0.003). Among patients with hemorrhagic cysts, AT was found in 2/17 patients (12%) (Figure 3). The remaining categorical variables were not associated with AT (Figures 4 and5).

The results of quantitative analysis are presented in Table 2. When a mass was present on MRI, patients with AT had a larger mass, larger adnexal mass surface and larger adnexal mass volume than those without AT (Table 2).

Table 3 shows the results of univariate analysis with exact logistic regression to determine the most discriminative MRI variable to differentiate between patients with AT and those without

AT. An age < 13 years was associated with AT (OR: 10.7; 95% CI: 1.3 -148.2) (P = 0.022).

Regarding MRI features, univariate logistic regression analysis showed significant positive association between presence of a whirlpool sign and AT (OR: 61.0; median unbiased estimate, 7.2) (P < 0.0001). Tube thickening, absence of a cystic mass with hemorrhagic content, vascular pedicle enlargement and asymmetric ovarian enhancement were also associated with AT. In patients with adnexal mass, qualitative MRI features associated with AT were mass volume and abnormal ovary-corrected volume ≥ 30 cm 3 , axis length ≥ 5 cm, and surface area ≥ 14 cm 2 (Table 3).

The sensitivity, specificity and accuracy of each MRI variables for the diagnosis of AT are reported in

Discussion

The results of our study reveal that MRI had high degrees of accuracy, sensitivity and specificity for the diagnosis of AT in children after an inconclusive initial ultrasound examination. Also, agreement between two readers with 4 to 15 years of experience in MRI was perfect. Therefore, a strategy of ultrasound as the first step followed by MRI in patients with inconclusive ultrasound examination for the diagnosis of AT appears to be helpful.

Ultrasound is usually used for first-line imaging work-up in children with suspected AT in the emergency department. However, previous studies of the diagnosis of AT in children reported an overall sensitivity of ultrasound ranging from 51% [START_REF] Oltmann | Cannot exclude torsion: a 15-year review[END_REF] to 90.9% and low specificity (68.7%) [START_REF] Jourjon | Analysis of clinical and ultrasound determinants of adnexal torsion in children and adolescents[END_REF]. Ultrasound evaluation of ovaries might be more challenging in children than adults.

The ovaries in neonates can be small and may not be found in the pelvis but in a more cranial position [START_REF] Sintim-Damoa | Pediatric ovarian torsion: spectrum of imaging findings[END_REF] or in a herniated canal of Nuck [START_REF] Rees | Canal of Nuck hernia: a multimodality imaging review[END_REF]. Moreover, detailed evaluation of the ovaries has been described in adults by using a transvaginal approach that should not be performed in children and rarely in adolescents. Due to these limitations two main sources of inconclusive ultrasound examination in children and adolescents have been identified: hemorrhagic cysts and the presence of a large mass that stretches the ovarian parenchyma and precludes its precise evaluation [START_REF] Jourjon | Analysis of clinical and ultrasound determinants of adnexal torsion in children and adolescents[END_REF].

Consequently, to assess ovarian torsion in children, other methods should be used in cases of inconclusive initial ultrasound examination [START_REF] Riccabona | European Society of Paediatric Radiology abdominal imaging task force recommendations in paediatric uroradiology, part IX: Imaging in anorectal and cloacal malformation, imaging in childhood ovarian torsion, and efforts in standardising paediatric uroradiology terminology[END_REF]. Oltmann et al. reported that a strategy of diagnostic laparoscopy used as a first-line examination in children, particularly those with a pelvic mass ≥ 5 cm, may improve ovarian salvage as compared with ultrasound [START_REF] Oltmann | Cannot exclude torsion: a 15-year review[END_REF]. However, such a strategy may lead to a high rate of surgery in false-positive cases because clinical and laboratory findings are non-specific in AT. Moreover, surgery may cause adhesions in the pelvic cavity that may predispose to AT [START_REF] Chiou | Adnexal torsion: new clinical and imaging observations by sonography, computed tomography, and magnetic resonance imaging[END_REF]. As reported by Chiou et al. in a series of AT in adults, 48% of patients had a history of abdominal/pelvis surgery [START_REF] Chiou | Adnexal torsion: new clinical and imaging observations by sonography, computed tomography, and magnetic resonance imaging[END_REF].

CT may represent a second-line imaging modality for the diagnosis of AT because it is widely available in emergency settings. In a recent survey, CT has even been reported as a firstline examination modality for the diagnosis of AT in children or adolescents referred for pelvic pain in adult hospitals as compared with pediatric hospitals, where ultrasound is preferred [START_REF] Rialon | Diagnostic evaluation of ovarian torsion: an analysis of pediatric patients using the Nationwide Emergency Department Sample[END_REF].

Although AT findings have been described by CT in children in a few pictorial reviews [START_REF] Ngo | Pediatric ovarian torsion: a pictorial review[END_REF][START_REF] Chang | Pearls and pitfalls in diagnosis of ovarian torsion[END_REF] and in a study of 3 pre-menarchal girls [START_REF] Hiller | CT features of adnexal torsion[END_REF], the use of CT to primarily diagnose ovarian torsion is not supported by the literature. In adults and children, Chiou et al. demonstrated that although CT shows features suggestive of torsion, the diagnostic value of initial CT is less than that of initial ultrasound [START_REF] Chiou | Adnexal torsion: new clinical and imaging observations by sonography, computed tomography, and magnetic resonance imaging[END_REF]. In adults, Swenson et al. reported that the diagnostic performance of CT does not significantly differ from that of ultrasound in identifying ovarian torsion [START_REF] Swenson | Ovarian torsion: case-control study comparing the sensitivity and specificity of ultrasonography and computed tomography for diagnosis in the emergency department[END_REF].

Moreover, unlike ultrasound and MRI, CT exposes children to ionizing radiation and has lower contrast resolution as compared with MRI.

To date, the radiology literature describing MRI features for the diagnosis of AT in children consists mainly of single case reports [START_REF] Bader | Torsion of a normal adnexa in a premenarcheal girl: MRI findings[END_REF][START_REF] Cheng | Ovarian torsion: appearance on MRI[END_REF][START_REF] Van Kerkhove | Ovarian torsion in a premenarcheal girl: MRI findings[END_REF]. Two retrospective studies including a small number of children demonstrated the ability of MRI to detect AT: 6/58 patients aged 12 to 17 years in the study by Chiou et al. and 25 patients aged between 5-and 85 years (median 40 years) in the study by Rha et al. [START_REF] Chiou | Adnexal torsion: new clinical and imaging observations by sonography, computed tomography, and magnetic resonance imaging[END_REF][START_REF] Rha | CT and MR imaging features of adnexal torsion[END_REF]. However, neither was exclusive to the pediatric population.

In our series, the two main criteria associated with AT were an age under 13 years and a whirlpool sign. In pre-menarcheal girls, AT occurs more often without an ovarian or tubal mass [START_REF] Jourjon | Analysis of clinical and ultrasound determinants of adnexal torsion in children and adolescents[END_REF]. Similarly, a predictor of AT in our study and premenarchal girl was the absence of a cystic mass with hemorrhagic content. In our study, hemorrhagic functional cysts are exclusively seen in menarcheal girls and corresponded to the main differential diagnosis of AT. Moreover, presence of AT was associated with a large mass, with volume ≥ 30 cm 3 , axis length ≥ 5 cm and surface area ≥ 14 cm 2 . In our series, these large masses were represented essentially by mature cystic teratomas, as in other studies [START_REF] Ngo | Pediatric ovarian torsion: a pictorial review[END_REF][START_REF] Servaes | Sonographic findings of ovarian torsion in children[END_REF].

The presence of a whirlpool sign on MRI had the strongest association with AT, with substantial inter-reader agreement. In a recent study evaluating the value of MRI for the diagnosis of AT in adults with an equivocal adnexal mass seen on ultrasound, Beranger-Gilbert et al. found a whirlpool sign and thickened tube as MRI features associated with AT [START_REF] Beranger-Gibert | Diagnostic value of MR imaging in the diagnosis of adnexal torsion[END_REF].

Although the whirlpool sign, a direct representation of the twisted pedicle and tube, has been described on ultrasound in adults [START_REF] Valsky | Whirlpool sign in the diagnosis of adnexal torsion with atypical clinical presentation[END_REF], it is hardly identified in children on ultrasound [START_REF] Jourjon | Analysis of clinical and ultrasound determinants of adnexal torsion in children and adolescents[END_REF].

Therefore, MRI, showing more easily this sign, can be used as an accurate second-line imaging modality. Other MRI features associated with a diagnosis of AT on univariate analysis were tube thickening, vascular pedicle enlargement and asymmetric ovarian enhancement. For the last two features, the inter-reader agreement was poor to fair, which may indicate that identification of these two signs depends on the experience of the MRI reader and should prompt specific training among radiology residents.

