Smoking, occupation, and histopathology of lung cancer: a case-control study with the use of the Third National Cancer Survey.

The relationships between occupation, smoking, and the three most common histologic types of lung cancer (squamous cell carcinoma, small-cell carcinoma, and adenocarcinoma) were explored in a case-control study with the use of data collected during the Third National Cancer Survey. The largest histologic group was squamous cell carcinoma (152 cases), followed by adenocarcinoma (50 cases), and small-cell carcinoma (45 cases). The control series was comprised of cancers at all anatomic sites except those believed to be associated with either smoking or occupational exposures. Cigarette smoking was significantly associated with all three histologic types of lung cancer. Overall, the relationship with small-cell carcinoma was strongest (odds ratio = 5.1), whereas those with squamous and adenocarcinoma were approximately equivalent (odds ratio = 3.1). Dose-response relationships were evident for all three histologic types; however, the linear relationship was found to be statistically significant (P less than 0.05) only for squamous and small-cell carcinomas. Squamous cell carcinoma was the type most frequently associated with occupational categories. It was significantly associated (P less than 0.05) with "blue collar" professions (odds ratio = 2.1). No occupational categories were significantly associated with adenocarcinoma. In addition, no occupational categories were associated with all histologic types of lung cancer combined. This last observation suggested that the sensitivity of epidemiologic studies might not only be increased by use of improved occupational histories but more specifically by consideration of histology in examination of associations between occupation and respiratory cancer.