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January 30, 2009 — The current recommendation is that women with BRCAmutations, who are thus at high risk for breast cancer, start receiving annual screening mammography as early as age 25.
However, a new risk-analysis study published online January 27 in the Journal of the National Cancer Institute suggests that screening should probably not start until age 35.
The study estimates that, for BRCA-mutation carriers 25 to 34 years, the risk of developing breast cancer from cumulative radiation exposure outweighs or neutralizes the benefit of the mortality reduction from the early screening.
"Exposure to ionizing radiation from repeated diagnostic x-rays is an established cause of breast cancer," write Amy Berrington de Gonzalez, DPhil, from the Johns Hopkins Bloomberg School of Public Health, in Baltimore, Maryland, and her coauthors. Nonetheless, the safety and efficacy of mammographic screening before age 40 in BRCA-mutation carriers has not been demonstrated directly, they add.
The study is the first of its kind in BRCA-mutation carriers. The investigators had previously compared the benefit from mammographic screening before the age of 40 with the radiation risk for women with a family history of breast cancer.
No Substantial Net Benefit Until Age 35
To estimate the impact of early mammograms on overall breast cancer risk, the investigators mathematically modeled excess breast cancer mortality after 5 annual mammograms starting at various ages.
The model indicated that women who underwent 5 mammograms between the ages of 24 and 29 years would have an additional 26 breast cancers per 10,000 women because of radiation exposure.
Between the ages of 30 and 34 they would have 20 additional cancers, and between 35 and 39 they would have 13 additional cancers.
"The lifetime risk of radiation-induced breast cancer will be higher for women who start [annual] mammography at younger ages because of the longer time available to accumulate risk," explain the authors.
Natl Cancer Inst. 2009;101:205-209.