Smoking habits and carcinoma of the stomach: a case-control study.

Over a period of 8 years, a case-control study was carried out on smoking habits in 117 patients with carcinoma of the stomach and 234 controls, and a significant association of a particular method of smoking with the site of gastric carcinoma was found in the cancer patients. Furthermore, there was a highly significant difference in method of smoking between the cancer patients and the control group. The prevalence of smoking habit in the latter was 37%, of which 26% had swallowed the smoke regularly. In contrast, the incidence of smoking habit in the cancer patients was over 56%, of which 64% had swallowed the tobacco smoke. The difference is highly significant (P less than 0.001). The study also suggests that the distal part, in particular, the antrum of the stomach was affected more frequently among the smokers of the cancer patients who had swallowed the smoke regularly but the cardiac end seemed to be involved more often in the other groups of the cancer patients. These included 'never-smokers,' ex-smokers and those smokers who did not swallow the smoke (P less than 0.01). It is therefore concluded that the swallowing of tobacco smoke seems to influence the site of gastric carcinoma. The relative risk was six-fold higher among the smokers who did swallow the smoke compared with the 'never-smokers' of the control group.