Women should know their breast density, study says; how many do?

Mammograms should be recommended to women based on several individual risk factors, such as age, family history and breast density, doctors said in a study published Monday in the Annals of Internal Medicine.

But how many women know their breast density?

Under legislation proposed in California, every woman who has a mammogram would also receive information on her breast density. Studies have confirmed that having more high-density tissue, which has less fat, raises breast cancer risk while having more low-density tissue lowers it.

The proposed legislation, Senate Bill 173, is opposed by several medical groups, however. In a recent statement, the American Congress of Obstetricians and Gynecologists of District IX, the California Radiological Society, the California Medical Assn. and other groups say they oppose the bill.


While the legislation is designed to empower women, opponents say it is too vague and may lead to additional, unnecessary tests. They argue that there is not yet clarity on what “dense breasts” actually means.

That opinion doesn’t mesh with the study reported Monday, which gives significant value to understanding breast density.

“Breast density is the strongest risk factor that we know of, stronger than age and family history,” said Dr. Steven R. Cummings, senior author of the study and senior researcher at the California Pacific Medical Center Research Institute, part of the Sutter Health network. “We now have a lot more information about breast cancer risk. So we’re able to analyze the relationship between breast density and the risk of getting breast cancer very, very accurately.”

Most medical organizations, including the American Cancer Society, recommend healthy women undergo screening every one to two years beginning at age 40 regardless of risk factors. In 2009, the U.S. Preventive Services Task Force recommended a more relaxed schedule, saying screening for women 40 to 49 should be based on individual risk factors and women ages 50 to 74 should be screened every two years.

But those guidelines are trying “to make one-size-fits-all while we think of this as a personalized approached to mammography,” Cummings said.

To move toward a more personalized mammography recommendation, women will need to know their breast density, he said.

“Right now, it’s not easy to apply what we’ve concluded,” Cummings said. “But within a year, California women may get a report on their breast density. What will be needed then is for doctors to refer to the guidelines we’ve laid out.”

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