A statistical analysis of lung cancer registered in the Annual of Pathological Autopsy Cases in Japan between 1958 and 1987, with special reference to the characteristics of lung cancer in Japan.

Autopsy cases of lung cancer, 41,988 in males and 13,818 in females, consecutively registered between 1958 and 1987, were analysed statistically and compared with other case materials and mortality statistics. Cases of malignant tumor showed a gradual increase, and now comprise 60% of the total male and 55% of the total female autopsy cases. The percentage of lung cancer cases among the total autopsy cases was 9% for males and 5% for females. The percentage of lung cancer cases among total cases of malignant tumor was about 17% for males and 9% for females. Among fatal malignant tumors, gastric cancer and lung cancer showed the highest frequency. The relative incidence of gastric cancer was seen to decrease, whereas that of lung cancer increased. Of the histological types of lung cancer in both sexes, adenocarcinoma was the most frequent, followed by squamous cell carcinoma. During the period studied the peak age of patients with lung cancer shifted from the seventh to eighth decade, and a significant elevation of mean age was demonstrated for all of the major histological types in both sexes. The male:female ratio for all lung cancer cases was 3.0, which was much lower than those for the United States and Europe, but very similar to the ratios of mortality statistics in Japan and other Asian countries. As a result of a previous autopsy study at the University of Tokyo, it was also confirmed that the male:female ratio relative to age in each country reflects very well the histological distribution.