[A study of the incidental rate of the radiation-induced cancer in the head and neck region].

In a review of 2710 patients with head and neck disease treated with irradiation at the Cancer Institute Hospital, Tokyo, between 1946 and 1955, second primary malignancies occurred in 35 of 2223 patients who were treated by reason of malignant tumors. The incidental rate of these second primary malignancies was significantly different from the population based rates. In 10 of 292 patients who were treated by irradiation for reason of benign disease such as cervical tuberculosis and hemangioma, primary cancers were developed under the long period of observation. These primary cancers were proved to be radiation-induced malignancies.