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.