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This story gives people even more to think about when they think about mammograms. Sometimes a mammogram gives the wrong test result and the wrong result eventually turns out to be right. I'm just going to say that again. You take a test, it falsely shows signs of cancer, yet people who had false results are slightly more likely to develop cancer later. That's according to a new study in a journal of the American Association for Cancer Research. Here's NPR's Patti Neighmond.
PATTI NEIGHMOND, BYLINE: Mammograms are important tools for detecting breast cancer. But they can also cause unnecessary distress, turning up false alarms, what doctors call false positives. Epidemiologist Louise Henderson with the University of North Carolina School of Medicine.
LOUISE HENDERSON: Over the course of, say, 10 years of annual screening or biannual screening, it's estimated that about 50 percent of women will experience a false positive finding.
NEIGHMOND: And that typically leads to further testing, more mammograms, maybe ultrasounds, MRIs, even biopsies. And a false positive is what it sounds like. It's a positive finding for cancer but it's false. Henderson's also a breast cancer screening researcher, and she wanted to see what happened to women down the road up to 10 years after having a false positive mammogram. She analyzed medical records for 1.3 million women across the country.
HENDERSON: We found that women who had a false positive mammogram had an increased risk of subsequently developing breast cancer compared to women who did not have a false positive finding.
NEIGHMOND: Now Henderson says it's important to note the increase was small - about one additional case of cancer out of every 100 women who had a false positive mammograms. But it is an increase in cancer risk nonetheless, she says. Her study was not able to explore why this may be the case.
HENDERSON: The increased risk could be the fact that the radiologist sees an abnormal pattern that's not cancerous but it's a radiographic marker. And it could be that that is a precursor to some subsequent cancer diagnosis.
NEIGHMOND: Henderson says the findings should help doctors determine overall cancer risk for their patients, along with other known risk factors, like age, breast density and family history. This is not the first study to look into false positive mammograms and breast cancer risk. But it's the largest, says Dr. Richard Wender, chief cancer control officer at the American Cancer Society.
RICHARD WENDER: The most important message here is that if you've had a false positive, that is a risk factor - a small one but a real one - to be at higher risk for a breast cancer diagnosis in the future. So it's very important that a woman stay up to date with regular mammography.
NEIGHMOND: The American Cancer Society recently revised its recommendations for breast cancer screening, and now says women don't need to start getting yearly mammograms until they turn 45. Other groups recommend other start dates. Even so, Wender says the conversation should begin at age 40 with a woman and her doctor evaluating all risk factors and deciding whether to start mammography earlier.
WENDER: But if you've had a false positive, it's even more important that a woman remain vigilant and their clinician and the entire health care system help her remain vigilant to be regularly screened.
NEIGHMOND: As it is now, Wender says at least one-third of women who should be getting routinely screened for breast cancer are falling behind in their recommended mammogram schedule. Patti Neighmond, NPR News.
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