An epidemiologic study on carcinoma of the breast following irradiation for benign conditions in infancy and childhood

To investigate the relationship of irradiation during infancy and childhood to the subsequent development of carcinoma of the breast, 996 eligible patients were studied at Evanston Hospital, Evanston, Illinois, and Northwestern Memorial Hospital, Chicago. This was a case-control study, with those in the control group being selected from concurrent hospital admissions for nonmalignant surgical conditions. A second group consisting of those with benign biopsy results was also studied. The Mantel-Haenszel method of analysis, controlling for age and race, was used to estimate the approximate relative risk of carcinoma of the breast in the irradiated group compared with that for the nonirradiated group The type of radiation history included radiotherapy for mastitis or enlarged thymus (nine patients), irradiation of the head and neck (69 patients), diagnostic fluoroscopies (ten patients) and miscellaneous irradiation (52 patients) for bursitis, eczema or keloid. Based upon the data obtained from the results of this study and its analysis, we conclude that there is little evidence of increased risk of carcinoma of the breast after irradiation about the head, neck and chest areas for benign conditions in the population being studied herein. Such a risk, if indeed it exists at all for this population, is estimated to be about 10 per cent.