Skin and Neck Cancer following Radiation Therapy for Benign Diseases.

Sixty-one cases of radiation-induced cancer were collected from selected big hospitals in Japan during 1961 and 1962. Of 61, 54 were cancer of skin or neck including the thyroid gland. All these cancers were developed in the area previously irradiated for treatment of benign diseases over throe years ago. The rate of male to female was approximately the same as that of natural cancers. Radiation-induced cancer tended to occur more frequently in younger ages than natural cancers particularly in thyroid cancer. The latent period was dis tributed between 3 and 47 years with an average of 19.8 years. The frequency distribution of the latent period showed nearly the logarithmic normal curve. The latent period tended to increase with a decrease of radiation dose. About a half of original diseases previously irradiated for was tuberculous cervical lymphadenitis. Thyroid adenoma and various skin diseases were followed in this order.