Radiation-induced cancer as a factor in clinical decision making (the 1989 ASTRO Gold Medal address)

1. Ionizing radiations are weak carcinogens. Under certain conditions they can induce cancers in experimental animals and humans. 2. This potential carcinogenicity has been a deterrent to the use of radiation therapy despite its many advantages in the management of patients with cancers. 3. In a range of clinical situations, such as the irradiation of cancers arising in the head and neck, breast, prostate and skin, an increase of second cancers can not be detected above the natural frequency of additional cancers. In the curative treatment of patients with Hodgkins disease, ionizing radiations are not associated with an increased frequency of leukemias and induced second tumors are no more frequent than following the use of alkylating agents. 4. All second tumors attributed to radiation therapy occur after a latent period of many years and except for leukemia usually are potentially curable. 5. The risks of radiation-induced second cancers are no greater than the risks of operative or anesthetic deaths and these catastrophes are immediate and non-remedial. 6. Therefore, at this time, the potential of radiation-induced cancers should not be a factor in the selection of treatment for patients with cancer.