Familial risk and clustering of nasopharyngeal carcinoma in Guangdong, China.

Background: Previous studies have suggested that genetic susceptibility may play an important role in the etiology of nasopharyngeal cancer (NPC). However, to date, few large-scale studies have been conducted on familial risk and clustering of NPC in a high-risk area of China.

Methods: In the current study, 2252 patients with NPC who were treated at the Cancer Center of Sun Yat-Sen University in Guangdong Province, China, were identified as probands. Family histories of NPC and other malignancies were observed in first-degree relatives (FDRs) and second-degree relatives, and other information was obtained through interviews. One thousand nine hundred and three Cantonese families were selected for further investigation. To assess familial aggregation, the authors used standardized incidence ratios (SIRs) to measure the risk of NPC for FDRs and compared the observed number of cases with the number predicted by population-based frequencies in the Cantonese population of Hong Kong.

Results: The current analysis indicated that families with > or = 3 relatives who had NPC were distributed predominantly among a high-risk subgroup of the Cantonese population in Guangdong Province and that the frequency of these families was 0.68%. An SIR of 2.09 (95% confidence interval [CI], 1.80-2.40) was observed among 13,833 FDRs in the high-risk subgroup, and a significantly elevated risk for NPC was observed in FDRs of probands with early age of onset (age < 40 years; SIR, 9.01 [95% CI, 6.10-13.30]). Furthermore, decreased risks of hepatic, lung, esophageal, gastric, and breast carcinoma, as well as malignancy of all sites, were observed among FDRs of probands with NPC when Hong Kong and Shanghai populations were used as reference groups.

Conclusions: NPC tends to aggregate in Cantonese families in Guangdong Province, and the malignancies in these families appear to be site specific, with no excess of any other malignancy.