Incidence and pathology of pancreatic carcinoma among atomic bomb survivors, 1950-1982

There is little evidence that pancreatic carcinoma is radiogenic in humans. To further investigate this possibility, all follow-up sources at the Radiation Effects Research Foundation were utilized to identify 378 incident cases of pancreatic cancer which occurred between October 1, 1950 and December 31, 1982 among 91,231 members of the cohort of atomic bomb survivors in Hiroshima and Nagasaki, Japan. An independent pathology review was conducted for all eligible cases, and pathology reports and slides were sought for those having a tissue diagnosis. The incidence of pancreatic carcinoma in this cohort was evaluated with respect to city, sex, age at exposure, time since exposure, radiation dose, and selected pathologic characteristics. Radiation dose effects, as well as spontaneous (background) incidence rates, were estimated using generalized Poisson regression models. Allowing for natural variations in background incidence, a significantly increased risk of pancreatic cancer was found to be associated with atomic bomb radiation exposure (relative risks = 1.3,95% confidence interval = 1.1-1.6). This relationship was much stronger in Nagasaki than Hiroshima, and among males than females. Age at exposure and time since exposure had little effect on radiation risk estimates. The interpretation of these findings in relation to their biologic plausibility is stressed, and the implications of using Radiation Effects Research Foundation incidence data in this regard are discussed