Decrease in the esophageal cancer incidence rate in mountainous but not level parts of Cixian County, China, over 29 years.

Background: Cixian county has one of the highest incidence rates of esophageal cancer (EC) in China, as well as the world. In 1974, the Cixian population-based cancer registry system was established, so that there is now information on esophageal cancer cases over almost 30 years.
Methods: Data from Cixian Cancer Registry were checked and analyzed using SPSS 11.5.
Results: From 1974 to 2002, a total of 18,471 new esophageal cancer cases were registered in Cixian, 11,068 in males and 7,403 in females. The age standardized incidence rate (ASR) for males was 208.77 per 100,000, while for females it was 120.47 per 100,000. There was a clear trend for decrease overall in the incidence rate of esophageal cancer over the 29 years (X(2)=19.94, P<0.001). As to the geographic distribution, the incidence rate in mountainous and hilly areas showed a significant decline (X(2) = 195.00 and X(2) = 46.08, respectively, both P X(2)0.001). Data for esophageal cancer incidence in level land areas in contrast were relatively steadily, with increase in recent years.
Conclusion: Esophageal cancer has decreased in Cixian county during the last 29 years, but this is due to change in mountainous and hilly areas. Compared to other regions in the world, Cixian county still has a very high incidence of ECs.