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    Studies Point to Reasons for Mammograms in 40s

    Women With Dense Breasts or a Family History of Breast Cancer May Want to Consider Screening in Their 40s

    Family History or Dense Breast Tissue Doubles Risk continued...

    Out of 13 distinct risk factors identified through the studies and registries, only two fully doubled a woman's risk for breast cancer in her 40s.

    "To have a twofold increase in risk, you need to have a first-degree relative -- a mother, daughter, or sister -- with breast cancer. Or you need to have extremely dense breasts. There aren't that many women who have either of those conditions," Mandelblatt says.

    For women with more than one first-degree relative with breast cancer, the risks were even higher -- four to 12 times greater than average.

    If a first-degree relative was diagnosed before age 40, a woman's risk of breast cancer was three times higher than average.

    The issue of breast density is a complicated one, researchers admit, because density can only be determined by first getting a mammogram.

    Experts don't recommend that women get a baseline mammogram to discover breast density.

    "Mammography density is sort of a newer area," says researcher Heidi D. Nelson, MD, MPH, an investigator at the Oregon Evidence-based Practice Center and the Knight Cancer Institute at Oregon Health & Science University in Portland.

    "Radiologists aren't in good agreement about how to read breast density, and we're not sure how to drive that car, yet, really," Nelson says. "So it would be good to maybe wait for more research about exactly how to make decisions with that information."

    But Nelson says the study should also comfort women who worry that things like physical inactivity and body weight might put them at increased risk for breast cancer. The study found those had relatively little influence on a person's risk. Other factors that didn't appear to raise risk substantially included race, smoking, and alcohol use.

    "What's really reassuring is that there are a lot of risk factors that really don't have a huge increase in risk attached to them," says Nelson.

    Understanding Personal Risk

    Researchers were also careful to stress that the pair of studies was meant for policy makers, not for individual women to use to try to discern their own risk.

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