EPIDEMIOLOGIC INVESTIGATION OF NASOPHARYNGEAL CANCER IN MIGRANTS

A study of nasopharyngeal cancer (NPC) mortality over the period of 1970-1976 shows lower disease risk in the Guangzhou non-Guang- dong migrants. The mortality rate was 3.6 per 100,000 for the migrants and 10.9 for the local Guangzhou residents. The standardized morta- lity ratios of migrants of 5-9 years standing and more than 15 years standing were 0.31 and 0.14. Both groups had a significant level at 0.01. T'he same results showing mor'e NPC in Guangdong people were obtained in Shanghai over the period of 1965-1975. The NPC Grrtortality rate was 7.1 per 100,000 for Guangdong migrants and only 2.7 for indigenous Shanghai residents. The difference was statistically significant. The dif- ference between Guangdong migrants in Shang- hai and Yuexiu district residents in Guangzhou was insignificant. The reasons for these dif- ferences are discussed, a genetic explanation of the susceptibility cannot be entirely ruled out.