Trend of lung cancers in the National Cancer Center of Japan and comparison with that of Japanese pathological autopsy records

Abstract

Trends in the histologic types of lung cancers during 1966-1985 by 5-year intervals were analyzed by using 4,419 cases in the National Cancer Center Hospital, Japan. Histologically confirmed cases increased to 76.6% in the last 5-year interval. The proportions of histological types in males have remained relatively unchanged; about 40% squamous cell carcinoma, one-third adenocarcinoma, and about 10% each of large cell carcinoma, small cell carcinoma and other types. In females, an increase of adenocarcinoma from 52% to 69.1% and a decrease of squamous cell carcinoma from 21% to 11.4% were noteworthy, and the other three types amounted to less than 10% each. These trends were compared with those obtained from the Annals of Pathological Autopsy Records in Japan during 1974-1983, which contained 26,844 lung cancer cases; the results were similar except for an increase of small cell carcinoma. The recent increase of small cell carcinoma was considered to be due to a change in diagnostic categorization, associated with a decreased rate of undifferentiated carcinoma. However, the increase of small cell carcinoma as well as adenocarcinoma in younger patients requires further study from both demographic and etiological viewpoints.