BACKGROUND: Previous studies of Japanese patients showed that distal gastric carcinomas (of the corpus or the antrum) were associated with histologic changes in the non-neoplastic gastric mucosa. These changes (cells with ciliated metaplasia, with large and small mucus-negative vacuoles, intramucosal glandular cysts, and extensive intestinal metaplasia) were often found in carcinomas of intestinal type.METHODS: In the present work, similar mucosal changes were searched for in surgical specimens carrying a carcinoma of the cardia. A total of 12 079 archival histologic sections, corresponding to 563 gastrectomies performed in Japanese patients, were analyzed.RESULTS: Of the specimens with cardia carcinoma of intestinal type seen in Tokyo ( n = 169) and in Matsuyama ( n = 168), 53.3% and 63.1% contained intramucosal cysts; 39.6% and 51.8%, ciliated metaplastic cells; 34.9% and 30.4%, large vacuolated cells; and 7.7% and 11.9%, small vacuolated cells; and 69.8% and 68.5% had high intestinal metaplasia scores, respectively. These percentages were significantly higher than those for cardia carcinomas of diffuse type in Tokyo ( n = 153) and in Matsuyama ( n = 73), in which 30.7% and 34.2% of the specimens had intramucosal cysts; 17.6% and 17.8%, ciliated metaplastic cells; 14.4% and 9.6%, large vacuolated cells; and 3.9% and 4.1%, small vacuolated cells; and 43.1% and 39.7% had high intestinal metaplasia scores, respectively.CONCLUSION: Thus, similarly to carcinomas of the corpus or the antrum, cardia carcinomas of intestinal type are associated with histologic changes in the gastric mucosa. The possibility that these changes are evoked by environmental factors was entertained.