Breast density measurements can be cancer prevention tool

Measuring breast density improves the accuracy of tests used to assess a woman's risk for breast cancer and helps guide doctors in recommending treatment that saves lives, researchers said.

Dense breasts, those containing more fibrous tissue, milk glands and breast cells than fat, are linked to a four- to fivefold risk of cancer, said Steven Cummings, director of the San Francisco Coordinating Center at the California Pacific Medical Center Research Institute and the study's lead author. His study is published in the Journal of the National Cancer Institute.

Doctors may advise women with dense breasts to have additional imaging tests like MRIs, or trim their risk by taking preventive drugs like tamoxifen and raloxifene, said Cummings, who recommends density readings be added to a woman's regular mammogram. Women may also adopt lifestyle measures such as exercising, losing weight and reducing alcohol intake, which can reduce cancer risk.

Density readings represent "a new approach for prevention of breast cancer for the general population, not just the 1 percent to 2 percent of women with genetic mutations," said Cummings in an interview.

In 2008, 182,460 women developed invasive breast cancer and 40,480 died of the disease in the United States, the American Cancer Society estimates. Other risk factors include age, family history, being childless, having one's first child after 30, recent birth control use and a mutation of the BRCA gene.

Mammograms, X-rays of the breast recommended for women over 40, picture dense tissue as bright white areas highlighted against a black background of fatty tissue. The research, a review of more than 50 studies, is the first systematic analysis of breast cancer risk models, Cummings wrote in the report.

The next step would be for radiologists, specialists who read a woman's mammogram, to quantify density and add it to their report so a physician can counsel her, Cummings said. That might add $20 to $30 to the cost of a mammogram, he estimated.

Technical hurdles making this practical include developing a standardized system for density reporting and securing insurance reimbursement, Cummings added. He and his colleagues are now recruiting more than 250,000 women for a multi-center study validating the findings on density and risk.