Epidemiological, Clinicopathological and Prognosis Features of Moroccan Patients with Nasopharyngeal Carcinoma

Proposal: A distinct epidemiology, etiology, clinical characteristics, and therapeutic outcomes characterize nasopharyngeal carcinoma (NPC) from other head and neck cancers. An actualized analysis of NPC patients’ features enables a global view of NPC management. Accordingly, the current study investigated the epidemiological and clinical characteristics of Moroccan patients with NPC, as well as their 4-years survival outcomes and influencing prognostic factors. Methods: We prospectively analyzed data of 142 histologically confirmed Moroccan patients with NPC between October 2016 and February 2019. Kaplan-Meier and Cox regression analyses were used to assess predictive prognostic factors related to NPC. All analyses were conducted using SPSS version 21 statistical software. Results: In the present study, a net male predominance was found, with a mean age of 44±16.3 years old. Advanced stages of NPC were observed in 64.1% of patients, and 32.4% of patients presented with distant metastasis at diagnosis. The 4-years overall survival, locoregional relapse-free survival, distant metastasis-free survival and progression-free survival were 68.0%, 63.0%, 53.9%, and 39.9%, respectively. Age, N category and distant metastasis were identified as the most important independent prognosis factors for NPC in this cohort (p<0.05). Conclusion: In conclusion, NPC affects young adults and is frequently diagnosed at advanced disease stages, impacting therefore negatively patients survival; which is in line with data from endemic areas for NPC. The current study clearly highlights that a greater attention should be directed to improving the management of this aggressive malignancy.


Introduction
Nasopharyngeal carcinoma (NPC) is a highly aggressive head and neck malignancy developed from the nasopharynx epithelium (Mlk et al., 2016). This cancer had a particular worldwide geographic distribution, its highly incident in selected geographic and ethnic populations. High endemic areas for NPC are located in southern parts of China and other parts of Southeast Asia (Malaysia, Indonesia, Vietnam), with an estimated incidence of 25-80 per 100,000 person-year. With an incidence of 16 per 100,000 per year, North African countries, natives of Artic region, Inuit of Greenland and Alaska represent intermediate incidence areas for NPC. The other parts of the world are considered as low incidence areas for NPC, with an incidence less than 1 per 100,000 person-year (Mahdavifar et al., 2016;Chang et al., 2021;Sung et al., 2021). NPC is a multifactorial cancer, involoving a combined and accumulative effect of host genetic, epigenetic, environmental and viral (Epstein Barr Virus (EBV)) risk factors (Jia and Qin, 2012;Perri et al., 2015;Dai et al., 2016).

Epidemiological, Clinicopathological and Prognosis Features of Moroccan Patients with Nasopharyngeal Carcinoma
The deep anatomy of the nasopharynx implies a sophisticated NPC diagnostic strategy, that combines physical examination, guided biopsy and several imaging modalities. Unfortunately, NPC is currently diagnosed at advanced stages, with around 11% of patients diagnosed with distant metastasis (Bossi et al. 2021). Concurrent chemoradiotherapy (CRT) with or without induction chemotherapy (CT) are the standard treatment modalities for these patients. Meanwhile, early stages of NPC are potentially curable with radiotherapy (RT) alone (Lee et al., 2012;Blanchard et al., 2015;Guan et al., 2020). To stage and predict prognosis of NPC, the Union for International Cancer Control (UICC) classification based on tumor, node, and metastasis evaluation (TNM) is commonly used. Survival of patients is influenced primarily by the stage of the disease and the treatment modality used (Lee et al., 2005). The 5-years overall survival (OS) for advanced NPC stages was reported to be between 25% to 40%, and the advent of intensitymodulated radiotherapy has significantly improved this rate to 80% to 90% (Luo et al., 2016).
In Morocco, as it is the case in endemic areas for NPC, management of NPC is one of the greatest clinical challenges faced by oncologists, and many efforts are made to ensure an early diagnosis and to optimize treatment approaches for a better management of this aggressive malignancy. In this field, an actualized analysis of epidemiologic, clinico-pathological, prognostic and biologic features of NPC will be of a great interest to better understand cancer evolution and to analyze the strengths and weaknesses of the existing strategy for better management of NPC in our country. Thus, the clinical data from Moroccan NPC patients were prospectively analyzed in order to evaluate epidemiological characteristics, 4-years patient survival and influencing prognostic factors.