The rate of oophorectomy was relatively high in our study as compared with most recent studies, with 50% oophorectomy performed for ovarian necrosis [START_REF] Rousseau | Emergency management and conservative surgery of ovarian torsion in children: a report of 40 cases[END_REF][START_REF] Santos | Outcome following detorsion of torsed adnexa in children[END_REF]. This result may account for the delay between the onset of symptoms and the initial ultrasound in this group of children and the delay between the initial ultrasound and pelvic MRI, although MRI was performed within a few hours after the initial ultrasound in our centre which has good availability of MRI. Recent recommendations specified that MRI should not be performed if it delays the potential surgery [START_REF] Riccabona | European Society of Paediatric Radiology abdominal imaging task force recommendations in paediatric uroradiology, part IX: Imaging in anorectal and cloacal malformation, imaging in childhood ovarian torsion, and efforts in standardising paediatric uroradiology terminology[END_REF]. Although the availability of MRI has increased in most pediatric centers in emergency settings, the need for sedation to avoid motion artifacts in young patients and the long examination time with MRI may lengthen a diagnostic algorithm including MRI as a second-line imaging modality.

Our study has some limitations. First, MR images were read by experienced pediatric radiologists. Therefore, our results cannot be generalized to most radiologists in daily practice who do not have similar experience. Second, we did not include patients with acute pelvic pain and negative ultrasound examination because we assumed that the ultrasound examination had ruled out AT. Therefore, the number of patients with false-negative findings might have been underestimated. Third, although this is the first exclusive pediatric study to specifically evaluate MRI features for the diagnosis of AT, the number of patients with AT was limited. Fourth, we did not compare ultrasound and MRI features associated with AT. Because the radiologists ended their initial ultrasound reports with "cannot rule out adnexal torsion", we considered that we could not retrospectively review ultrasound images and perform a head-to-head comparison of ultrasound and MRI data. Finally, in a context in which gadolinium-based contrast agents should be used judiciously in children, techniques such as diffusion MRI could represent an alternative to sequences with contrast media administration [START_REF] Kato | Diffusion-weighted imaging of ovarian torsion: usefulness of apparent diffusion coefficient (ADC) values for the detection of hemorrhagic infarction[END_REF][START_REF] Ozdemir | Contribution of diffusion-weighted imaging to conventional MRI for detection of haemorrhagic infarction in ovary torsion[END_REF][START_REF] Rozenfeld | Gadolinium-based contrast agents in children[END_REF][START_REF] Samanci | Apparent diffusion coefficient measurement of ovarian stroma: a potential tool for the diagnosis of polycystic ovary syndrome[END_REF]. Only three children underwent pelvic diffusion sequences in our series. Therefore, we could not compare the two techniques.

In conclusion, in children with suspected AT and an inconclusive initial ultrasound examination, MRI as a second-line imaging modality has high sensitivity and accuracy for the diagnosis of AT. We found that tubal thickening and whirlpool signs are potential MRI signs to improve sensitivity in patients with equivocal ultrasound findings. However, such a strategy should not delay potential surgery.

FIGURE/TABLE LEGENDS

Figure 1 :

 1 Figure 1: Flow chart shows the patients inclusion/exclusion process into the study. AT = adnexal torsion; MRI = magnetic resonance imaging; US = ultrasound.

Figure 2 :

 2 Figure 2: Adnexal torsion in a 13-year-old girl with a benign cystic mature teratoma. On ultrasonography (not shown), the right ovary could not be identified. a, T2-weighted MR image in sagittal plane shows an enlarged right ovary (black arrow), with parenchymal hyperintensity, peripheral distribution of follicles (arrowheads) and a whirlpool sign (white arrow). A mass with a cystic and solid component is identified. b, c, The presence of hyperintense fat signal (arrows) on axial T1-weighted sequences without (b) and with fat signal suppression (c) suggests ovarian teratoma. d, No enhancement of right ovary is observed after intravenous administration of a gadolinium chelate (d).

Figure 3 :

 3 Figure 3: Left adnexal torsion in a 14-year-old menarcheal girl with a hemorrhagic cyst. a, Abdominal ultrasound image shows an enlarged left ovary (arrow) with a central hemorrhagic cyst (arrowheads). b, T2-weighted MR image in the axial plane confirms left ovary enlargement with a central cyst (arrow) and shows peripheral distribution of follicles (arrowheads) as well as global mild hyperintensity of the ovarian parenchyma and hyperintensity of the hemorrhagic cyst. c, T1-weighted MR image in the axial plane shows slightly hyperintense ovarian parenchyma (arrow). d, Substracted T1-weighted MR image in the axial plane obtained after intravenous administration of a gadolinium chelate shows no enhancement of ovarian parenchyma (arrow). Surgery confirmed the left ovary ischemia

Figure 4 :Figure 5 :

 45 Figure 4: Hemorrhagic cyst in a 16-year-old girl. a, Abdominal ultrasound image shows enlarged ovary (arrows) with a central hemorrhagic cyst (arrowheads). The presence of an adnexal torsion on a hemorrhagic cyst could not be ruled out with ultrasound. b, c, MRI confirms the presence of hemorrhagic cyst (arrowheads on b and c). The parenchyma of the left ovary has a normal appearance on axial T2-weighted image (b) with a moderate stromal hyperintensity. On T1-weighted MR image in the sagittal plane (c), the ovarian parenchyma has a normal appearance and hemorrhagic cyst harbors fluid-fluid level (arrowheads). Moderate free peritoneal fluid is present (b, c and d). d, Fat suppressed T1-weighted MR image in the axial plane obtained intravenous administration of a gadolinium chelate shows normal enhancement of left ovary parenchyma (arrows) excluding ovarian torsion

Table 4 .

 4 The single patient falsely positive for AT had a hemorrhagic cyst seen at laparoscopy. The overall accuracy of MRI for the diagnosis of AT was 96% (27/28; 95% CI: 82

-100%) and sensitivity 100% (10/10; 95% CI: 69 -100), specificity 94% (17/18; 95% CI: 73 -100), with perfect interobserver agreement (κ =1 [95%CI: 1.00 -1.00]) (Table

5

). The most accurate variables for the diagnosis of AT were the presence of a whirlpool sign and a corrected volume of the abnormal ovary ≥ 30 cm 3 , with substantial interobserver agreement (κ =0.62 [95% CI: 0.29 -0.95] and κ = 0.61 [95% CI: 0.14 -1.00], respectively).

Table 1 .

 1 Comparison of MRI findings for categorical variables between 18 children with no adnexal torsion and 10 children with adnexal torsion.

Table 2 .

 2 Comparison of MRI findings for quantitative variables between 18 children with no adnexal torsion and 10 children with adnexal torsion.

Table 3 .

 3 Comparison of independent categorical criteria between patients with adnexal torsion and patients without adnexal torsion: results from exact logistic regression model.

Table 4 .

 4 Sensitivity, specificity and accuracy of MRI criteria for the diagnosis of adnexal torsion.

Table 5 .

 5 Interobserver agreement for MRI features using an analytical method in the case of dichotomous variables.

	Ovary-corrected surface area (cm 2 )
	Abnormal surface area (n = 20)	4.12 ± 1.85 [0.01 -7.10]	9.88 ± 9.73 [2.00 -22.0]	0.705
	Ratio (abnormal to normal) (n=20)	0.95 ± 0.96 [0.42 -4.33]	0.51 ± 0.52 [0.11 -1.25]	0.109
	Ovary-corrected volume (cm 3 )
	Abnormal volume (n = 20)	14.2 ± 9.0 [0.01 -38.0]	51.0 ± 34.0 [10.0 -91.0]	0.047
	Ratio (abnormal to normal) (n = 20)	0.35 ± 0.24 [0.13 -0.95]	0.11 ± 0.10 [0.01 -0.22]	0.021
	Bold indicates signifiant P value
	Variables are expressed as means ± standard deviations; numbers in brackets are ranges

AUC: area under the receiver operating characteristics curve. Bold odds ratios are statistically significant at P<0.05 Unadjusted odds ratios (95% confidence interval) from exact logistic regression modeling. *For cells with null percentages (i.e. ovarian T1 hyperintensity, whirlpool sign), median unbiased estimates are provided.

Conflict of interest

The authors report no conflict of interest Variables are expressed as raw numbers; numbers in parentheses are proportions followed by percentages. Bold indicates significance *For some variables, criteria were not assessable so that the denominator is different from 18 or 10.

No torsion Torsion P-value

Ovary

Ovarian T2 hyperintensity* 10 (10/17; 59%) 5 ( * Quantitative variables were dichotomized after optimal thresholds were determined by identifying the value with the maximal Youden's index and the shortest distance from the upper-left corner on ROC analysis. Sensitivity, specificity and accuracy are expressed as percentages; numbers in parentheses are proportions; followed by 95% confidence intervals into brackets.


