Gender differences in risk of developing nasopharyngeal cancer (NPC) in one of the highest NPC ethnic in the world

Abstract

Background: NPC is more common in South East Asia and Southern part of China (e.g. Hong Kong) than elsewhere in the world. NPC is common in male, with reported male to female ratio ranges from 2-3: 1. Native Bidayuh has been shown to have one of the highest incidence in the world. Methods: All eligible newly diagnosed, histologically confirmed NPC cases treated at Sarawak General Hospital (SGH) from 2010 - 2016 were identified through hospital medical record. Patient's demographic characteristics, disease staging, histological diagnosis, treatments and follow up management were reviewed and analyzed. Denominators for calculation of rates are derived from the state of Sarawak census year 2017. Results: Our cohort comprised of 1102 newly diagnosed NPC cases, with 826 male (M) and 276 female (F) patients. There are 338 cases in Iban, 260 cases in Chinese, 226 cases in Bidayuh, 177 cases in Malays and 101 cases in other minority ethnics. The age-standardized rate (ASR) in Sarawak resident citizens was 9.63 in males and 3.39 in females respectively. The risk in native Bidayuh was 2.02 fold (M) [ASR 19.43] and 2.98 fold (F) [ASR 10.11] higher than the overall study population, and 3.03 fold (M) and 4.6 fold (F) higher than the known Malaysia average (6.4 in male and 2.2 in female). We are the first to report on higher risk of developing NPC in female Bidayuh than male. The stage distribution at presentation are; stage 1 (4.6%), stage II (10.3%), stage III (32.6%) and stage IV (52.5%). Most NPC patients in Sarawak presented at later stage (85% at stage III and IV) as compared to high incidence areas elsewhere. Conclusions: Native Bidayuh in Sarawak, Malaysia has one of the highest ASR of NPC in the world. We are the first to report on higher risk of developing NPC in female Bidayuh than male. Majority of patients presented late compared to other parts of the world with high incidence of NPC. Thus, measures to improve early detection of NPC for better cure rate is urgently needed in this high risk population.