Feds test whether 3-D mammograms better than X-rays
Washington — A better mammogram? Increasingly, women are asked if they want a 3-D mammogram instead of the regular Xray — and now U.S. health officials are starting a huge study to tell if the newer, sometimes pricier choice really improves screening for breast cancer.
It’s the latest dilemma in a field that already vexes women with conflicting guidelines on when to get checked: Starting at age 40, 45 or 50? Annually or every other year?
The issue: Mammograms can save lives if they catch aggressive breast cancers early. But they also can harm through frequent false alarms and by spotting tumors that grow so slowly they never would pose a threat — overdiagnosis that means some women undergo unneeded treatment.
That trade-off is a key question as doctors begin recruiting 165,000 women nationally to compare potentially more beneficial 3-D mammograms — known scientifically as “tomosynthesis” — with standard two-dimensional digital mammography.
The 3-D mammograms have been marketed as being able to find more cancers.
“But the idea isn’t so much finding more cancers as finding the cancers that are going to be life-threatening,” said Dr. Worta McCaskill-Stevens of the National Cancer Institute, which is funding the new research to tell whether the 3-D scans pinpoint the tumors that matter most.
It’s one of the largest randomized trials of mammography in decades, and scientists designed the research to do more than answer that key 3-D question. They hope the findings also, eventually, will help clear some of the con- fusion surrounding best screening practices.
Who needs mammogram?
That depends on whom you ask. Guidelines vary for women at average risk of breast cancer. (Those at increased risk, because of family history or genetics, already get different advice.)
The American College of Radiology recommends annual mammograms starting at age 40.
The American Cancer Society urges annual checks starting at 45 and switching to every other year at 55, though it says women 40-44 still can opt for a mammogram.
And the U.S. Preventive Services Task Force, a government advisory group, recommends starting at age 50, with mammograms every other year. It, too, says 40-somethings can choose earlier screening.
Standard mammograms take X-rays from two sides of the breast. With tomosynthesis, additional X-rays are taken at different angles — not truly three-dimensional but a computer compiles them into a 3-D-like image. Approved by the Food and Drug Administration in 2011, they’re not yet the standard of care in part because of questions that the new study aims to answer.
How to decide?
Understand that mammograms come with pros and cons, and weigh them, said Dr. Otis Brawley, the American Cancer Society’s chief medical officer.
Consider: For every 1,000 women screened every other year until their 70s, starting at 40 instead of 50 would prevent one additional death — but create 576 more false alarms and 58 extra unneeded biopsies, the task force estimated.
Dr. Tova Koenigsberg at The Montefiore Einstein Center for Cancer Care in New York shows an example of a traditional mammogram scan. Officials are beginning to compare traditional tests with 3-D versions.