Multiple fluoroscopy of the chest: carcinogenicity for the female breast and implications for breast cancer screening programs.

The risk of radiation carcinogenesis has been established for breast tissue from experience with total body irradiation and multiple fluoroscopy of the chest with the patient prone. The doubling dose has been estimated to lie between 20 and 50 rads. Before undertaking radiologic screening programs for breast cancer, therefore, it is necessary to determine whether exposures below this range are safe. Of 792 women who had had tuberculosis and were followed for a minimum of 20 years, 451 had had multiple fluoroscopy while supine; 341 had not had fluoroscopy. The first group received a total radiation dose to the breast averaging 17 rads (141.5 fluoroscopies); the incidence of breast cancer in this group was not increased. Had fluoroscopy been performed with the patient prone the total radiation dose would have averaged 308 rads. The difference is thought to explain the increased incidence of breast cancer attributable to fluoroscopy given with the patient prone. Mid-breast exposure with mammography or xeroradiography varies between 3 and 6 rads. Repetitive screening would, therefore, appear safe provided total exposure did not exceed 20 rads. With this restriction there would appear to be no reason to curtail screening of women for breast cancer.