Patients
From October 2016 to February 2019, 142 histologically confirmed patients with NPC were enrolled prospectively in the present study. Recruitment and treatment of these patients were carried out at Mohammed IV Center for Treatment of Cancer, Ibn Rochd University Hospital of Casablanca, Morocco. The study protocol was approved by the Ethics Committee of Ibn Rochd University Hospital, Casablanca -Morocco. Informed consents were obtained from all patients. For those under 18 years of age, consents were obtained from their parents and/or legal guardians. Socio-economic data (age, sex, childhood habitat, familial history of cancer, tobacco habits, alcohol consumption) were collected by face-to-face interviews and clinical information including (histological type, clinical presentations, TNM classification, disease stage, management timeline, imaging data, treatment regimens and survival patient's outcome) were retrieved from patients' medical records. Family history of cancer was considered when a first-degree relative (father, mother and siblings), and/or when a second-degree relative (such as grandparents, uncles, aunts, distant cousins or niece on one side or on the other of the family) had a prior history of any type of cancer. Patients were characterized as smokers when they were past or current smokers, and as drinkers when they were drinker's during the last 5 years or present drinkers.
The histopathological classifications were confirmed on the basis of the World Health Organization (WHO) criteria for Head and Neck Tumours ; NPCs were grouped into keratinizing squamous cell carcinoma (KSCC), non-keratinizing differentiated carcinoma (NKDC) and non-keratinizing undifferentiated carcinoma (NKUC). Furthermore, all patients were staged according to the 7th edition of the UICC/AJCC system. The date of treatment was defined as the time between histological diagnosis and the start date of the first treatment.

Follow-up and survival endpoints
For all patients, follow-up evaluations were performed every 3 months within the first year, every 6 months for the following 2 years, and annually thereafter. During the follow-up period, patients were regularly re-examined by medical consultation, nasopharyngoscope, head and neck MRI and/or CT, thoracic, abdominal and pelvic CT, and [ 18 F]-FDG-PET/CT.
The follow-up period was considered as the date of the first consultation in the center to either the date of death or the date of loss to follow-up or till March 31, 2021. OS was defined as the interval from the date of diagnosis to the date of death from any cause or last follow-up. Locoregional relapse-free survival (LRRFS) was defined as the interval from the date of diagnosis to the first confirmed radiological or histological locoregional relapse, death from any cause, or last follow-up. Distant metastasis-free survival (DMFS) was defined as the interval from the date of diagnosis to the first confirmed radiological or histological distant metastasis, death from any cause, or last follow-up. Progression-free survival (PFS) was defined as the time from the diagnosis to the progression of the disease, death, or last follow-up.

Statistical analysis
The epidemiological and clinical characteristics of the studied NPC patients are presented as mean values, ranges and percentages. Survival rates were determined using Kaplan-Meier method, and survival differences were compared using the log-rank test. Univariate and multivariate Cox proportional hazards regression models were used to assess prognostic factors of NPC; hazard ratios (HRs) and their 95% confidence intervals (CIs) were reported. Variables with significant differences in the univariate analysis were entered into multivariate regression models. All analyses were conducted using SPSS version 21 statistical software (IBM Corporation, Armonk, USA). Results were considered statistically significant when the p-value was less than or equal to 0.05.

