The changing pattern of lung cancer by histological type — a review of 1151 cases from a university hospital in Japan, 1970–1989

We have analysed the frequency distribution and incidence rates for each histological type of newly diagnosed lung cancer in 1151 cases seen from 1970 through 1989 at Kyushu University, Japan. The incidence of adenocarcinoma has increased significantly since 1970. The proportion of adenocarcinoma increased from 26% to 45% in males (P<0.0001) and from 45% to 69% in females (P=0.0002). In addition, the proportion of subtypes of adenocarcinoma, classified in an electron microscopic study, underwent marked changes during the period 1982–1985; thus, e.g. 71% of all adenocarcinomas were classified as being of the bronchiolo-alveolar type. The smoking rates were similar during the period for patients with adenocarcinoma, suggesting that some etiological factors other than smoking may account for the increased incidence of adenocarcinoma. Further analysis, especially respecting dietary or ecological factors, is necessary.