Jacques Lerman

Christophe Hennequin

Isabelle Etienney

Laurent Abramowitz

Gael Goujon

Jean-Marc Gornet

Sophie Guillerm

Thomas Aparicio

Alain Valverde

Pierre Cattan

MD Laurent Quéro
email: laurent.quero@aphp.fr

Impact of tobacco smoking on the patient's outcome after (chemo)radiotherapy for anal cancer

Keywords: anal, cancer, radiotherapy, chemoradiotherapy, tobacco, prognosis

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Anal cancer is a rare disease with 8,580 new cases per year estimated in the United States and 4,300 cases in Europe. It is accounting for 1%-2% of all gastrointestinal cancers and 2%-4% of colon, rectal and anal tumors [START_REF] Glynne-Jones | Anal cancer: ESMO-ESSO-ESTRO Clinical Practice Guidelines for diagnosis, treatment and follow-up[END_REF]. Despite the rarity of anal cancer, the incidence has almost doubled in recent years, from 1.2 cases per 100,000 per year during 1973-1996 to 2.2-2.5 cases per 100,000 per year during 1997-2013 [START_REF] Nelson | Changing patterns of anal canal carcinoma in the United States[END_REF][START_REF] Abramowitz | Epidemiological and economic burden of potentially HPV-related cancers in France[END_REF].

Approximately 85% of anal cancer are squamous cell carcinoma and are mainly associated with human papillomavirus (HPV) infection, particularly serotypes 16 and 18 [START_REF] Abramowitz | Human papillomavirus genotype distribution in anal cancer in France: the EDiTH V study[END_REF]. Anal cancer incidence increases with age and is higher in women than men. High-risk populations for anal cancer also include human immunodeficiency virus (HIV)-positive patients, men who have sex with men, patients who are current or former cigarette smokers, women with a history of preinvasive or invasive cervical or vulvar lesions and organ transplant recipients [START_REF] Van Der Zee | The increasing incidence of anal cancer: can it be explained by trends in risk groups?[END_REF].

Localized small cancers (T1N0) are mainly treated by exclusive radiation therapy in the case of cancers of the anal canal, or by surgery in the case of cancers of the anal margin. The recommended treatment of locally advanced tumours (T2-T4, N0-N2) is definitive concomitant radio-chemotherapy [START_REF] Moureau-Zabotto | Anal cancer: French Intergroup Clinical Practice Guidelines for diagnosis, treatment and follow-up (SNFGE, FFCD, GERCOR, UNICANCER, SFCD, SFED, SFRO, SNFCP)[END_REF].

Several studies reported that tobacco smoking was a risk factor for anal cancer [START_REF] Daling | Sexual practices, sexually transmitted diseases, and the incidence of anal cancer[END_REF][START_REF] Moura | The magnitude of the association between smoking and the risk of developing cancer in Brazil: a multicenter study[END_REF][START_REF] Holmes | Anal cancer in women[END_REF]. Odds ratios for anal cancer among smokers versus non-smokers was between 2-4 in women and 4-5 in men [START_REF] Daling | Sexual practices, sexually transmitted diseases, and the incidence of anal cancer[END_REF][START_REF] Coffey | Lifestyle and reproductive risk factors associated with anal cancer in women aged over 50 years[END_REF][START_REF] Daling | Cigarette smoking and the risk of anogenital cancer[END_REF][START_REF] Frisch | Tobacco smoking as a risk factor in anal carcinoma: an antiestrogenic mechanism?[END_REF]. Some studies reported a correlation between pack-years of smoking and anal cancer (RR=1.9 for 20 pack years and RR=5.2 for 50 pack-years, p value <0.001) [START_REF] Frisch | Tobacco smoking as a risk factor in anal carcinoma: an antiestrogenic mechanism?[END_REF][START_REF] Holly | Anal cancer incidence: genital warts, anal fissure or fistula, hemorrhoids, and smoking[END_REF][START_REF] Rabkin | Second primary cancers following anal and cervical carcinoma: evidence of shared etiologic factors[END_REF]. Constituents of tobacco may act directly as carcinogens or indirectly through suppression of the immune response to HPV.

It has been reported that tobacco was associated with higher tumor relapse or lower progression free survival in cervical and bladder cancers [START_REF] Hou | Association of smoking status with prognosis in bladder cancer: A meta-analysis[END_REF][START_REF] Waggoner | Association between cigarette smoking and prognosis in locally advanced cervical carcinoma treated with chemoradiation: a Gynecologic Oncology Group study[END_REF].

The primary aim of our study was to evaluate progression-free survival according to tobacco status.

The other aims were to evaluate overall survival, disease-free survival, colostomy-free survival and identify others prognostic factors associated with progression-free survival.

Methods

We retrospectively identified from our medical database, 171 patients treated with radiotherapy or chemo-radiotherapy in our institution between 2000 to 2015 for non-metastatic anal cancer. To be included, patients had to have biopsy proven squamous cell anal carcinoma and non-metastatic anal carcinoma at the initial staging with 18-FDG-PET-CT (Positron emission tomography and computed tomography) or thoracic, abdominal, and pelvic CT, pelvic MRI (magnetic resonance imaging) or anal endoanal ultrasound.

Patients were staged according to the 7 th edition of the AJCC Cancer Staging Manual for anal cancer.

In our study, we analysed factors potentially correlated with poor overall survival. Following factors were analysed: age, performance status, gender, tumor size, tumor location (anal verge, anal canal, rectal extension), lymph node involvement, tumor differentiation, HIV status, initial tumor resection, condyloma, induction chemotherapy, radiotherapy duration, smoking habits (current smoker was defined as a patient who smoked greater than 100 cigarettes in his lifetime and has smoked at the time of the anal cancer diagnostic, former smoker as a patient who has smoked greater than 100 cigarettes in his lifetime and was smoke free for 3 years at the time of anal cancer diagnostic and non-smoker as a patient who has not smoked greater than 100 cigarettes in his lifetime and did not smoke at the time of the anal cancer diagnostic).

Radiotherapy

Patients received initial irradiation to the anal canal and pelvic lymph nodes (45 Gy) followed by a boost delivered in the anal tumor and all pathological lymph nodes [START_REF] Rabkin | Second primary cancers following anal and cervical carcinoma: evidence of shared etiologic factors[END_REF], in daily fractions of 1.8 Gy, 5 days per week, by high energy photon beams (≥6 MV). Most of the patients were treated with a 3D technique.

Chemotherapy

Patients with locally advanced anal tumor (tumor size ≥3cm or lymph nodes involvement) received concurrent chemotherapy by 5-fluorouracil(1000 mg/m²/d, days 1-4, days 28-31 +/-days 56-59) or capecitabine (1600 mg/m²/day, 5 days per week during all the radiotherapy treatment) and mitomycin C (12 mg/m²/day, day 1, day 28 +/-day 56). Patients with locally advanced disease could receive induction chemotherapy by 5-fluorouracil, docetaxel and cisplatin (DCF) [START_REF] Kim | DCF (docetaxel, cisplatin and 5-fluorouracil) chemotherapy is a promising treatment for recurrent advanced squamous cell anal carcinoma[END_REF].

Follow-up

Patients were followed-up at 4-month intervals for the first year, at 6-month intervals for the next 2 years and annually thereafter. The follow-up evaluation consisted of physical examination, a complete blood count, liver function test and a SCC marker. All patients had MRI at 6-month intervals for the first 2 years and annually thereafter.

Statistical analysis

Progression-free survival (PFS) was measured from the date of the first day of treatment to the date of first disease progression or death from any cause. Patients who were alive without recurrence were censored at the date of last follow-up. Locoregional-relapse-free survival (LRFS) was measured from the date of the first day of treatment to the date of locoregional disease progression or death from any cause. Local recurrence was defined as recurrence within the pelvis and regional recurrence included a pelvic or inguinal lymph node recurrence. Patients who were alive without locoregional recurrence were censored at the date of last follow-up. Colostomy-free survival (CFS) was the time period measured from the date of the first day of treatment to the colostomy or death from any cause without colostomy. Patients who were alive without colostomy were censored at the date of last follow-up. Overall survival (OS) was measured from the date of the first day of treatment to the date of death from any cause. Patients who were alive were censored at the date of last follow-up.

Survival curves were calculated by using Kaplan-Meier survival analysis. The log-rank test was used to evaluate survival differences. Comparison of continuous variables was performed using the student t-test. Cox regression analysis was used to perform a multivariate analysis, incorporating T and N stages, histology, surgery. Statistical analyses were performed using Stata 14.2 software (College Station, TX: StataCorp LP). Statistical significance was set at p<0.05.

