DEAR DOCTOR K: After my last mammogram, the doctor told me I have dense breasts. Does this increase my risk of breast cancer?
DEAR READER: A woman’s breast contains different types of tissue, including fat. Women with dense breasts have relatively less fat in their breasts. Specifically, if more than 50 percent of your breasts is made up of other breast tissue (as opposed to fat), then by definition you are said to have “dense breasts.” It’s not uncommon: About 40 percent of women have dense breasts.
Women with dense breasts have a slightly increased chance of developing breast cancer – and dense breasts can make cancer harder to spot. That’s because both breast tissue and tumors appear white on a mammogram.
There now is a federal law that mammogram reports should always explicitly state whether a breast is “dense” or not.
So should you have additional screening tests for breast cancer? The trouble is, no test can diagnose breast cancer with 100 percent accuracy, especially in women with dense breasts. And the additional tests that I’m about to describe pick up a lot of “false positives”: The result looks like there might be cancer, requiring a biopsy that shows no cancer. Additional screening tests can also be costly.
If you do decide to have further screening, here are some options to consider:
• Ultrasound. In September 2012, the FDA approved a new breast ultrasound system specifically for screening dense breasts. This ultrasound scans the entire breast using high-frequency sound waves and quickly produces several images. If you were going to have additional testing, your doctor most likely will recommend this ultrasound.
• Magnetic resonance imaging (MRI) uses magnets and radio waves to visualize the breasts. It would not normally be recommended just because a woman has dense breasts because of the problem of false-positive results.
• Digital mammography sends X-ray images of the breast to a computer, rather than to film, making them easier to manipulate and interpret. A large study of nearly 50,000 women concluded that digital mammography was somewhat more accurate than regular film mammography in women with dense breasts.