Sociodemographic characteristics
The age of the 142 NPC patients enrolled in the present study ranged from 12 to 80 years, with a mean age of 44.0 ±16.3 years and a male to female (M:F) sex ratio of 1.6. The age distribution of our NPC patients showed a bimodal distribution, with a first peak occurring at 12-21 years and the second at 43-52. We observed a M:F sex ratio of 1.2 for NPC patients under 30 years of age, and of 1.8 for patients above 30 years. The cohort consisted of 52.1% patients with urban childhood habitat, and 47.9% of patients with rural childhood habitat. Of these patients, 19.0 % were smokers and 14.1% were alcohol consumers; the combination of alcohol consumption and smoking was observed in 4.9% of patients. A family history of cancer was found within 22.5% of patients, among them, 7.7% had at least one family member who treated or is treating NPC. First and second-degree family history of cancer were observed in 12.6% and 10.5% of patients, respectively, while third-degree family history of cancer was reported in one patient (0.7%) ( Table 1).

Management timeline
In the present study, the mean duration between diagnosis and initial treatment was 81.1 ± 44.2 days (d) (median of 76.5 d; [20-184 d]). In detail, the mean time between histological diagnosis of NPC and the first oncologic consultation was 29.8 ± 27.9 d (median of 25.0 d; [2-95 d]), and the average delay between the first consultation and the loco-regional extension assessment (MRI and/or CT) was 33.9 ± 33.1 d (median of 22.5 d; [3-173 d]). The delay between the first consultation and the distant extension assessment (TAP-CT and/or PET-CT) was 30.9 ± 24.6 d (median of 21.5 d; [2-95 d]

Symptoms
Initial clinical presentation consisted of one symptom in 87.3 % of the cases, and two symptoms or more in 12.6 % of patients. The onset of lymphadenopathy (66 patients) was the major symptom leading patients to an initial medical consultation, followed by the appearance of rhinologic syndrome in 52 patients (36.6%), otological syndrome in 28 patients (19.7%) and neurological syndrome in 13 patients (9.1%) ( Table 2).
Symptoms characteristics are presented in (Table 1). Out of 142 patients, 115 (81.0%) presented with neck lymph nodes; the lymph node was unilateral in 62 patients (43.7%) and bilateral in 53 patients (37.3%). The second most commonly reported symptom was headache, which found in 107 patients (75.4%). The most common rhinologic symptoms were nasal obstruction observed in 83 patients (58.5%) and epistaxis in 77 patients (54.2%), while rhinorrhea was reported in 35 patients (24.6%). The otological syndrome was observed among our patients, and was manifested by earache in 95 patients (66.9%) and otorrhea in 23 patients (16.2%). Neurologic manifestation was noted in 39 patients (27.5%). Figure 1 depicts the Kaplan-Meier plots to illustrate the survival of all patients and demonstrate the association between survival and patient characteristics. The mean follow-up period was 28.  The effect of smoking and alcohol consumption on the different end-points of survival was further assessed. We showed that smoking was not significantly associated with OS, LRRFS, DMFS, and PFS (p>0.05). However, alcohol consumption was significantly associated with OS, DMFS and PFS (p<0.05).

Multivariate analysis
In multivariate analysis (Table 5), the 4-years OS was impacted significantly by alcohol consumption (p=0.01), N (p=0.03) and M (p=0.000) category's. Our data further show that better 4-years LRRFS was significantly associated with young age (p=0.01), no

