Having dense breasts — that is, relatively little fat in the breast and more glandular and connective tissue, as seen on a mammogram — is one of the strongest known risk factors for breast cancer. A recent study finds that higher breast density also boosts the risk of some aggressive types of breast cancer in postmenopausal women, reports the October 2011 issue of Harvard Women’s Health Watch.

Using data from the Nurses’ Health Study, Harvard researchers found that the link between breast density and breast cancer was stronger for cancer confined to the ducts and lobules (in situ tumors) than for invasive cancer. But it was also stronger for certain breast cancers associated with poorer outcomes, including larger tumors, high-grade tumors, and estrogen receptor–negative tumors (which are more likely to grow and spread than estrogen receptor–positive tumors).

Breast density is largely out of a woman’s control, says Harvard Women’s Health Watch, but postmenopausal women who have dense breasts should keep the following in mind:

• Breast density is an important risk factor, but it’s not the only one. You and your clinician should discuss your risk profile and plan screenings and office visits accordingly.
• Mammograms are less sensitive for you than for women with less dense breasts, so you’re more likely to be called back for additional mammograms or images using a different method.
• Hormone therapy increases breast density, so if you’re considering it, you may want to explore other options.
• If you have a high overall risk for breast cancer, you may want to talk to your clinician about chemoprevention with tamoxifen, which can reduce breast density.
• Mammograms are the main focus of breast cancer detection, but almost half of breast cancers in women ages 50 to 69 are found by the women themselves or their clinicians. So be familiar with the architecture of your breasts, and bring any changes to your clinician’s attention.

Read the full-length article: "The breast density–breast cancer connection"