RISK OF CANCER AMONG ATOMIC-BOMB SURVIVORS

This report describes the risk of cancer and in particular cancers other than leukemia among the survivors of the atomic bombing of Hiroshima and Nagasaki. Attention focuses primarily on the risk of death from cancer among individuals in the Life Span Study sample of the Radiation Effect Research Foundation in the period 1950-1985 based on the recently revised dosimetry, termed the DS86 doses. Mortality from malignant tumors is increased among A-bomb survivors as a late effect of A-bomb radiation. Besides the well-known increase of leukemia, there also has been demonstrated increase of cancer of the lung, breast, esophagus, stomach, colon, ovary, urinary bladder, thyroid, and of multiple myeloma, but no increase has yet been observed in mortality from cancer of the rectum, gallbladder, pancreas, prostate and uterus, and of malignant lymphoma. The pattern of appearance over time of radiation-induced cancer other than leukemia differs from that of leukemia. In general, radiation-induced solid cancer begins to appear after attaining the age at which the cancer is normally prone to develop (so-called cancer age), and continues to increase proportionately with the increase in mortality of the control group as it ages. Sensitivity to radiation, in terms of cancer induction, is higher for persons who were young at the time of the bomb (ATB) in general than for those who were older ATB. Furthermore, susceptibility to radiation-induced cancer tends to be higher in pre- than in post-natally exposed survivors (at least those exposed as adults). Other radiation effect modifiers and the shape of the dose response curve will also be discussed.