Discussion
The present study showed that most NPC patients were males with a M:F sex ratio of 1.6. This finding is in agreement with widely reported data showing that independent of race and ethnicity, NPC is more incident in males than females (Xie et al., 2013). The reasons behind this is still unclear; although it has been suggested that this   can be partially due to differential exposure between sex to environmental risk factors (Yuan et al., 2000;Zou et al., 2000). Recently, several studies reported a significant change in the percentage of female patients between young and adult NPC cases (Andejani et al., 2004;Xie et al., 2013). Accordingly, we observed juvenile cases for whom the M:F sex ratio was near equilibrium (1.2) while in cases above 30, there was an imbalance with a M:F sex ratio of 1.8. Published data report that the age incidence of NPC differs between populations. In high and low-risk ares for NPC, the incidence increases monotonically with age; the incidence peaks are currently around ages 45 to 59 years and declines thereafter, with limited cases of juvenile cases (Liu et al., 2014;Zhang et al., 2015). For intermediate risk populations, the age incidence curve for NPC shows a bimodal distribution with a significant peak between 10 and 25 and a second peak around ages 50 to 59 years old (Daoud et al., 2003;Spano et al., 2003). A similar bimodal age distribution of NPC was observed in our cohort, with a high proportion of young individuals (≤30 years old), suggesting the involvement of exposure to oncogenic agents early in life, and the potential impact of genetic susceptibility. In the present study, 19.0% of NPC patients were smokers and 14.1% were alcohol consumers. The impact of tabacco smoking and NPC development is controversial. Some authors reported that, in contrast to the other head and neck cancers, tobacco smoking and alcohol consumption are less involved in the development of NPC (Jethwa and Khariwala, 2017;Goffinet et al., 2019), whereas others suggested that cigarette smoking can promote carcinogenesis in the normal nasopharyngeal epithelium and is associated with higher NPC mortality Lin et al., 2015). Results of a large meta-analysis provided robust evidence that tobacco smoking is one of the most important risk factors for NPC (Xue et al., 2013).
Reported data showed that alcohol drinking is a useful predictor of prognosis in male NPC patients; drinkers, especially heavy drinkers, have poorer prognosis (Chen et al., 2016). In the present study, multivariate analysis revealed an association between alcohol consumption and worse LRRFS, DMFS and PFS.
Family history of NPC has consistently been associated with an increased risk of developing NPC in high risk populations for NPC (Bei et al., 2012;Xie et al., 2015). Unfortunately, there are few data regarding family history of NPC in Morocco. Recent studies have reported a relationship between family history of cancer and tumor progression (Rehioui et al., 2019) and circulating EBV DNA load (Gihbid et al., 2021). In the present study, family history of cancer was found within 22.5% of patients, among them 8.4% had at least one family member who treated or is currently treating NPC. These results are in agreement with data from high risk populations for NPC, reporting close rates of positive family history of NPC (3.64% to 11.7%) within NPC patients Wang et al., 2017).
Worldwide, diagnosis of NPC at advanced stages is the main problem that oncologists face in NPC management, which has a considerable impact on therapeutic success and patient survivals (Abdullah et al., 2009). Assessment of disease stage reported that most patients were diagnosed at an advanced stage (III,23.9% and IV,64.1%); while only few patients diagnosed at an early stage of the disease (I,2.1% and II,9.9%). Furthermore, a high rate of DM was detected among our patients (32.4%) which was comparable to that observed in high endemic areas for NPC (Wei and Sham, 2005) (Chang and Adami, 2006).
Currently, limited data regarding the prognosis of NPC from intermediate risk-population are available. Thus, we assessed 4-years patient survival and influencing prognostic factors in the Moroccan context, where this malignancy occurs at an intermediate risk. The overall prognosis of recruited patients was poor, with very low rates of DMFS and PFS (53.9% and 39.9% at 4 years). These results go beyond previous reports from other studies, highlighting that NPC is a particular tumor with a high rate of regional recurrence and DM Marnouche et al., 2017). The prognostic impact of gender in NPC is still controversial. Some studies highlighted that being female was a favorable factor, and female NPC patients were less exposed to have DM and exhibited superior OS and PFS rates compared to male patients (Lu et al., 2013;Xiao et al., 2013). Whereas other studies reported no significant difference in survival between the two sexes (Lee et al., 2005;Yunsheng et al., 2008). In the present study, we showed that females with NPC tend to have better OS, DMFS and PFS rates than males, although the difference was not statistically significant.
