||BACKGROUND: Using data from the U.S. National Cancer Institute's Surveillance, Epidemiology, and End Results program, we analyzed stomach carcinoma incidence patterns by both histologic type and anatomic site. METHODS: We calculated age-adjusted (2000 U.S. standard) rates for 1978 to 2005, and for five time periods from 1978-1983 through 2001-2005 according to histologic type and anatomic site, separately and jointly. We also analyzed rates by race, gender, and age group. RESULTS: During 1978 to 2005, more than 54,000 stomach carcinoma cases were diagnosed among residents of the nine Surveillance, Epidemiology, and End Results areas. Total stomach carcinoma rates declined by 34% from the 1978-1983 to the 2001-2005 time periods. By histologic type, intestinal rates decreased consistently, whereas those for diffuse rates increased through 2000 and declined in recent years. By anatomic site, cardia rates increased during earlier years and then decreased, whereas rates for all other sites declined. When considered jointly by histologic type and anatomic site, intestinal carcinoma rates decreased for all sites except the cardia; diffuse rates increased through 2000 and decreased in recent years for all sites except the overlapping/nonspecified sites. Both diffuse and intestinal rates were lowest among whites, intermediate among blacks, and highest among the other, primarily Asian, races, with only modest gender differences for the diffuse type. In contrast, cardia carcinoma rates were highest among whites and were notably higher among males, especially whites among whom the male/female rate ratio was five to one. CONCLUSIONS: Stomach carcinoma incidence patterns differ by histologic type, anatomic site, race, gender, and age, suggesting that etiologic heterogeneity should be pursued in future research.