3-D mammograms: An improvement?

WASHINGTON» A better mammogram? Increasingly women are asked if they want a 3-D mammogram instead of the regular X-ray — 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 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 have posed 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 truly 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 confusion surrounding best screening practices.

“The most important thing about this study is that it’s moving us to individualized screening as opposed to what we have now, which is one-size-fits-all screening,” predicted study chair Dr. Etta Pisano, a radiologist at Boston’s Beth Israel Deaconess Medical Center.

“We are going to have a much better understanding of how to screen women so that we do the least amount of harm.”