Nasopharyngeal carcinoma in Ibadan, Nigeria: a clinicopathologic study

Introduction nasopharyngeal carcinoma is relatively common in our environment. It is one of the most difficult malignancies to diagnose at an early stage. The aim of the study was to determine the clinical features, clinical disease stage of nasopharyngeal carcinoma at presentation and at diagnosis as well as the histologic types at the University College Hospital, Ibadan, Nigeria. Methods this was a ten year retrospective study of all histologically confirmed nasopharyngeal carcinoma between January 2007 to December 2016 using clinical and pathology records and files. Results there were 73 cases. The male: female ratio was 1.7. The age of patients ranged from 12 to 80 years with a mean age of 39 ± 16 years. The median age at diagnosis was 40 years. The peak age group of occurrence was 40-49 years. The most common symptoms were namely epistaxis in 67.1% of patients at presentation, neck mass/swelling (64.4%) and nasal mass/obstruction (63.0%). Majority (54.8%) of the patients presented late with stage 3 or 4 disease. Most (94.5%) of the tumours were of the non-keratinizing squamous cell carcinoma subtype. The keratinizing and basaloid variants accounted for 4.1% and 1.4% of the tumours respectively. Conclusion vague, non-specific symptoms make patients present at late stages of the disease, making it almost impossible to attempt cure. The dominant histopathological type is non-keratinizing squamous cell carcinoma and resembles that seen in most parts of Nigeria and endemic areas of the world.


Introduction
Nasopharyngeal carcinoma (NPC) is defined by the World Health Organization (WHO) as carcinoma arising in the nasopharyngeal mucosa showing light microscopy and ultrastructural evidence of squamous differentiation [1]. Based on the current WHO classification of tumours of the nasopharynx, the three histomorphologic types are namely keratinizing, non-keratinizing (differentiated and undifferentiated; formerly WHO Grade II and III respectively) and basaloid squamous cell carcinoma [1]. It is a common cancer and leading cause of morbidity and mortality in well-defined populations of the world especially in natives of Southern China, Southeast Asia, the Arctic and the Middle East/North Africa [2]. The distinctive racial/ethnic and geographic distribution of NPC worldwide suggests that both environmental factors and genetic traits contribute to its development [2]. The Globocan statistics on cancer incidence worldwide for 2018 gave an age standardized incidence and mortality of 1.5 and 0.84 per 100,000 respectively for NPC, with a 5 year prevalence rate of 4.4 per 100,000 [3][4][5]. In NPC endemic countries and regions of the world such as Southern China, Hong Kong and Greenland, incidence rates are as high as 25-50 per 100,000 [3][4][5].
Generally in the endemic regions of the world the disease has a peak incidence in the 50-59 age group and then decline, in contrast to low risk population where there is a gradual increase in the incidence rate with increasing age [1,2,6]. Clinically, NPC typically run a long course of asymptomatic disease and usually the effect of loco regional disease like metastasis to cervical lymph nodes or cranial palsies are the first presentation of the disease, hence patients tend to present for the first time with advanced disease and poor prognosis [1,2,[7][8][9][10][11][12][13]. The origin of NPC, its presentation, histopathological types, treatment and prognosis differ from those of other malignant neoplasm originating from the upper aerodigestive tract [8].

Discussion
The male to female ratio in this study was 1.7:1. This is in keeping with studies from different parts of the world including Nigeria that shows that the disease predominantly affects men in both endemic and non-endemic populations with ratio as high as and superiorly [30]. Therefore, the anatomic spread will determine the stage at presentation. As illustrated in a review by Petersson [ [8,11,15,31]. The reason from the differences in percentage of patients presenting at different stages cannot be easily distilled out from these studies but can only be ascribed to a more aggressive course of disease prior to presentation. Tumour burden as reflected by the TNM stage is the most significant factor in terms of prognosis in NPC [1,2,6,7,35].

Conclusion
Nasopharyngeal carcinoma in our locale is not very rare. The diseases occur predominantly in males with peak age incidence in the 40-49 • Typically run a long course of asymptomatic disease; • Three histomorphologic types by the WHO are namely keratinizing, non-keratinizing and basaloid.

What this study adds
• Histomorphologic pattern in a non-endemic area is similar to that of an endemic area; • Majority of patients in our cohort presented with epistasis; • Just about half of patients in our cohort presented with stage III and IV disease.

Competing interests
The authors declare no competing interests.