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The recently increasing trend of lung cancer mortality in Japan was qualitatively analyzed. As the percentages of cases undergoing pathological autopsies in Tokyo were thirty for males and twenty-six for females during the period from 1979 to 1983, the histologically classified death rates in Tokyo could be estimated by combining the reported cases of death from lung cancer with the proportion of these of known histological type. The results indicated an increase in adenocarcinoma, and a decrease in squamous-cell carcinoma, except for the older age-group of men. The latter result suggested that the results were affected by the decreasing proportion of smokers and by the improvement in cigarette quality. The increase in small-cell and large-cell carcinoma, and the decrease in undifferentiated carcinomas, could be explained by problems associated with differing diagnostic standards. However, when these three different types of carcinoma were considered as a single type, the death rate was shown to be increased except in younger age-groups of women.

Multiple primary cancers in 30,386 consecutive autopsy cases from 1883 to 1982 in Tokyo University Hospital and 273,796 registered autopsy cases from 1974 to 1982 in Japan were examined. The frequency of multiple primary cancers among all cancers at Tokyo University Hospital was less than 0.5% until 1940. From 1960, it gradually increased, reaching 6.9% (1970-1982). The average age of patients with a single cancer was around 45 years until 1960. Thereafter, it became high, averaging 54.2 years in 1970-1982. The average age of patients with two and three or more primaries in 1970-1982 was 62.1 and 68.5, respectively. As the autopsy rate of cancers in Japan is 11.1% in 1974-1982, the statistics from the Autopsy Registry are highly representative of those in Japan. The frequency of multiple primaries was 5.5% in the Registry and increased year by year (3.6% in 1974 to 7.1% in 1982). The average age of patients with one, two and three or more primaries was 58.9, 66.7 and 69.8. In these two series, the older the patients, the larger was the number of primaries. In multiple cancers, the frequent combination consisted of the stomach, lung, colon, liver, prostate and thyroid. The stomach, lung, colon and liver were frequent primary sites when they occurred singly. The thyroid and prostate were frequent primary sites found at autopsy. Senescence of the Japanese population is suggested as one of the factors for an increase of multiple primaries in the last 20 years.