Cancer incidence in old age.

The incidence of all cancer increases with age through most of the human life span, but its real incidence at very old ages has not been well elucidated to date. Clarification of the real incidence of cancer in old age, especially among centenarians, may well provide pivotal information to understand the characteristics of humankind. In this study, autopsy records of the Annual of the Pathological Autopsy Cases in Japan, 1991-1996, vols. 34-39 (Japanese Society of Pathology, Tokyo) were used. Cases over 90 years old were studied individually for accurate analysis. The incidence of cancer peaked in the 6th decade and that of multiple cases in the 8th decade. In groups over 90 years of age, the incidence at 5-year intervals did not show any significant decrement. Moreover, the metastatic rate and rate of death due to cancer among centenarians was about three-fourths and two-thirds, respectively, of that of cases aged 90-94 years. The decrease in the metastatic ratio and less mortality due to cancer occurring at the oldest ages are considered due to the nature of cancer itself. The fact that the incidence of cancer does not increase would suggest that certain people among those of advanced age have a special resistance to it.