Familial aggregation of nasopharyngeal carcinoma in Taiwan.

BACKGROUND:The incidence of nasopharyngeal carcinoma (NPC) is higher in Chinese than in Caucasian populations. Genetic, viral, and lifestyle factors may explain these ethnic differences in the incidence of NPC. In the present study, we examined the familial aggregation, heritability, and relative risks (RRs) of NPC using a nationwide database in Taiwan. METHODS:A population-based family study was conducted using the Taiwan National Health Insurance Research Database. Participants included all individuals (N=23,422,955) registered with that database in 2013; of these, 17,653 had NPC. Among them, 47.45%, 57.45%, 47.29%, and 1.51% had a parent, child, sibling, and twin, respectively, with NPC. RESULTS:Among the approximately 23 million Taiwan NHI beneficiaries in 2013, the relative risks (RRs) (95% confidence intervals) for NPC were 34.46 (5.12-231.77) for twins of the patients, 9.23 (6.34-13.43) for siblings, 3.80 (2.97-4.86) for parents, 3.74 (2.60-5.37) for offspring, and 1.78 (1.16-2.74) for spouses without genetic similarity. The mean age of onset in first-degree relative-affected NPC patients was 35.5years compared to 39.0years for NPC patients without affected first-degree relatives (p≤0.0001). Using a threshold liability model, the accountability for phenotypic variance of NPC was estimated to be 61.3% for genetic factors (heritability), 13.9% for shared environmental factors, and 24.8% for non-shared environmental factors. The probability of a patient with NPC to be sporadic was 82.8%. CONCLUSION:This population-based analysis suggested a strong familial tendency in the development of NPC. Screening of first-degree relatives of NPC patients is recommended, particularly in endemic regions.