The risk of radiation-induced breast cancer may outweigh the benefits of mammography in women under the age of 30 who carry a mutation in BRCA1 or BRCA2, according to a mathematical modeling study.
The general recommendation for women who carry a mutation in BRCA1/2 is to start getting annual mammograms as early as 25 to 30 years of age. However, it is not clear whether the risk of radiation-induced breast cancer would limit the benefit of early mammography.
To estimate the impact of early mammograms on overall breast cancer risk, Amy Berrington de Gonzalez, D.Phil., of the Johns Hopkins Bloomberg School of Public Health in Baltimore, and colleagues modeled excess breast cancer mortality following five annual mammograms starting at various ages.
The model indicated that women who underwent five mammograms between the ages of 24 and 29 would have an additional 26 breast cancers per 10,000 women due to the radiation. Between the ages of 30 and 34 they would have an excess of 20 additional cancers, and between 35 and 39 an additional 13 cancers. To outweigh these risks, mammography screening would have to reduce breast cancer mortality by 51 percent for women between the ages of 24 and 29, by 12 percent for those between 30 and 34, and by 4 percent for those between 30 and 34. The investigators conclude that if their assumptions are correct and mammograms reduce breast cancer mortality by 15-25 percent, which is consistent with empirical data, then there there would be no benefit for mammograms in women under the age of 30 and a marginal benefit for women between the ages of 30 and 34.
"In the absence of direct empiric data, our estimates can be used by those involved in the decision-making process for BRCA mutation carriers to assess whether the benefits from early mammographic screening are likely to outweigh the radiation risks," the authors conclude.
This research was published in the Journal of the National Cancer Institute January 27, 2009.
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