X-RAY-INDUCED SKIN CANCER IN MAN

Abstract

Development of cancer in human skin exposed to ionizing radiation is considered in terms of cell type of the observed tumors, relation between dose and effect, and mechanism of carcinogenesis. Human skin exposed to ionizing radiation may develop squamous-cell and basalcell carcinoma, occasionally sarcoma, and perhaps rarely, malignant melanoma and sebaceous carcinoma. The dose range required for radiation carcinogenesis in man is not precisely known. While a definite threshold dose cannot be demonstrated, it appears that carcinoma does not commonly develop in the absence of late sequelae. In most cases, skin cancer develops from chronic lesions resulting from repeated irradiation giving high total doses. These changes are not usually produced with total doses below 100 r. The upper limit of the carcinogenic range seems to be below the dose level used for cancer therapy. The mechanism of the genesis of radiation-induced carcinoma appears to be exceedingly complex. However, a considerable body of evidence suggests that perhaps at least two general tissue responses are involved, direct and indirect. These direct and indirect mechanisms operate in the production of radiation-induced cancer of the human skin; there is a possibility that in addition to radiation, other factors, as yet undefined, may exert amore » synergistic or cocarcinogenic effect. (H.H.D.)« less