Radiologists divide density levels into four categories. According to the American College of Radiology, about 10 percent of women have almost completely fatty breasts. Another 10 percent have extremely dense breasts, the level that Kerlikowske said is linked to a higher risk of developing cancer. The rest are in between, with about 40 percent having scattered areas of density and 40 percent having fairly widespread density, categories especially difficult to classify.
"We're making policy in a gray area where the experts and doctors don't know what it means," said a frustrated Brawley.
To help women make sense of the debate, the American College of Radiology this month developed a brochure for mammography centers to distribute: http://tinyurl.com/cpuvpwe .
UCSF's Kerlikowske said knowing you have dense breasts could be valuable, if the information is used properly. It's one more factor to weigh along with things like whether your mother or sister had breast cancer, if you've had previous biopsies, and your reproductive history — all information that helps doctors determine your overall risk.
Beyond that, Kerlikowske is leading a major study to try to determine the best screening approach for women with high breast density and a variety of risk factors.
"I hope in a year or two we can make some intelligent recommendations," she said.
EDITOR'S NOTE — Lauran Neergaard covers health and medical issues for The Associated Press in Washington.
Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.