Cutaneous carcinomas and soft tissue sarcomas induced by ionizing radiation therapy. Presentation of a series of 42 cases.

Forty-two cases of tumors of the skin and of the soft tissues immediately beneath the skin, presumably induced by ionizing radiotherapy, are reported: 35 were carcinomas, 2 angiosarcomas, 2 leiomyosarcomas of the dermis and 3 fibrosarcomas. In 31 of the 35 cases of carcinomas, multiple neoplastic foci were found in the skin area exposed to the ionizing radiation. The median age of the patients at the time of exposure to ionizing radiation was 32.5 years for those with carcinomas and 30 years for the others. The relatively young age at exposure to the ionizing radiation may have influenced onset of the tumor. The median interval between exposure to ionizing radiation and clinical finding of the tumor was 18.1 years for the carcinomas and 16 for the other tumor types. The radiation dose to which the patients had been subjected varied for the carcinomas from 12 to 25 Gy and for the other tumors from 40 to 50 Gy, administered over 1 to 4 years in the cases of carcinomas and 4 to 5 weeks in the other cases. The dose administered to the cases with cutaneous carcinomas was rather low, since almost all these patients had benign disease; however, it is in this dose range (12-25 Gy) that, according to Gray, a relatively high incidence of induced tumors is verified. In the opinion of the author of the present paper, the multiplicity of neoplastic carcinomatous foci in the skin area exposed to radiation confirms Gray's hypothesis; also, the time over which the dose was administered was presumably important in determining such multiplicity. The soft tissue sarcomas occurred only in patients previously subjected to radiotherapy, according to traditional modalities, for malignant neoplasms. The carcinomas were observed almost always in the trunk, and like spontaneous carcinomas at this site they were almost exclusively of basal cell type.