Risk of lung cancer by histologic type among smokers in Miyagi Prefecture.

Smoking habits of the 827 lung cancer patients aged 40 years or over who were treated in the Sendai Kosei Hospital from 1977-82 were compared with those in the general population of a non-metropolitan district in northern Japan, which we recently surveyed by mail questionnaire. The relative risks of lung cancer by histologic type adjusted by age and area of residence were as follows: 1.9 for adenocarcinoma, 4.3 for squamous cell carcinoma, 3.9 for small cell carcinoma and 3.4 for large cell carcinoma in men, and 2.9, 6.4, 4.5 and 4.0 for these histologic types, respectively, in women. These elevated risks were all statistically significant (p less than 0.05). These findings suggest that smoking habits should be carefully considered when studying the etiology of any cell type of lung cancer, even adenocarcinoma, which often has been thought to be unrelated to smoking habits.