PREVALENCE RATE OF THYROID-DISEASES AMONG AUTOPSY CASES OF THE ATOMIC-BOMB SURVIVORS IN HIROSHIMA, 1951-1985

To examine the radiogenic risk of latent thyroid cancer, thyroid adeno ma, colloid/adenomatous goiter and chronic thyroiditis, the data for 3 821 subjects collected in the course of autopsies of atomic bomb survi vors in Hiroshima from 1951 to 1985 by the Radiation Effects Research Foundation (RERF) were analyzed using a logistic model. About 80% of t he autopsies were performed at RERF and the remainder at local hospita ls. The frequencies of the above diseases were not associated with whe ther the underlying cause of death was cancer. However, note that our results may be influenced by potentially biasing factors associated wi th autopsy selection. The relative frequency of latent thyroid cancer (greatest dimension less than or equal to 1.5 cm but detectable on a r outine microscopic slide of the thyroid gland) increased as the radiat ion dose increased and was about 1.4-fold greater at 1 Gy than in the O-Gy dose group. The relative occurrence of thyroid adenoma also incre ased as radiation dose increased, and was about 1.5-fold greater at 1 Gy than in the O-Gy dose group. Sex, age at the time of the bombing or period of observation did not significantly modify the radiogenic ris ks for thyroid adenoma or latent thyroid cancer. No statistically sign ificant association was found between radiation exposure and the rates of colloid/adenomatous goiter and chronic thyroiditis. The possible l ate effect of atomic bomb radiation on the frequency of benign thyroid diseases is discussed on the basis of these data. (C) 1995 by Radiati on Research Society