Nasopharyngeal and hypopharyngeal carcinoma risk among immigrants in Sweden.

Environmental exposures, particularly infection with Epstein-Barr virus (EBV) and tobacco, are known risk factors for oral cancer. Studies in migrants may provide valuable insight into the environmental and genetic etiology of cancer. We wanted to define nasopharyngeal and hypopharyngeal carcinoma among immigrants in Sweden. The nationwide Swedish Family-Cancer Database (FCD) was used to calculate standardized incidence ratios (SIRs) for nasopharyngeal and hypopharyngeal carcinomas among the first-generation immigrants compared to the native Swedes. The FCD included 1969 and 691 cases of nasopharyngeal and hypopharyngeal carcinoma in the male and female Swedes and 178 and 65 cases in immigrants, respectively. The median age at diagnosis (years) was 63 among Swedes and 55 among immigrants. The risk of nasopharyngeal carcinoma was significantly higher in male (SIR = 35.6) and female (24.6) Southeast Asians, male (12.4) and female (34.7) North Africans, male (4.9) and female (10.9) Asian Arabs and some other male Asians immigrants (6.2 to 6.7). Among immigrants from European countries, only the men from former Yugoslavian showed an elevated risk (2.7). Hypopharyngeal carcinoma risk was only increased among the male immigrants from the Indian Subcontinent (5.4). Early life infection with EBV in countries of origin and probably a minor contribution by tobacco smoking may be the main environmental exposures influencing nasopharyngeal carcinoma risks among immigrants to Sweden. The high rates of hypopharyngeal carcinoma among Indian immigrants may point to a continued using of smokeless tobacco.