Cohort Analysis of Death from Malignant Neoplasms in Japan

(1) Cohort analyses were made of the total and partial death rate for malignant neoplasms in both sexes. (2) The cohort phenomenon was shown in the transition of the total death rate induced by malignant neoplasms in both sexes. The age-specific death rate curve forms a line similar to the rectilinear pattern seen in the middle age groups and above. (3) Decreasing cohort phenomena were seen in the uterine and stomach cancer analyses. Both forms of cancer are now on the decrease. (4) Increasing cohort phenomena were demonstrated in the lung and pancreas cancer analyses for both sexes. The rate of increase has nearly reached zero, and the age-specific death rate curves are approximately straight lines. (5) A two-phase cohort phenomenon was observed in the liver cancer analysis for females. (6) The transition of the death rate for leukemia showed cohort phenomena for both sexes. However, a final age-specific death rate curve is being reached, and the nature of this disease has changed. (7) The transition of the death rates for malignant neoplasms according to site can be classified as with and without cohort phenomena. Those that showed cohort phenomena can be classified into four types. a) The simple decreasing cohort phenomenon b) The two-phase cohort phenomenon c) The increasing cohort phenomenon that produces an age-specific death rate curve with a rectilinear pattern. d) The increasing cohort phenomenon in all age groups. (8) Suggestions for health control and related etiology were made in relation to the cohort phenomenon shown in malignant neoplasms.