SKIN TUMOR RISK AMONG ATOMIC-BOMB SURVIVORS IN JAPAN

Objectives: Elevated risks of skin cancer following high doses of ioni zing radiation have long been known, Recent reports on atomic-bomb sur vivors indicate that nonmelanoma skin cancer can be induced at low to medium doses, We studied atomic-bomb survivors to determine the effect s of radiation on specific histologic types of skin cancer and to desc ribe the dose-response relationship. Methods: Cases of melanoma, nonme lanoma skin cancers, and Bowen's disease were ascertained between 1958 and 1987 for the 80,000 cohort members through the population-based H iroshima and Nagasaki (Japan) tumor registries augmented by searches o f other records. Results: An excess of basal cell carcinoma (n = 80), with some suggestion of a non-linear dose-response, was observed. The excess risk decreased markedly as age at exposure increased, and there was no evidence for an interaction between ionizing and ultraviolet r adiation. No dose-response was found for squamous cell carcinoma (n = 69), The excess relative risk point-estimates were large, but statisti cally nonsignificant for both melanoma (n = 10) and Bowen's disease (n = 26). Conclusions: The basal layer of the epidermis appears to be qu ite sensitive to radiation carcinogenesis, particularly at a young age , The suprabasal layer seems to be more resistant, as shown by the lac k of an association for squamous cell carcinomas.