Q: I get mammograms about once every 18 months. Fortunately, they have always been normal. But my most recent report again said normal but added that I have dense breasts. Why the change and what does that mean for me?
A: Density is important because having high breast density is a risk factor for breast cancer and also can make it more difficult for a radiologist to see a cancer on a mammogram.
The FDA is proposing a change that would require all require mammography facilities to provide letters to women and their doctors explaining breast density findings and what they mean. The final ruling has not yet been released.
Many states already require doctors or mammography facilities to tell patients if they have high breast density. Perhaps you moved to a different state or your state changed their mammogram reporting requirements ahead of the FDA's ruling.
While doctors know that women with high density are slightly more likely to develop breast cancer, there is no consensus yet on how to respond to that risk. Should women with high density be screened at a younger age, more often, or using different technology? But there's a problem.
There's no official recommendation on what women should do. We don't yet have the high-quality research data to advise women with higher breast density whether they should be screened or monitored differently.
In dense breasts, there are more of the active tissues -- lobules and ducts that produce and secrete milk -- and less fat. One theory as to why women with higher breast density have a higher risk of cancer is that they have more of the type of tissue where cancers most often start -- namely in epithelial cells in the breast. Epithelial cells are found in the lining of the structures that produce milk.
Breast density isn't necessarily a fixed trait; it often changes over time. Younger women typically have higher density than older ones, and density typically declines after menopause. But this is not always the case. Some older women still have dense breast tissue. Taking hormone therapy may also increase breast density.
The finding of dense breasts can be confusing and stressful. Talk with your doctor. Find out where on a scale of 1 to 4, the radiologist classified your breast density (a level 3 or 4 is considered high). Whether to do additional tests or change your screening schedule, your doctor will consider other breast cancer risk factors, such as your age, your family history, and your race.
If the breast density is measured lower, at only a 1 or 2, and you are otherwise at average risk for a woman your age, you may not need any change in your current screening program.
(Howard LeWine, M.D., is an internist at Brigham and Women's Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)