Results

The mean age of our study population at the time of diagnosis was 62 years [Range: 36-89]. Most of the patients were women (74%). Eighty-six patients (50%) had T1-T2 and N0 tumor and eighty-five (50%) had T3-T4 and/or N+ tumor. Twenty-one patients (12%) were HIV-positive at the time of diagnosis. Data about smoking status at the time of the diagnosis was available in 163/171 patients: 58 current smokers, 28 former-smokers, and 77 non-smokers. Twenty-one patients (12%) had a positive history of anal warts. The mean follow-up period was 4.27 years (range: 0.15-14.5). These data are summarized in table 1. Analysis of p16 expression was not systematically performed. Only very few patients had their HPV/p16 status known.

One hundred and forty-six patients (85%) received concurrent chemo-radiotherapy and 25 patients (15%) received exclusive radiotherapy. Among patients treated by chemoradiotherapy, 104 (70 %) received 5FU-Mitomycin chemotherapy, 37 (25%) received 5FU-cisplatin chemotherapy and 5 (3%) received fluoropyrimidine monotherapy chemotherapy (5-fluorouracile/capecitabine). Thirty-two patients (19%) received induction chemotherapy and 7 (5%) adjuvant chemotherapy. Radiotherapy delivered a median total dose of 64.4 Gy and a mean total dose of 64.8 Gy (range 54-76.6). The distribution of the dose was very homogeneous: 90 percent of patient received a total dose between 60 and 65 Gy. One hundred and twenty-one patients among 171 received 64.8 Gy. Fifteen patients (9%) received a boost delivered by interstitial brachytherapy.

After a median follow-up of 48,7 months [7.5-176.2], 30 patients have died and 35 patients have relapsed.

Lung progression was a rare event in our study. Indeed, only 5 patients developed pulmonary metastases (2 smoker patients, 1 non-smoker patient and 2 patients whose smoking status was not available).

Three-and 5-year overall survival was 83.6% and 81% respectively. Three-and 5-year progressionfree survival was 79.2% and 78.1% respectively. Local-tumor control at 3 and 5 years was 83.2% and 82.1% respectively. Three-and 5-year colostomy-free survival was 87% and 83.7% respectively. Among 31 patients who had a colostomy, 6 patients had a colostomy before the start of the treatment for bowel obstruction or faecal incontinence and 25 had a colostomy after radiotherapy: 18 patients for local relapse and 7 patients for faecal incontinence.

Twenty-two patients had an initial tumor resection. The mean tumor size was 3.25 cm [START_REF] Glynne-Jones | Anal cancer: ESMO-ESSO-ESTRO Clinical Practice Guidelines for diagnosis, treatment and follow-up[END_REF][START_REF] Nelson | Changing patterns of anal canal carcinoma in the United States[END_REF][START_REF] Abramowitz | Epidemiological and economic burden of potentially HPV-related cancers in France[END_REF][START_REF] Abramowitz | Human papillomavirus genotype distribution in anal cancer in France: the EDiTH V study[END_REF][START_REF] Van Der Zee | The increasing incidence of anal cancer: can it be explained by trends in risk groups?[END_REF][START_REF] Moureau-Zabotto | Anal cancer: French Intergroup Clinical Practice Guidelines for diagnosis, treatment and follow-up (SNFGE, FFCD, GERCOR, UNICANCER, SFCD, SFED, SFRO, SNFCP)[END_REF] in this population vs 4.48 cm [START_REF] Glynne-Jones | Anal cancer: ESMO-ESSO-ESTRO Clinical Practice Guidelines for diagnosis, treatment and follow-up[END_REF][START_REF] Nelson | Changing patterns of anal canal carcinoma in the United States[END_REF][START_REF] Abramowitz | Epidemiological and economic burden of potentially HPV-related cancers in France[END_REF][START_REF] Abramowitz | Human papillomavirus genotype distribution in anal cancer in France: the EDiTH V study[END_REF][START_REF] Van Der Zee | The increasing incidence of anal cancer: can it be explained by trends in risk groups?[END_REF][START_REF] Moureau-Zabotto | Anal cancer: French Intergroup Clinical Practice Guidelines for diagnosis, treatment and follow-up (SNFGE, FFCD, GERCOR, UNICANCER, SFCD, SFED, SFRO, SNFCP)[END_REF][START_REF] Daling | Sexual practices, sexually transmitted diseases, and the incidence of anal cancer[END_REF][START_REF] Moura | The magnitude of the association between smoking and the risk of developing cancer in Brazil: a multicenter study[END_REF][START_REF] Holmes | Anal cancer in women[END_REF][START_REF] Coffey | Lifestyle and reproductive risk factors associated with anal cancer in women aged over 50 years[END_REF][START_REF] Daling | Cigarette smoking and the risk of anogenital cancer[END_REF][START_REF] Frisch | Tobacco smoking as a risk factor in anal carcinoma: an antiestrogenic mechanism?[END_REF][START_REF] Holly | Anal cancer incidence: genital warts, anal fissure or fistula, hemorrhoids, and smoking[END_REF][START_REF] Rabkin | Second primary cancers following anal and cervical carcinoma: evidence of shared etiologic factors[END_REF][START_REF] Hou | Association of smoking status with prognosis in bladder cancer: A meta-analysis[END_REF][START_REF] Waggoner | Association between cigarette smoking and prognosis in locally advanced cervical carcinoma treated with chemoradiation: a Gynecologic Oncology Group study[END_REF][START_REF] Kim | DCF (docetaxel, cisplatin and 5-fluorouracil) chemotherapy is a promising treatment for recurrent advanced squamous cell anal carcinoma[END_REF][START_REF] Al-Naeeb | Smoking and the risk of anal cancer recurrence: The Addenbrookes Hospital experience[END_REF] in the whole population of the study.

Five-year CFS and OS was 93.3% and 90.7% for non-smokers vs 79% and 81% for smokers (p=0.02 and p=0.03 respectively) (Figure 3, Figure 4). Prognostic factors associated with progression-free survival Univariate analysis results have been summarized in table 2. Prognostic factor correlated to poor progression-free survival (PFS) were tumor size >4cm, lymph node involvement; tobacco smoking, no initial surgical excision and anal warts at diagnosis. A tumor greater than 4 cm was significantly associated with a lower PFS. Five-year PFS was 85.5% for patients with a tumor less than or equal to 4 cm vs 69.2% for patients with a tumor greater than 4 cm (p=0.01).

The lymph node involvement was also associated with a lower PFS (p=0.03). 5-year PFS was 84.8% for patients staged N0, 71.1% for patients staged N1-N2 and 57.3% for patients staged N3.

Tobacco smoking status of patients was significantly associated with lower PFS. Five-year PFS was 88.1% for non-smokers vs 74.8% for current or former smokers (p=0.016) (Figure 1). More specifically, among smoker patients, former smokers had a better PFS than current smokers.

Five-year PFS was 88.1% for non-smokers vs 76.7% for former smokers vs 73.8% for current smokers (p=0.032) (Figure 2). Initial tumor resection was also independently associated with a better PFS. Five-year PFS was 95.2% for patients who had an initial tumor resection vs 75.6% who had not (p=0.049).

Gender, HIV status, tumor location, tumor grade, histological subtype, anogenital warts, baseline SCC antigen level, median total dose, induction chemotherapy, protocol of concurrent chemotherapy did not significantly correlate with PFS.

On multivariate analysis only tobacco smoking status remained significantly correlated to PFS (HR: 2.85; 95% CI: 1.25-6.50) (

Toxicity

Forty-six patients had G3+ acute skin toxicity (26.9%), 9 patients had G3+ acute gastrointestinal toxicity (5.26%) and 2 patients had G3 acute urinary toxicity (1.16%). Among patients who had severe acute toxicity (G3+), 20 patients were non-smokers and 26 were smokers.

There was no statistical correlation between severe acute toxicity (G3+) and tobacco smoking status (p=0.784).

We did not find any correlation between severe acute toxicity (G3+) and locoregional-disease-free progression, disease-free progression and colostomy-free survival (p=0.761; p=0.801 and p=0.116 respectively).

Discussion

In this large monocentric study, we have found that cigarette smoking was the strongest prognostic factor correlated with PFS for patients treated by RT+/-CT for anal cancer. Moreover, we have also observed a worse cancer treatment outcome between current and former smoker patients.

Some others studies have reported worse outcome in smoker patients after anal cancer treatment.

