The role of cigarette smoking and drinking in the development of liver cancer: 28 years of observations on male cohort members in a farming and fishing area.

: Cohort studies of 639 males in a farming area (Cohort I) and 677 males in a fishing area (Cohort II) in Kyushu, Japan, had been conducted to assess the involvement of smoking and drinking in the development of liver cancer. An observed-to-expected (O/E) ratio of liver cancer was 1.3 in Cohort I and 3.1 (p less than 0.01) in Cohort II. A significant excess in deaths was found in Cohort II. No significant risk elevation was observed for smokers and drinkers in Cohort I. Although the odds ratio (OR) of 3.6 (0.6 to 22.3) suggested an elevated risk among cigarette smokers in Cohort II, no clear linear trend of ORs was observed. In contrast, a significant elevation of OR (7.0) was noted among shochu drinkers in this cohort. The respective ORs were 5.0 (1.3 to 19.7), 8.6 (2.1 to 36.1), 14.1 (3.6 to 55.9) for shochu drinkers of less than 1, 1 to 2, and 2+ units (approximately 180 ml in volume), and a highly significant dose-response relationship was observed (chi 2 = 12.1; p less than 0.001). Multiple logistic regression analysis indicated an insignificant effect of smoking and a major contribution of drinking to the development of liver cancer. Shochu drinking (or probably high alcohol intake) seems to have a significant involvement in the etiology of liver cancer, at least in Cohort II.