Smoking, occupation, and histopathology of lung cancer: a case-control study with the use of the third National Cancer Survey.
A case control study was designed to determine the relationship between occupation, smoking, and common histologic types of lung cancer with data collected during the Third National Cancer Survey. A total of 181,027 cancer cases were diagnosed in nine geographic areas. A random sample of 7,518 cancer cases revealed little difference between respondents and non respondents in age, race, sex, marital status, method of diagnosis, and country of birth. Under representation of cancers of the more aggressive sites (lungs, pancreas, and esophagus) and over representation of cancers with long survival times (breast, cervix, and lip) were noted. Employment history and tobacco use information were collected and coded. Only male patients 30 to 84 years of age were included in the study because of a lack of cases in females for most industrial categories. Case series were comprised of lung, bronchus, and trachea sites and divided into the three most common histologic types: squamous cell carcinoma, small cell carcinoma, and adenocarcinoma. All other cancer cases were included in the control group except for cancers associated with smoking or occupational exposures. A total of 420 respiratory cancers were in the case series. The largest histologic group of lung cancers was squamous cell carcinoma with 152 cases, followed by adenocarcinoma with 50 cases, and small cell carcinoma with 45 cases. The remaining 173 cases were either histologic types of lung cancer (37 cases) or undetermined histology (136 cases). All histologic types of lung cancer were significantly associated with higher cigarette dose categories. Small cell carcinoma displayed the strongest overall relationship, whereas the relationship to adenocarcinoma and squamous cell carcinomas had significant excesses for craftsmen and laborer categories. Laborer was the only category with significant small cell carcinoma association. The authors conclude that sensitivity epidemiologic studies can be improved by use of occupational histories and consideration of histology in examination of associations between occupation and respiratory cancers.