Bowzyk Al-Naeeb et al. have reported in a monocentric retrospective study of 105 patients treated by chemoradiotherapy at Cambridge hospital in UK that cigarette smoking increased the risk of recurrence with an Odds-Ratio of 17.4 (p=0.008) [START_REF] Al-Naeeb | Smoking and the risk of anal cancer recurrence: The Addenbrookes Hospital experience[END_REF]. A retrospective review of 64 cases of anal carcinoma from San Diego in California reported that current smokers had higher carcinoma recurrence rates than non-smokers (32% vs 20%). Smokers patients also died more frequently from recurrence than non-smokers patients with 45% of smokers dead compared to only 20% of nonsmokers by 5 years after treatment [START_REF] Ramamoorthy | Tobacco smoking and risk of recurrence for squamous cell cancer of the anus[END_REF]. A retrospective study of 63 patients treated for anal carcinoma mainly by chemoradiotherapy at Washington University Hospital reported a significant worse overall survival in ever-smokers than in never-smokers: 2-years overall survival was 75.4% vs 87.1% (p<0.05) [START_REF] Linam | Evaluation of the impact of HIV serostatus, tobacco smoking and CD4 counts on epidermoid anal cancer survival[END_REF]. In a retrospective study of 68 patients treated by chemoradiotherapy for anal carcinoma at the University of Heidelberg in Germany, Mai et al. find a statistically significant difference in local control between smokers and non-smokers (74% vs 94%, p = 0.03) but not in disease-specific survival and colostomy free survival (p=0.19 and p=0.15 respectively) [START_REF] Mai | The influence of smoking and other risk factors on the outcome after radiochemotherapy for anal cancer[END_REF].

Tobacco smoking is a significant risk factor for anal cancer as well as has a significant impact on anal cancer disease control and survival. This factor overcame all prognosis factors after multivariate analysis.

Past and current smoker status is not easy to determine and lack of difference observed between past and current smokers in our study should be analyzed with caution. Indeed, data regarding smoking habits are usually based on self-reports and not on biochemical tests for validation of information. It appears that self-reports regarding smoking habits have been found to be accurate in most studies. However, when taking into consideration subgroups of patients with smoking-related diseases, self-reports are less reliable. One of the main reasons for this contradiction might be that smokers feel under strong pressure to discontinue smoking, whilst at the same time they are unable to achieve this goal [START_REF] Attebring | Are patients truthful about their smoking habits? A validation of self-report about smoking cessation with biochemical markers of smoking activity amongst patients with ischaemic heart disease[END_REF].

How does tobacco smoking may contribute to cancer recurrence and worse outcome after (chemo)radiotherapy?

Diminished immune function and impaired tissue oxygenation may be involved at least in part.

It has been observed that chronic inhalation of cigarette smoke alters a wide range of immunological functions, including innate and adaptive immune responses [START_REF] Sopori | Effects of cigarette smoke on the immune system[END_REF]. In a review of literature, Norum et al. reported that tobacco smoking patients with non-small-cell lung carcinoma generally had a higher PD-L1 tumour proportion score and probably a higher mutational burden due to smoking, they also experienced a better overall response rate of immunotherapy than non-smokers [START_REF] Norum | Tobacco smoking and cessation and PD-L1 inhibitors in non-small cell lung cancer (NSCLC): a review of the literature[END_REF].

Cigarette smoking is also known to induce hypoxia, which may impact the oxygen-dependant effects of chemoradiation and may affect chemotherapy drugs delivery to tumor cells [START_REF] Jensen | Cigarette smoking decreases tissue oxygen[END_REF][START_REF] Harrison | Impact of tumor hypoxia and anemia on radiation therapy outcomes[END_REF].

As reported by others authors, we did not find a worse outcome among HIV-infected patients treated for anal cancer in our study [START_REF] Bryant | Association of HIV Status With Outcomes of Anal Squamous Cell Carcinoma in the Era of Highly Active Antiretroviral Therapy[END_REF].

A detailed smoking history should be part of future clinical evaluations in anal carcinoma. At least three levels of smoking status should be ascertained (never smoker, former smoker and current smoker). Our data and the literature showed patients must be encouraged to stop smoking once a diagnosis of anal carcinoma is made. Indeed, smoking status at the time of the diagnosis overcame all prognostic factors. A prospective study to determine if smoking cessation during treatment alters cancer outcomes could be meaningful. Immune checkpoint therapy in combination with chemoradiotherapy may be an interesting treatment approach in smoker patients with locally advanced anal cancer. Tumor mutational burden should be evaluated in anal cancer to predict

Progression-free survival according to smoking status

Figure 2

Progression-free survival according to three levels of smoking status

Figure 3

Colostomy-free survival according to smoker status

Figure 4

Overall survival according to smoker status

Figure 1

Progression-free survival according to smoking status

Figure 2

Progression-free survival according to three levels of smoking status

Figure 3

Colostomy-free survival according to smoker status

Figure 4 Overall survival according to smoker status 1 Figure 5

 415 Figure 4Overall survival according to smoker status

Table 2

 2 ).

	Prognostic factors associated with colostomy free survival (supplementary data)
	After univariate analysis, tumor stage, weight lost, tabaco smoking and boost by brachytherapy were
	statistically associated with overall survival.
	After multivariate analysis, weight lost and tabaco smoking remained statistically significant
	(p=0.003 and p=0.017 respectively).
	Prognostic	factors	associated	with	overall	survival	(supplementary	data)
	After univariate analysis, tumor stage, age ≥65, tumor length ≥4 cm, tabaco smoking were
	statistically associated with overall survival.
	After multivariate analysis, only tabaco smoking remained statistically significant (p=0.05)
	Induction chemotherapy had no detrimental effects on patients' outcome. 5-year disease-free
	survival rate was 84.8% vs 71.4% (p=0.11), 5-year colostomy free survival rate was 87.1% vs 71.3
	(p=0.11) and 5-year overall survival rate was 82.8% vs 78.0% (p=0.25) for non-smokers and smokers
	patients respectively.
	Treatments performed after disease progression
	Among patients who experienced a disease progression, 13 patients received chemotherapy (8
	smoker patients, 4 non-smoker patients, 1 patient whose smoker status was unavailable), 17
	patients had a salvage abdominoperineal resection (APR) (6 smoker patients, 11 non-smoker

After multivariate analysis, only tabaco smoking remained statistically significant (p=0.03).

Prognostic factors associated with locoregional-relapse free survival (supplementary data)

After univariate analysis, tumor length ≥4 cm and tabaco smoking were statistically associated with locoregional-relapse free survival.

3 patients had salvage abdominoperineal resection with inguinal lymph node dissection, 4 patients had inguinal or internal iliac lymph node dissection, 1 patient had a lobectomy and 1 patient had a hepatic metastasectomy.

Table 1

 1 Patient characteristics

	Number of	percentage
	patients

Table 2

 2 Univariate analysis of prognostic factors for progression-free survival (PFS) HIV= Human Immunodeficiency Virus; Squamous Cell Carcinoma; PFS= Progression-Free Survival; PET-CT= positron emission tomographycomputed tomography

	Patients (n)	5-year PFS (%)	p

Table 3

 3 Multivariate analysis of prognostic factors for progression-free survival (PFS)

		HR	Z	P>|z|	IC95%
	Tobacco status	2.85	2.49	0.013	[1.25-6.50]
	Tumor size >4cm 1.60	1.14	0.25	[0.71-3.57]
	N stage	1.44	1.34	0.18	[0.84-2.46]
	Surgical resection 0.30	-1.14	0.25	[0.039-2.34]

immune checkpoint blockade efficacy as it has become a useful biomarker in some cancer types for identification of patients that will benefit from immunotherapy.

Conclusions

Tobacco smoking at the time of anal cancer diagnosis is associated with increased risk for cancer recurrence, colostomy and death when compared with non-smokers. Future trials should be specifically designed for patients with HPV-negative and HPV-positive disease in smokers and nonsmokers according to different TNM staging. Regarding the worse disease outcome after treatment, immune checkpoint therapy in combination with chemoradiotherapy may be an interesting treatment approach in smoker patients with locally advanced anal cancer.

Conflict of interest declarations

The authors declare that they have no conflict of interest regarding the present article


Jérémy Picard

MD Gwenael Cornec

MD Raoul Baron

MD Philippe Saliou
email: philippe.saliou@chu-brest.fr

workers during COVID-19 lockdown: what did the public observe through the French media?

Keywords: COVID-19 pandemic, surgical mask, filtering face piece (FFP) mask, media

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

To deal with the Covid-19 pandemic, the systematic wearing of masks has gradually become widespread among all healthcare workers [START_REF] Lepelletier | What face mask for what use in the context of COVID-19 pandemic? The French guidelines[END_REF]. Indeed, the SARS-Cov-2 virus is now considered as mainly transmitted by droplets and masks are an effective barrier to fight the virus spreading [START_REF]Infection prevention and control and preparedness for COVID-19 in healthcare settings -third update[END_REF]. This information was quickly relayed by the media and the demand for masks skyrocketed in patients and general population [START_REF] Cheng | Wearing face masks in the community during the COVID-19 pandemic: altruism and solidarity[END_REF][START_REF] Cheng | The role of community-wide wearing of face mask for control of coronavirus disease 2019 (COVID-19) epidemic due to SARS-CoV-2[END_REF]. Even if the usefulness of wearing a mask among the general population has come to be widely accepted, the French government has long opposed its systematic use. In normal times, professionals may already be confused by the variety of masks and its indications. In addition, many institutions are facing a shortage that forces learned societies to review the indications and methods of use [START_REF] Kampf | COVID-19-associated shortage of alcohol-based hand rubs, face masks, medical gloves and gowns -proposal for a risk-adapted approach to ensure patient and healthcare worker safety[END_REF]. Operational hygiene teams are used to train healthcare workers in the proper use of masks. These training courses are unfortunately infrequent in normal times and only concern healthcare professionals [START_REF] Uguen | Influence of risk assessment inspection on the prevention of nosocomial infection[END_REF].

