Association of adenocarcinoma of the lung with cigarette smoking by grade of differentiation and subtype.

A hospital-based case-control study was carried out in order to evaluate the risk of adenocarcinoma of the lung associated with cigarette smoking according to grade of differentiation and subtype. The cases studied were 238 patients with adenocarcinomas of the lung (158 males and 80 females) that were surgically resected at the Center for Adult Diseases, Osaka. For each case, 2 controls were chosen at the same hospital from outpatients who had not been diagnosed as having smoking-related diseases, matched by sex, age, and year of first visit. When the male cases with adenocarcinoma were classified according to the grade of differentiation, the odds ratios (ORs) associated with exsmokers and current smokers were: 1.0, 2.1 for well-differentiated; 4.1, 7.7 for moderately differentiated; and 8.5, 7.9 for poorly differentiated adenocarcinoma. The OR associated with current smokers for poorly and moderately differentiated adenocarcinoma combined was significantly higher than that for well differentiated adenocarcinoma. Approximately the same pattern of ORs was observed in females. For poorly and moderately differentiated adenocarcinoma, a significant dose-response relationship was observed in males. Comparison between the ORs for papillary type and tubular type showed no difference.