Why breast density matters

Your radiologist or doctor may have told you after a routine mammogram that you have dense breasts. But what are dense breasts exactly, and how can they affect the risk of breast cancer? Simply put,

"Women with dense breasts have more mammary tissue than fatty tissue," explains Dr. Robyn Birdwell, Harvard Medical School's associate professor of radiology, and section head in the Brigham and Women's Hospital breast imaging division. If more than 50% of your breasts consists of connective and glandular breast tissue (as opposed to fat), then dense breasts are present. Approximately 40% of women have dense breasts.

Why is your breast density important? Women with dense breasts are likely to develop breastcancer slightly higher. And if you develop breast cancer, dense breasts can make it more difficult to spot cancer, because on a mammogram both glandular breast tissue and tumours appear white. Imagine watching a black glove snowflake. You can make out some of its crystals in detail against the dark fabric. Then take the same flakes and put them in a snow bed. Now, distinguishing the flakes from their background becomes difficult. That's the challenge that radiologists face when they try to read a woman's dense breast mammograms.

A study presented at the North American Radiological Society meeting in November 2012 found that more than three-quarters of women did not know their breast density status, but 95 percent said they would want additional screening if they found out they had dense breasts. Talk to your gynaecologist or general practitioner about your overall risk of breast cancer development. Together, you can determine which screening tests you need, how often you should be screened, and what strategies of prevention you should follow.