The general public is constantly exposed to images of masking through the various media [START_REF] Leung | Mass masking in the COVID-19 epidemic: people need guidance[END_REF]. Their behaviour may be induced by this exposition. This is also the case for caregivers who are exposed to these representations daily. However, the pictures disseminated do not always comply with good practice.

The aim of this study is to assess the wearing of masks appropriateness observed in the images broadcast by the main French media during this lockdown period.

Methods

We conducted a prospective study from March 30, 2020 to May 11, 2020, during the public lockdown period decided by the French government following the spread of confirmed Covid-19 cases and Intensive Care Units saturation.

We reviewed some of the main French information media websites: Le Monde, Le Figaro, Libération, L'Obs, Le Point, L'Express, BFM TV and CNews, and one regional newspaper website: Le Télégramme. We daily collected photographs presented on the home page, or on the dedicated Covid-19 page, where a face mask worn by a French healthcare worker could be seen. We then evaluated its compliance with good practices.

Le Monde is a generalist daily national journal with about 323,000 subscribers in 2020, whose website received more than 210 million visits in April 2020. Le Figaro is a daily journal with 326,000 subscribers and a website consulted more than 210 million times in April 2020.

Le Point and L'Express are weekly magazines respectively distributed to 290 million people and 201 million people, and their websites have been consulted respectively 53 million times and 39 million times in April 2020. BFMTV and CNews are the main continuous 24/7 news channels accessible from every TV posts, and BFMTV website have been consulted 180 million times. Finally, Le Telegramme is the local journal distributed at Brest Hospital, it's delivered to more than 180,000 people every day and its website received 18 million visits in April 2020 [START_REF]Fréquentation internet[END_REF].

In France, there are commonly two types of face masks for medical use. The first one is the anti-projection mask or surgical mask and the second one is a respiratory protection device or filtering face piece, usually class 2 (FFP2), the latter being equivalent to an N95 facemask. Surgical mask wearing is recommended for healthcare workers in contact with a person presenting signs of respiratory infection, and in the absence of invasive procedures on the respiratory tract. On the contrary, FFP2 should be reserved for healthcare workers performing invasive medical procedures on the respiratory sphere that may generate an aerosol, such as non-invasive ventilation, nasopharyngeal sampling, endotracheal aspiration, functional respiratory explorations... [START_REF] Lepelletier | What face mask for what use in the context of COVID-19 pandemic? The French guidelines[END_REF] Compliance was assessed on the basis of several criteria:

• Only one face mask must be worn

• The face mask must cover the nose and mouth, it must not be worn under the chin or on the hair • Two ties or elastics must be placed for the mask to be well positioned (surgical mask and FFP2) and to maintain airtightness (FFP2)

• The face must be hairless under a FFP2 to maintain the airtightness • The face mask must not be touched or manipulated

• A FFP2 mask must be worn if the picture was taken during an invasive procedure • Tissue masks or other barrier masks are not recommended for healthcare workers during cares.

Mask wearing was considered as non-compliant if one of the above criteria was not respected.

Compliance was assessed by two hygienist doctors independently. In case of disagreement, the photographs were reviewed and a collegial decision was taken.

Results

We collected 120 different photographs after exclusion of foreign ones. We also paid attention to exclude general public photographs. In case of doubt concerning the occupation of the subject or its nationality, the file was excluded. A total of 238 healthcare workers were represented wearing masks.

The number of photographs collected by website is presented in table I.

Finally, 85 photographs (70.8%) were classified as compliant, and 35 (29.2%) as noncompliant. As several healthcare workers could be seen in a picture, we also classified 38 (16%) mask wearing as non-compliant, out of a total of 238 (Table I).

Among non-compliant photographs, 18 showed healthcare workers wearing a mask under the chin, 3 of them showed 2 different masks worn at the same time, 12 masks were not well placed or could not have been airtight because of mispositioned elastics, 1 FFP2 was worn on a beard, 2 were touched by the professional, and 1 surgical mask was worn during an aspiration which is an aerosol-generating procedure. Some of the photographs presented more than one non-compliant criterion. Furthermore, 26 were taken during direct care to patients, whereas 9 represented healthcare workers, some of them being key opinion leaders, during an interview (Table II).

Discussion

Mask wearing is a useful barrier to protect healthcare workers against droplet-transmitted virus such as SARS-CoV2, responsible for Covid-19. However, to be effective, masks must be used in accordance with good practice recommendations. Surgical face masks, FFP2 or N95 face masks are single-use products. They should be thrown away after handling and should not be kept around the neck between two treatments. Our study demonstrated an important non-compliance of mask wearing among pictures of healthcare workers published on some of the main French media websites, as 35 photographs out of 120 assessed during the period, were classified as non-compliant. The main errors described in this study are already known and commonly found in daily practice. The most frequent error seen in the photographs is the wearing of the surgical mask under the chin, as a bib. These masks are kept around the neck in order to be reused quickly. However, masks can paradoxically represent a possible way of contamination when misused. Handling them can damage their filter membrane and reduce the level of protection. Their external face can also be contaminated by virus which can end up on the caregivers and then be transmitted to other patients. Public masking spread in the population in the perspective of personal protection. However, the general population is not trained in the use of masks even if there are recommendations published by WHO [START_REF]When and how to use masks[END_REF]. They therefore tend to copy what they observe in the media and may base their behaviour on the professionals they see in action. Knowledge on recommended carrying times and fragility of these devices is not well spread. Moreover, mistakes in mask positioning are frequently observed in the general public: for example, masks not covering entirely the nose or the mouth, and thus ineffective.

Media websites are a huge way of disseminating information, reaching a large audience.

Mass media campaigns can change human health behaviours [START_REF] Wakefield | Use of mass media campaigns to change health behaviour[END_REF]. One can hypothesize that information disseminated through media may impact the population behaviour on mask wearing. This can be especially true when the observed behaviour is the key opinion leader's one. We have unfortunately observed that several portraits staged in the press concern medical professors who wore their surgical mask as a bib, which is also a frequent mistake in the general population.

In France, the errors observed could be also linked to divergent speeches made by the government concerning the value of the mask. During the lockdown period the mask wearing in the general population was not recommended for asymptomatic persons. When people observed that all healthcare workers systematically wore a mask to prevent Covid-19, they felt the need to wear one themselves. Healthcare establishments were quickly faced with shortages of masks which forced institutions and learned societies to review its use indications. This has resulted in an increased mask wearing time and restrictions on the use of FFP2 masks. The French Hygiène society, SF2H, allowed caregivers to keep the same FFP2 mask up to 8 hours maximum and to keep the same surgical anti-projection mask for up to 4 hours maximum [START_REF] Kampf | COVID-19-associated shortage of alcohol-based hand rubs, face masks, medical gloves and gowns -proposal for a risk-adapted approach to ensure patient and healthcare worker safety[END_REF]. Moreover, the nursing staff had to use very different materials throughout the epidemic. To cope with the shortage of masks, establishments had to order many different brands of masks and they found themselves using equipment of very uneven quality.

The scale of the epidemic has led to the saturation of healthcare services. Healthcare workers were sometimes overwhelmed by care and had little or no available time to attend training on the use of personal protective equipment. In addition, hospital hygiene teams are often small and have had to cope with a very large demand for training in the field. The equipment usually used for care was no longer available and it was complicated to train the entire hospital to use the new equipments.

We did not observe the use of fabric masks in a care situation. The use of this kind of mask which does not provide a sufficient level of protection is not recommended by learned societies [START_REF] Kampf | COVID-19-associated shortage of alcohol-based hand rubs, face masks, medical gloves and gowns -proposal for a risk-adapted approach to ensure patient and healthcare worker safety[END_REF]. However, their use is widespread in the general population, especially since the end of confinement in France. Even if its wearing rules are not as strict as those of surgical masks or FFP2, its use cannot be improvised. The general population has never been trained in their use and therefore may copy behaviors observed in the media. Some of these masks made at home have no effectiveness in terms of protection because their level of filtration is not sufficient. Others, available in shops, meet AFNOR standards but must be used in accordance with the recommendations to be effective. The systematic wearing of the mask in public space is not compulsory but some municipalities have attempted to impose it by municipal decrees. It is however compulsory in public transport in large cities like Paris.

