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Health benefits, risks weighed for mammography in 40-something women

December 08, 2006

Conducting routine screening mammograms for women in their 40s is appropriate when the women and their doctors consider the benefits and the risks, according to a University of Rochester Medical Center breast oncologist.

In the Dec. 9 issue of The Lancet, Gary Lyman, M.D., M.P.H., co-authored a report with Benjamin Djulbegovic, M.D., from the H. Lee Moffitt Cancer Center & Research Institute at the University of South Florida, addressing this controversial issue of mammography in younger women. The commentary was published in the journal to accompany a report of results of a clinical study of 160,000 women screened in their 40s compared to women who underwent mammography in their 50s. Lyman and Djulbegovic assessed this study and nine others published on the subject.

Doctors have long recommended routine screening mammography for women 50 and older. However, there has been much debate about whether the annual screening is necessary and safe for women under 50. The report cites the lack of reliable data that assesses the benefits and risks of screening for women ages 40 to 49.

"Evidence shows that women aged 40 to 49 years undergoing screening mammography are consistently diagnosed earlier and may have a reduction in risk of death from breast cancer of approximately 16% or even greater if strictly compliant. However, there needs be a discussion of both the potential risks of radiation from mammography as well as the benefits of early detection if a cancer exists," said Lyman, professor of Medicine and Oncology at the James P. Wilmot Cancer Center.

Lyman and Djulbegovic studied 10 randomized controlled trials with nearly 400,000 women and found there was little change in estimated overall survival for women who initiated routine mammography testing in the 40 to 50 age range. In addition, mammography, which is the best technology currently available and universally accessible to women, is only approximately 85 percent accurate in most cases.

False-negative mammograms can provide unnecessary reassurance to women and delay diagnosis of breast cancer, whereas false positives may lead to unneeded invasive procedures. But the greatest uncertainty associated with mammography is the potential risk for radiation-induced breast cancer, according to the report.

While the overall reduction in death from breast cancer during the 10 to 15 years of follow-up in trials of screening mammography is clear, the anticipated peak for radiation-induced breast cancer occurs some 10 to 20 years after exposure, and the increased risk might extend throughout a woman's life, the report said.

The report concludes that although the best estimates of harm associated with screening mammography seem to be less than the benefits, they remain too uncertain to conclude with a high level of confidence that mammography in this age group has a consistent net benefit.

"Each woman needs to have a very personal discussion with her doctor about the potential risks and benefits of undergoing mammography before they reach 50," Lyman said. "They need to decide whether the benefits outweigh the risks and the decision may be different for each woman. Clearly, if a young women's risk of breast cancer is at all increased due to family history and other factors, the benefit will almost always outweigh any risk."

University of Rochester Medical Center