Cimetidine and gastric cancer: preliminary report from post-marketing surveillance study.

Widespread publicity has been given to te possibility that cimetidine treatment might cause gastric cancer. Preliminary data are given from a post-marketing surveillance study in four centres. A total of 9940 patients taking the drug entered study and 9504 were observed for at least a year. Seventy-four cases of gastric cancer were identified in those taking cimetidine, but 23 of these were diagnosed before the use of the drug and 29 others with advanced malignancy had received cimetidine within the previous six months only. Ten of the remaining 22 had gastric cancer diagnosed within a year of starting treatment, and 12 after more than a year; only four of the total group had histologically "early" cancer. The occurrence of gastric cancer a long time after starting cimetidine treatment cannot be explained in every case, but it is noteworthy that in control group (which is not directly comparable) gastric cancer was observed in eight patients. The hypothesis that cimetidine treatment predisposes to gastric cancer cannot be excluded by our findings: in our view, however, they do not support such an association.