Masks are certainly an effective protection in these conditions to prevent the spread of the Covid-19 epidemic.

Our study has some limitations. The websites of the main French newspapers are not the only media where the wearing of masks is visible. Television news and report magazines expose the general public to this style of image extremely frequently. We could not assess the compliance of mask wearing in the reports broadcast in videos by lack of means. We felt that the websites were a representative sample of what can be seen in news magazines. These are very popular sites that reach a relatively large audience. It would be interesting to conduct this type of study in other countries, and to assess mask wearing in television programs. Health authorities should communicate widely about the good practices for mask wearing in general population. BFMTV.com https://www.bfmtv.com/international/en-italie-plus-de-150-medecins-sont-morts-du-coronavirus_AN-202004270261.html [START_REF]En Italie, plus de 150 médecins sont morts du coronavirus[END_REF] A healthcare worker phoning with a mask

Liberation.fr https://www.liberation.fr/france/2020/04/30/est-il-sidifficile-en-medecine-de-dire-je-ne-sais-pas_1786919 [START_REF] Lehmann | Est-il si difficile en médecine de dire "je ne sais pas" ?[END_REF] Masks worn as a bib by key opinion leaders

Liberation.fr https://www.liberation.fr/checknews/2020/03/26/cetteprofesseur-critique-des-methodes-de-didier-raoultest-elle-en-conflit-d-interet-avec-les-labor_1782911 [START_REF] Leboucq | qui critique des méthodes de Didier Raoult, est-elle en «conflit d'intérêt» avec les laboratoires concurrents ? Libération[END_REF] Masks worn as a bib by key opinion leaders

Lefigaro.fr https://www.lefigaro.fr/actualite-france/coronavirusles-portraits-de-soignants-au-front-a-l-hopitalgeorges-pompidou-a-paris-20200404 [START_REF] Figaro | Coronavirus : les portraits de soignants au front à l'hôpital Georges-Pompidou à Paris[END_REF]

Table I :

 I Characteristics of observed photographs

			Number	Percentage
	Photographs per Journal Le Monde	10	8%
		Le Figaro	19	16%
		Libération	15	13%
		L'Obs	9	8%
		Le Point	7	6%
		L'Express	14	12%
		BFM TV	13	11%
		C News	16	13%
		Le Télégramme	17	14%
	Photographs	Compliant	85	71%
		Non-compliant	35	29%
	Wearing of masks	Compliant	200	84%
		Non-compliant	38	16%
	Cause of non compliance Position : under the chin	18	47%
		Two masks worn	4	11%
		Elastics unplaced	12	31%
		Beard with FFP2	1	3%
		Touched mask	2	5%
		Wrong type of mask	1	3%
	Context of observation	During healthcare	26	74%
		Interview	9	26%

Table II :

 II Illustration of the main face coverings errors published on French information websites

	Example	Webside	Web link	Reference
	A healthcare
	worker wearing
	two masks at
	the same time


A El Vally

M.S Mohamed Abdallahi Bollahi

Ahmedou Ould

J Salem

P Deida

L Parola

A El Basco

M Bara

A Ouldabdallahi

Mohamed Salem Ould

Boukhary

Abdallahi El

Mohamed Salem Ould

Ahmedou Salem

Jemila Deida

Philippe Parola

Leonardo Basco

Ahmed El Bara

Mohamed Ouldadallahi

Ali Ould

Mohamed Salem Boukhary

Mohamed Ali Salem Ould

Retrospective overview of a COVID-19 outbreak in Mauritania

Keywords: Severe acute respiratory syndrome coronavirus 2, COVID-19, Mauritania, epidemiology, West Africa, preventive measures

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

In December 30, 2019, an uncommon pneumonia outbreak of unknown etiology was reported in Wuhan (province of Hubei), China [START_REF] Who | Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19[END_REF]. Viral isolation and molecular analyses indicated a novel coronavirus (family Coronaviridae) provisionally named 2019-nCov [START_REF] Huang | Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China[END_REF].

The International Committee on Taxonomy of Viruses (2020) later designated the virus 'Severe Acute Respiratory Syndrome Coronavirus 2' (SARS-CoV-2), and the World Health Organization (WHO) officially named the associated disease '2019-Coronavirus Disease' (COVID-19) [START_REF]Coronaviridae Study Group of the International Committee on Taxonomy of Viruses. The species Severe acute respiratory syndrome-related coronavirus: classifying 2019-nCoV and naming it SARS-CoV-2[END_REF][START_REF] Wang | Review of the 2019 novel coronavirus (SARS-CoV-2) based on current evidence[END_REF].

Due to its high infectiveness and person-to-person mode of transmission [START_REF] Li | Clinical characteristics of 25 death cases with COVID-19: A retrospective review of medical records in a single medical center, Wuhan, China[END_REF], the SARS-CoV-2 rapidly spread across China to other countries worldwide, and the WHO emergency committee declared on January 30, 2020, the coronavirus outbreak a global health emergency and a pandemic on March 11, 2020 [4]. As of October 09, 2020, the number of globally confirmed cases and deaths reached 36,625,213 and 1,063,381 in 224 countries, respectively [START_REF]Coronavirus resource Center[END_REF]. Africa accounts for 3.3% and 2.3% of the global cases and deaths, respectively [START_REF] Who | [END_REF]. COVID-19 pandemic is still spreading nine months after the first Chinese reported cases.

In Mauritania, a West African country, the first case of COVID-19 was diagnosed on On April 18, 2020, Mauritania officially announced that the country is coronavirusfree, after the last active case had recovered. However, following a 40-day 'COVID-19-free' period, during which only two cases were registered, the disease resurged on May 12, 2020, and since that time, COVID-19 cases have been registered daily.

In the present study, we address the current situation of COVID-19 in Mauritania, as of July 1, 2020, and discuss the efforts of Mauritanian authorities to combat this potentially life-threatening respiratory illness.

Patients and methods

Patient recruitment and data sources

Treatment

The Mauritanian authorities adopted two 'experimental' regimens for the management of oxygen-dependent, symptomatic COVID-19 cases who do not require intensive care: chloroquine or hydroxychloroquine, with or without azithromycin, or lopinavir/ritonavir combination.

Statistical analysis

Proportions were compared using Fisher exact test. Pearson coefficient correlation was used to assess the relationship between the number of COVID-19 tests performed and the number of COVID-19 positive cases. A P value <0.05 was considered statistically significant.

Computations were performed using MedCalc software for Windows, version 15.0 (MedCalc Software, Ostend, Belgium).

Results

Overall, 41,862 tests for Sars-Cov-2 were performed by July 1, 2020, with a mean of 377 tests per day during the study period (n = 111 days), and an average of 798 tests/day for the last 48 days. Of 41,862 tested individuals, 4,472 (10.7%), corresponding to an incidence rate of 1.1/1,000 persons, were positive for SARS-Cov-

Discussion

Using the national case-based surveillance, the present study describes the epidemiological feature of COVID-19 outbreak in Mauritania. A low rate of mortality (2.9%) due to COVID-19 was observed during the period between March 13 and July 1, 2020 in Mauritania. This result is within the range of 1.6-6.5% reported for the same period in some neighboring countries of Mauritania, such as Senegal (1.6%), Morocco (1.8%), Mali (5.3%), and Algeria (6.5%) [START_REF]COVID-19 rapport de situation[END_REF]. Consistent with reports on morbidity and deaths in individuals with COVID-19, the majority of positive patients were males (56.6%) and most deceased patients (72%) were aged ≥ 55 years [START_REF] Who | Clinical management of COVID-19[END_REF][START_REF] Chen | Clinical characteristics of 113 deceased patients with coronavirus disease 2019: retrospective study[END_REF]. Mauritania has a young population with a majority of its inhabitants belonging to the age group between 24 and 45 years old [START_REF] Guilmoto | COVID-19 death rates by age and sex and the resulting mortality vulnerability of countries and regions in the world[END_REF], which corresponds to the most affected individuals during the current epidemic. However, young people have been reported to be less susceptible to COVID-19 infection than older people aged ≥ 55 years [START_REF]Annuaire statistique[END_REF]. This is consistent with the high rate of asymptomatic individuals (84.6%) observed among young persons in this study and could be a favorable condition in limiting the mortality rate of the disease. This assumption is supported by a recent study showing that only a small proportion (within the range of 0-10%) of asymptomatic carriers eventually develop symptoms of COVID-19 [START_REF] Zhao | Incidence, clinical characteristics and prognostic factor of patients with COVID-19: a systematic review and meta-analysis[END_REF].

Although the first case of COVID-19 was reported on March 13, 2020, the exponential growth phase in the number of positive cases was observed only from June. This could be due to the fact that the majority of initial cases of COVID-19 were detected among foreigners who had little contact with Mauritanians and the rapid riposte of the health authorities to trace few positive individuals who were in contact with them. The opposite situation was observed after the 40-day 'COVID-19-free' period, during which death of Mauritanians, who apparently had no history of contact with a COVID-19-infected patient, was announced. Increasing growth observed during June could be due to the exponential number of persons tested for COVID-19 during contact tracing.

