The high incidence of esophageal cancer in parts of China may result primarily from genetic rather than environmental factors

About 40,000 inhabitants migrated from a high-risk area of esophageal squamous cell carcinoma (ESCC) to a low-risk area of esophageal cancer 40 years ago. Little is known about the change in the mortality in esophageal cancer among these immigrants. This study examined the impact of changing environments on esophageal cancer by comparing age-standardized mortality rates of immigrant group to the rates of native population (natives who live in high cancer location and have never moved) and host populations (hosts who live in low cancer location and have never moved people). All ESCC deaths taking place during 1999-2004 among the migrant, native, and host populations were identified by retrospective population-based screening. Direct age-adjusted mortality rates were calculated by using the China population of year 2000 as standard population. From 1999-2004, the average annual age-adjusted mortality of ESCC for the migrant, native, and host population was 61.6/100,000, 59.7/100,000, and 6.7/100,000, respectively. No decreasing tendency was found in mortality rate of ESCC in the population of young immigrants. The mortality rate of ESCC of migrants remained high even they had been living in the low endemic region for 40 years. This study strongly suggested that genetic susceptibility, rather than environment exposure, is responsible for the high risk of ESCC in the migrants.