Marked regional variation in adenocarcinomas of the esophagus and the gastric cardia in the United States.

BACKGROUND: Adenocarcinomas of the esophagus and the gastric cardia recently have experienced rapidly increasing incidence rates. Although these sites frequently are combined, they may have different risk factors.

METHODS: The authors compared regional incidence rates of esophageal adenocarcinoma, gastric cardia adenocarcinoma, and esophageal squamous cell carcinoma within the U.S. Surveillance, Epidemiology, and End Results (SEER) cancer registry for the years 1973-1998.

RESULTS: Regional incidence rates varied considerably. The Seattle-Puget Sound registry's recent average esophageal adenocarcinoma rates were over twice as high as those of the Utah registry (5.3 vs. 2.4 per 100,000 persons per year; P < 0.01); gastric cardia rates also differed (4.0 vs. 2.8 per 100,000 persons per year; P < 0.01). The incidence rate increase also varied markedly between regions. Since 1974, white male esophageal adenocarcinoma rates increased by 800% in Seattle compared with an increase of only 300% in Utah. In contrast, white male cardia adenocarcinoma rates increased by only 16% in Seattle (from 3.1 per 100,000 persons per year in 1974 to 3.6 per 100,000 persons per year in 1998) compared with 300% in Utah (from 0.7 to 2.2 per 100,000 persons per year). Both types of adenocarcinoma were more common in males and in the white population in all regions, but recent esophageal adenocarcinoma rates for black males in Connecticut were significantly higher than the U.S. black male average (3.1 vs. 0.8 per 100,000 persons per year; P < 0.01) and equaled the rates for the white population in some areas. Esophageal adenocarcinoma rates continued rising for white males through 1998, whereas cardia adenocarcinoma rates stabilized after 1988.

CONCLUSIONS: There are substantial regional, temporal, and ethnic differences between esophageal adenocarcinoma incidence rates and gastric cardia adenocarcinoma incidence rates within a single cancer registry system. Thus, these malignancies may differ in important ways and should not be combined routinely in research studies. Individual-level studies are needed to explain these substantial regional and ethnic differences.