During the study period, a relatively low prevalence (10.8%) of COVID-19 was detected in Mauritania. Although the age distribution of infected patients was similar to that of the general population in Mauritania, the reported prevalence could be biased because the study population mostly consisted of individuals identified during contact tracing, which may not necessarily represent the general population. To overcome the possible weakness in the reported prevalence, a population based-data on COVID-19 using immunodiagnostic tests that are rapid, less expensive, and easier-to-use than PCR assay in the field are urgently needed.

Moreover, because COVID-19-infected individuals can have mild illness or may be asymptomatic (and therefore might not be tested for diagnosis or receive medical care), COVID-19 sero-prevalence surveys based on the detection of specific antibodies against SARS-CoV-2 could be more informative about the proportion of persons who have been infected with SARS-CoV-2. These surveys are also suitable and useful for disease surveillance [START_REF] Oran | Prevalence of asymptomatic SARS-CoV-2 infection: A narrative review[END_REF].

To combat COVID-19 epidemic, preventive control measures were rapidly implemented in Mauritania. As a riposte against COVID-19, the Mauritanian authorities through an inter-ministerial committee announced a set of preventive measures, including closure of land and air borders, night curfew, closure of markets, restaurants, cafeterias, schools and universities, prohibition of prayer in mosques, and restriction of population movement between cities. Control measures included the systematic testing of symptomatic patients, isolation and management of active cases, and contact tracing and quarantine of persons who had been in contact with a confirmed COVID-19 individual to prevent onward transmission. A call center received and processed thousands of calls daily. Also, despite a mediatic controversies, chloroquine or hydroxychloroquine, with or without azithromycin, has been approved as a first line treatment of confirmed COVID-19 cases in many African countries, and was included in the regimen against COVID-19 in Mauritania [START_REF] Pollán | Prevalence of SARS-CoV-2 in Spain (ENE-COVID): a nationwide, population-based seroepidemiological study[END_REF][START_REF] Million | Chloroquine and COVID-19: a western medical and scientific drift?[END_REF]. However, as for most national health system in developing countries, Mauritanian national health system was clearly not prepared to manage a sanitary crisis of such magnitude.

March 13 ,

 13 2020, in a 40-year-old Australian expatriate traveling from abroad. Few days later, a second COVID-19 case was diagnosed in a 41-year-old foreign female domestic worker who returned from Senegal 10 days before she was diagnosed. A third positive case was reported on March 26, 2020, in a 74-year-old man who had returned from France 10 days earlier. The first death associated with COVID-19 occurred on March 30, 2020, in a 48-yearold French-Mauritanian woman who tested positive post-mortem. The woman had been quarantined alongside 16 other individuals who arrived in mid-March 2020 in one of the last flights from France before Mauritanian authorities banned international arrivals.

  There were three pathways through which the Mauritanian Ministry of Health recruited Covid-19-positive cases: (i) the mobile alert management teams (ii) sentinel reception sites created n collaboration with the army, and (iii) patients attending health facilities with suspected COVID-19 signs and symptoms. Regional hospitals throughout the country sent nasal swab samples/blood samples of symptomatic patients for RT-PCR/serological tests to Institut National de Recherches en Santé Publique (INRSP) in Nouakchott where diagnostic tests were centralized. During the period from March 13 to July 1, 2020, demographic, clinical, laboratory, and raw outcome data of COVID-19-positive patients from all regions of Mauritania were obtained from the daily COVID-19 situation reports officially co-published by the Mauritanian Ministry of Health and the WHO country Office in Nouakchott [8] and data available online [9]. The daily press briefings of the Ministry of Health were also available on the official site of the national television. Case definitions of suspected cases Based on the evolving situation of COVID-19, the scientific committee comprising 11 scientists and clinicians established a national guideline for COVID-19 clinical management, including case definition and treatment regimen. A COVID-19 'suspected case' was defined as any individual with clinical signs of acute respiratory infection, fever (suspected or measured), or symptoms associated with COVID-19 infection [10]. 'Probable case' was defined as any individual with symptoms compatible with COVID-19 and had close contact with a confirmed case of COVID-19 within the past 14 days. 'Confirmed case' was defined as a symptomatic patient or asymptomatic carrier with laboratory confirmation of infection with SARS-CoV-2 using a PCR-based assay. Diagnostic methods Implementation of the COVID-19 diagnostic testing started from February 12, 2020 using serological and PCR-based approaches. Serology was performed by SARS-CoV 2 IgG/IgM rapid diagnostic test (RDT; Xiamen Biotime Biotechnology, Fujian, China). SARS-COV-2 molecular diagnosis was performed using Daan real-time fluorescent-PCR kits for 2019 Novel Coronavirus RNA detection (DAAN gene Co. Ltd., Sun Yat-Sen University, Guangzhou, China) Both serological tests and RT-PCR were performed at the "Laboratoire de Virologie", INRSP, Nouakchott.

Figure 2

 2 Figure 2 illustrates the daily number of COVID-19 tests performed and the number of

  For instance, a very limited number of beds in intensive care units existed in health facilities before the COVID-19 outbreak. According to the daily COVID-19 situation report of the Ministry of Health, there are several areas where reinforcement is necessary, including testing facilities, qualified laboratory technicians, health care capacity, and personal protective equipment to overcome COVID-19 outbreak.

Figure 1 .Figure 2 .

 12 Figure 1. New daily confirmed cases of COVID-19 in Mauritania from March 13 to July 1,

  2, including 1,377 confirmed by RT-PCR, 2,561 by RDT, and 534 by both methods of diagnosis. Males were significantly more affected (57.1%; 2,554/4,472) than females (42.9%; 1,918/4,472) (P < 0.0001) (Table 1). Individuals of the age groups 15-34 and 35-54 years were the most affected with 1,602 (35.8%) and 1,635 (36.6%) positive cases, respectively. The disease resulted in 129 (2.9%) deaths, corresponding to a mortality rate of 3 deaths/100,000 persons, 1,677 (37.5%) recoveries, and 2,666 (59.6%) active cases. There were no data on the disease severity among 1,677 recovered COVID-19 patients. Of 2,666 active cases, 2,261 (84.8%) were asymptomatic carriers, 394 (14.8%) symptomatic patients with mild symptoms, and 11 (0.4%) severe cases. All patients who died (n = 129) were symptomatic and had severe symptoms. Data from 118 (91.5%; 11 missing data) of 129 deceased patients indicated that COVID-19-associated mortality was significantly higher in men (61.0%; 72/118) than in women (39.0%; 46/118; P = 0.02) and that 72.0% (85/118) of persons who died were adults aged ≥ 55 years (data not shown).

	Of 4,472 positive cases, 4,241 (94.8%) were infected through close contact with a
	COVID-19 patient, 133 (3%) had apparently no contact with confirmed COVID-19 case (i.e.
	cases in which authorities were unable to trace the source of the infection), and 98 (2.2%)
	were imported. Of 2,666 COVID-19 active cases, 2,283 (85.6%) were from Nouakchott, the
	capital city. There were no clear indications as to whether 1,667 recoveries from COVID-19
	occurred after treatment with the recommended 'experimental' regimens or by spontaneous
	recovery.

Table 1 .

 1 Demographic and clinical characteristics of patients with COVID-19 in Mauritaniabetween March 13 and July 1, 2020 , number of cases; There were a total of 4,472 COVID-19-positive patients, as of July 1, 2020. We were not able to obtain data on disease severity among patients who recovered.

	Characteristics	n (%)
	Gender
	Male	2,554 (57.1)
	Female	1,918 (42.9)
	Age groups (year)
	0 -14	275 (6.1)
	15 -34	1,602 (35.8)
	35 -54	1,635 (36.6)
	≥ 55	960 (21.4)
	Disease outcome
	Active cases	2,666 (59.6)
	Recovery	1,677 (37.5)
	Death	129 (2.9)
	Disease severity among active cases*
	Asymptomatic	2,261 (84.8)
	Mild symptoms	394 (14.8)
	Severe symptoms	11 (0.4)
	Source of infection
	Contact with confirmed case	4,241 (94.8)

n

Funding

Published with the support of the French Embassy in Mauritania, AILARA project, and grant number 2018-2079.

Availability of data

Data sharing not applicable to this article as no datasets were generated during the current study.

Ethics approval and consent to participate

Not Applicable.

Consent for publication

Not Applicable.

Declaration of competing interest

The authors declare no conflicts of interest.

Author contributions

AV, MAB, AB, SML, JD, MSOAS, and MO collected data from the different sources. AOMSB, LB, and PP analyzed data, wrote the manuscript and approved the final draft. All authors read and approved the final manuscript.