Many of us are getting to know our bodies a bit better these days. Because of medical outreach and news reports, more of us are now familiar with our blood pressure and cholesterol numbers. For women, another statistic that should be on that list is breast density.

Women whose breasts that appear dense on mammograms are at a higher risk of breast cancer and tumors than women with less dense breasts, according to a study published online July 27 in the Journal of the National Cancer Institute. Cancers in dense breasts are also more likely to have certain aggressive characteristics.

Breast density is determined by the proportions of fat, connective tissue and tissue that lines the cavities and surfaces of structures in the breast. Breast density is classified using the BI-RADS scoring method outlined by the American College of Radiology. This method describes four different categories:

BI-RADS I - Entirely fat BI-RADS II - Scattered fibroglandular densities BI-RADS III - Heterogeneously dense BI-RADS IV - Extremely dense

Two-thirds of premenopausal women and a quarter of post-menopausal women have dense breast tissue. Women with extremely dense breast tissue are at a four to six times greater risk of developing breast cancer. The big problem here is that mammograms may not be able to detect abnormalities in these dense tissues until it's too late.

A radiologist can determine a woman's breast density through a mammogram, but that finding is not always passed along to the patient. Some states now mandate that breast density results be communicated to patients. The laws also require that health care providers tell patients that dense breast tissue can also hide tumors on mammograms, may increase their risk of breast cancer and that they should ask their doctors whether further screenings, like a breast MRI or ultrasound may be in order.

Laws requiring disclosure have been passed in Connecticut, Texas and Virginia, and most recently in California and New York, where they take effect next year. Nearly a dozen other states are considering such legislation and a bill calling for a federal law has been introduced in the House.

A new statement to help physicians inform women on how breast density affects screenings and cancer risk has been issued by the American Society of Breast Disease.

“In our view, breast cancer screening today is best seen as a multidisciplinary process, not a single test,” according to Stephen A. Feig, M.D., FACR, ASBD's president. “As part of this process, we support women being informed participants, with their primary physicians and their OB/GYN specialists, in their breast health decisions. Besides making women more satisfied patients, this leads to better compliance and better outcomes.”

Even without legislation, most experts will tell you that women can freely ask about their breast density, since radiologists routinely report that information to physicians. If it were your blood pressure or cholesterol, you'd think nothing of it. So, ask your doctor. Every woman should know her BI-RADS breast density class.

Doneda Swenson is a certified breast navigator at The Breast Center at St. Mary's Medical Center. She can be reached at 816-655-5767.