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BREAST-CANCER RISK FROM RADIATION IS MINIMAL AFTER AGE 35.

Studies have shown that exposure to high-dose radiation increases the risk of breast cancer. Quantifying the risk from low-dose radiation (as from mammography or chest x-rays) has been difficult, forcing researchers to extrapolate from data on high-dose exposure. These investigators studied a cohort of 31,710 women, of whom more than 8000 were exposed to repeated, relatively high doses of radiation during fluoroscopic examinations between 1930 and 1952.

As expected, radiation exposure was associated with a higher relative risk of breast cancer, and the data conformed to a linear dose-response model. Cancers were most likely to appear 25 to 34 years after the first exposure.

Most important, the risk of breast cancer was greatest in women first exposed between ages 10 and 14; thereafter, the risk dropped sharply. Women first exposed after age 35 -- when most women begin to have mammograms -- had a much lower excess risk, leading the authors to conclude that the risk of breast cancer from contemporary mammography is probably outweighed by the benefits of finding early breast cancer.

— ALK

Published in Journal Watch General Medicine November 17, 1989

Citation(s):

Miller AB et al. Mortality from breast cancer after irradiation during fluoroscopic examinations in patients being treated for tuberculosis. N Engl J Med 1989 Nov 9 321 1285-1289.

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