Effects of radiation on incidence of primary liver cancer among atomic bomb survivors

We describe the radiation risk for primary liver cancers between 1958 and 1 987 in a cohort of atomic bomb survivors in Hiroshima and Nagasaki, Japan. The analysis Is based on a comprehensive pathology review of known or suspe cted liver neoplasms that generated 518 incident, first primary cases, most ly hepatocellular carcinoma, Excess relative risk from atomic bomb radiatio n was linear: 0.81 per sievert weighted liver dose (95% CI [0.32, 1.43]; P < 0.001). Males and females had similar relative risk so that, given a thre efold higher background incidence in males, the radiation-related excess in cidence was substantially higher in males. Excess risk peaked for those wit h age at exposure in the early 20s; there was essentially no excess risk in those exposed before age 10 or after age 45. Whether this was due to a dif ference in sensitivity or possible confounding by other factors could not b e addressed retrospectively in the full cohort. A paucity of cholangiocarci noma and hemangiosarcoma cases suggested that they are not significantly as sociated with whole-body radiation exposure, as they are with the internal or-particle-emitting radiological contrast medium Thorotrast, Because most of the radiation-related excess eases occurred among males, it is important to ascertain what factors put men at greater risk of radiation-related liv er cancer. (C) 1999 by Radiation Research Society.