Sex difference in the incidence of cardia and non-cardia gastric cancer in the United States, 1992-2014

Abstract Background Gastric cancer is more common in men than in women, but underlying reasons have not been completely understood. Methods Using data from 13 cancer registries in the Surveillance, Epidemiology, and End Results Program, we analyzed the age-specific sex difference in the incidence of gastric cancer in the United States during 1992-2014. We assessed the temporal trends in the sex differences in the incidence of gastric cancer during the study period. Results The male-to-female incidence ratio of cardia cancer increased with age until peaking at ages 55-69 years and decreased thereafter, while the ratio for non-cardia gastric cancer increased with age before ages <60 years and remained stable onwards. The age-specific patterns in the sex difference of gastric cancer incidence varied between intestinal and diffuse histological types. The sex difference in the incidence of cardia cancer remained relatively stable except for that the absolute difference between the sexes in whites decreased on average by 0.8% per year from 1992 to 2014. The absolute incidence difference between the sexes in non-cardia gastric cancer decreased over time in whites, blacks, and Asian and Pacific islanders by approximately 4% per year. The male-to-female incidence ratio of non-cardia gastric cancer decreased over time in whites and blacks, but remained relatively stable in Asian and Pacific islanders. Conclusions Both extrinsic and intrinsic factors may have contributed to the sex difference in gastric cancer. Sex hormones may play a role in the development of cardia cancer and intestinal type of gastric cancer.