Malignancies developed in the previously irradiated area, 3

Twelve cases with radiation-induced cancer who had previously been irradiated for malignancies are reported. There were four cases of the maxillary sinus, three cases of the larynx, three cases of the pharynx and one case each of the gingiva and the external ear. All of the cases were squamous cell carcinomas; 9 of the 12 cases occurred in males. In 10 of the 12 cases, the primary malignancies for which the irradiation was given were cancer of the larynx and of the maxillary sinus. The mean age at the time when these patients were first subjected to radiation therapy was 49 years, which was lower than that of the patients with naturally occurring head and neck cancers where the range was from age 56 to age 60. The mean age at the time when the secondary cancers were confirmed was 63 years, with a range from age 41 to age 81. Consequently, the patients irradiated for malignancies had short latent periods with an average of 13.5 years for the development of the secondary cancers, as compared with the patients irradiated for benign diseases where the average was 21 years. The dose of radiation in the site of the secondary cancers was between 4,000 and 7,000 rad in most cases. There was no close correlation between the latent period and the radiation dose. (author)