Previous reports studying the prognostic impact of age in NPC showed that disease-related survival, local control and DM were significantly affected by age (Liu et al. 2008;Yunsheng et al., 2008;Xiao et al., 2013). Similarly, multivariate analysis indicated that advanced age was an independent predictor factor for poor LRRFS, DMFS and PFS (p=0.03). The increased NPC related deaths and disease progression observed in older patients can be related to the poor performance status and/or the presence of comorbidity in this patients group (Sarfati et al., 2016).
Scientific evidence showed that the treatment of any cancer involves staging; an accurate staging will help in guiding planned treatment and will also allow clinicians to predict the prognosis. In the present study, multivariate analysis showed that T size was not an independent prognostic factor and highlighted that N status is a powerful independent prognostic factor for NPC. In fact, advanced nodal status was associated significantly with all survival endpoints [(OS: HR= 0.34 (CI: 0.12-0.94), p=0.03), (LRRFS: HR=0.32 (CI: 0.12-0.83), p=0.02, (DMFS: HR= 0.32 (CI: 0.16-0.64), p=0.001), (PFS: HR= 0.45 (CI: 0.24-0.86), p=0.01)]. In line with these results, previous studies demonstrated that the N involvement is more important than the T size in prognosis prediction (Han et al., 2010;Mak et al., 2015;Li et al., 2018;Xu et al., 2019).
Currently, it's widely accepted that DM is one of the main causes of death and the key obstacle to treatment (Ong et al., 2003;Qu et al., 2020); accordingly, our results showed that the presence of DM at diagnosis predict significantly worse OS and PFS in NPC patients (p<0.000). In multivariate analysis, disease stage was not significantly associated with NPC patient's survival. However, Kaplan-Meier showed that as the disease stage increased, the 4-years DMFS and PFS rates decrease significantly; they were at 100% for patients with stage I, 88.9% and 88.9% for patients with stage II, 78.3% and 50.5% for patients with stage III and 38.5% and 28.6% for patients with stage IV, respectively. These results were in line with those reported in previous studies (Mak et al., 2015;Li et al., 2018).
Data of our study are very informative and provides an overview of NPC patients' features and highlights the urgent need for an effective diagnostic, therapeutic and follow-up strategy for Moroccan patients with NPC. In endemic areas for NPC, screening programs are generally based on naso-endoscopy, EBV IgA serology tests, and EBV DNA levels (Tay et al., 2016). Given that survival rates are better among patients diagnosed at an early clinical stage, specifically those with non-nodal involvement; the implementation of NPC new biomarkers' into routine managment in intermediate incidence areas for NPC could be helpful to control this disease, prevent death and improve patient outcomes. In this field, it's of particular interest to assess the usefulness of recent and non-invasive tools such as EBV DNA load (Gihbid et al. 2023), high sensitive imaging (PET-MRI) for initial diagnostic and recurrence detection (Gihbid et al. 2022) and to extend personalized treatment for optimum management of these patients.
In conclusion, our study carried out in a Moroccan population shows that NPC affects young adults and it's often diagnosed at advanced stages of the disease impacting negatively the survival of patients; which was in line with the data from endemic areas. Thus, the use of novel biomarkers that could help in early diagnosis and prognoses prediction, as well as incorporating the recent treatment modality are the key factors for an efficient management of NPC in Morocco.

Funding statement
This study was funded by the Institut de Recherche sur le Cancer (IRC) Ref: 201932, and the Centre National pour la Recherche Scientifique et Technique (CNRST).

Ethical Approval
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional committee on human experimentation and with the Helsinki declaration of 1975, as revised in 1983. Protocol of the present study was approved by the Ethics Committee of Ibn Rochd Hospital of Casablanca, Morocco. A written informed consent was obtained from each patient.

Availability of data and materials
The data that support the findings of this study are available from the corresponding author, upon reasonable request.