Age-Incidence Curves of Nasopharyngeal Carcinoma Worldwide: Bimodality in Low-Risk Populations and Aetiologic Implications

Abstract

The distinct geographic variation in the global incidence of nasopharyngeal carcinoma reflects a complex etiology involving viral, environmental, and genetic components. The high to intermediate rates observed in endemic areas contrast markedly with the uniformly low rates seen in much of the world. An interesting epidemiologic observation is the early peak in ageincidence curves observed in certain geographically disparate populations, suggestive of distinct causal entities and the possible exhaustion of susceptible individuals from the population at a certain age. The aim of this study was to systematically evaluate the age-incidence profiles of NPC worldwide on partitioning populations according to level of risk, in an effort to provide clues about the importance of early-in-life factors and genetic susceptibility. Using data from 23 high-quality population-based cancer registries for the period 1983-1997, a key finding was the consistent pattern of bimodality that emerged across low-risk populations, irrespective of geographic location. Continual increases in NPC risk by age up to a first peak in late adolescence/early adulthood (ages 15-24 years) were observed, followed by a second peak later in life (ages 65-79 years). No such early peak in NPC incidence by age group was evident among the high-risk populations studied. These findings are discussed according to existing lines of biological and epidemiologic evidence related to level of population risk, age at diagnosis, and histologic subtype. A modified model for NPC tumor development is proposed on the basis of these observations. (Cancer Epidemiol Biomarkers Prev 2008;17(9):2356 -65)

Folate, vitamin B6, vitamin B12 and methionine intakes and risk for nasopharyngeal carcinoma in Chinese adults: a matched case–control study

“…Nasopharyngeal carcinoma (NPC) is a rare neoplasm in most countries (<1 × 10 −5 person-years), but a much higher incidence has been observed in southern China (20 − 50 × 10 −5 person-years) (1)(2)(3) . Infection with the Epstein-Barr virus (EBV) is considered a key cause of NPC (1) , but the ubiquity of EBV suggests that other cofactors, such as diet, may have a role in NPC aetiology and may contribute to the remarkable geographic variation (4,5) .…”

“…Although many other studies have found an inverse association between dietary (17)(18)(19)(20)(21)(22)(23) or blood (24)(25)(26)(27) folate and the risk for head and neck cancer, the numbers of NPC cases in these studies were generally <100. In addition, all of these studies were conducted among populations with dietary habits and NPC risks different from those of the Chinese in south China (1)(2)(3) . Thus, further study of the folate-NPC association in high-risk Chinese adults is necessary.…”

Concomitant Radiochemotherapy in the Management of Nasopharyngeal Carcinoma

“…Several randomized trials including that of the Alsaraf Intergroup in 1999 and the metaanalysis of Baujat and al. confirmed that the overall survival benefit was limited to the concomitant chemoradiotherapy group (9,10,11) . Lin and al found a benefit of concomitant radiochemotherapy in overall survival of 90%, recurrence-free survival of 92% and local control of 95% at three years (12) .…”

Nasopharyngeal Carcinoma: A 15 Year Study with Respect to Clinicodemography and Survival Analysis

“…Nasopharyngeal carcinoma (NPC) arises from the epithelial lining of the nasopharynx but frequently develops at the fossa of Rosenmuller around the ostium of the Eustachian [17], this is similar to low incidence areas [12]. The maximum incidence in 4th and 5th decade is also seen in the study of Boljesíková et al [13] India has low over all incidence of NPC which is comparable to UK with annual incidence of 0.9 per million population [1,12].…”