Occupation and lung cancer risk. An analysis by histologic subtypes.

The relationships between cigarette smoking, occupational exposures, dietary vitamin A and lung cancer is explored in a case-control study. The study is based on 1002 primary lung cancers among white men and 1119 white male controls between 35 and 79 years of age admitted to Roswell Park Memorial Institute from 1957 to 1965. Four hundred sixty-four lung cancer cases were classified as one of the three major histologic cell types: squamous, small cell, or adenocarcinoma. Each of the three main histologic types displayed a statistically significant trend of increasing risk associated with increasing consumption of cigarettes with the strongest relationship being seen for small cell carcinoma (odds ratio for 40+ pack-years = 17.5) and the weakest with adenocarcinoma (odds ratio for 40+ pack-years = 6.7). Increasing risk for squamous cell cancer was seen with increasing duration of exposure to all lung carcinogens, asbestos, and aromatic hydrocarbons. Small cell carcinomas were not associated with any of the occupational exposure categories studied with the exception of asbestos exposure in light smokers. Increasing risk of adenocarcinoma was seen with increasing duration of employment in occupations with potential exposure, but only for light smokers. Dietary vitamin A consumption did not confound the occupational associations. Hypotheses have been generated regarding interplay of risk factors in the etiology of different histologic subtypes of lung cancer. Studies of specific histologic types of lung cancer are needed to elucidate the role of various environmental and occupational risk factors.