Clinicopathological study of gastric carcinoma in high- and low-mortality countries: Comparison between Japan and the United States.

BACKGROUND: Gastric carcinoma is a tumor that shows marked differences in geographic distributions. The incidence of the gastric carcinoma has been falling dramatically in Western countries. In sharp contrast, the incidence in Japan is still quite high.METHODS: A comparative clinicopathological study was performed, examining gastric carcinomas in 978 Japanese patients (Tokyo) and 157 United States patients (San Diego), that had been surgically resected over the 11-year period 1980-1991.RESULTS: The median age of US the patients (64.1 years) was higher than that of the Japanese patients (59.0 years). There was no difference in the sex ratios. Forty-five of the Japanese patients had early gastric cancer, while this occurred in 10% of the US patients. In terms of tumor location, 47% were in the upper portion of the stomach in the US patients, while, in contrast, this proportion in Japanese patients was 23%. In association with the marked difference in tumor location, 36.5% of the US patients underwent operations with the thoraco-abdominal approach, while this approach was used in 7.5% of the Japanese patients. The distribution of histological types was similar in the two countries' samples. There was also no significant difference in the distribution of the histological types in the same age groups in the two countries' samples. The rate of the well differentiated type increased with age while the rate of poorly differentiated type decreased. In US patients, 35.8% had marked neural invasion, while this occurred in 8.5% of Japanese patients.CONCLUSION: This study revealed marked differences in the features of gastric cancer between the US and Japan in terms of tumor location and surgical procedures.