Esophageal and gastric carcinoma in Norway 1958-1992: incidence time trend variability according to morphological subtypes and organ subsites.

The occurrence of adenocarcinoma (AC) of the esophagus and gastric cardia has shown large increases in many but not all examined populations. This trend is in contrast with a decrease in distal gastric AC and a relative stability of esophageal squamous cell carcinoma. Our study aimed to describe esophageal and gastric carcinoma time trends in the Norwegian population between 1958 and 1992 based on data from the Cancer Registry of Norway. Estimated esophageal AC rates have accelerated over the study period, reaching average annual increases of 17% in men and 14% in women between 1983 and 1992. The occurrence of esophageal squamous cell carcinoma was relatively stable in both sexes. Proximal gastric cancer rates were stable in males and decreased somewhat in females. Distal gastric tumors showed decreases in both sexes, but were more pronounced in females. The strong increase in esophageal AC incidence parallels similar increases in the United States and some other countries. Although the observed increase may be explained to some extent by a shift in the classification of esophago-cardial adenocarcinomas, the figures are compatible with a real increase. AC of the esophagus, the proximal stomach and the distal stomach exhibit different epidemiological features, both in terms of sex ratios and time trends, suggesting risk factor differences between the subsites.