If you’re among the roughly 50% of women with dense breasts, figuring out the best way to get screened for breast cancer can be mightily confusing. Consider…

• High breast density promotes tumor growth and is linked with increased breast cancer risk.

• Mammograms are more likely to miss a tumor. Why? Dense tissue appears white on mammography X-rays…and so do tumors. That makes them harder to spot.

• Women with dense breasts may opt for extra testing (ultrasound, MRI), which can pick up tumors that mammography misses, but these increase the risk for false-positive results—“suspicious” findings that turn out to be nothing but often lead to additional testing…biopsy…extra costs, not always fully covered by insurance…and plenty of anxiety.

Finally, there is a path out of this crazy maze. A major new study finds that not all women with dense breasts necessarily benefit from extra screening. Even better, there is now a scientifically validated tool that lets you figure out whether you should skip extra tests—or insist on them. Here’s what you need to know before having a discussion with your doctor about what level of screening is right for you.


Dense breasts have more fibrous and glandular tissue and less fat. If you have heterogeneously dense breasts, only parts of them are dense, and those parts are hard to read on a mammogram. If you have extremely dense breasts, most of the breast tissue is dense, and these are very hard to read on a mammogram.

To find out whether certain women with dense breasts would benefit most from supplemental screening, researchers from the National Cancer Institute’s Breast Cancer Surveillance Consortium analyzed screening data from 365,426 women. They specifically looked at interval cancers, which are cancers that were diagnosed within 12 months of a normal mammogram—so were not detected at the time of the last mammogram. These cancers tend to be more aggressive, making early diagnosis even more critical.

The researchers used a recently developed tool, the Breast Cancer Surveillance Consortium (BCSC) Risk Calculator, which can determine a woman’s five-year risk for a diagnosis of invasive breast cancer. For the women they studied, they entered in five known breast cancer risk factors—age (risk goes up significantly over 55)…race/ethnicity (whites are at highest risk, followed by blacks, with Asian, Hispanic and Native American women at lowest risk)…family history (if your mother, sister, or daughter had breast cancer, that increases risk)…and personal history of breast biopsy (an indication that something suspicious was found on a mammogram or other test that may increase risk)…and breast density.

The results: The researchers found that for about half the women with dense breasts, the five-year risk for interval cancer was low to average. In other words, just having dense breasts didn’t put you at high risk for invasive breast cancer.

However, if your risk profile based on the first four factors means that you are already at somewhat elevated risk, then having dense breasts may change the picture. Two groups were found to be at high risk for interval cancer, making them the best candidates for considering supplemental screening…

• Women who have a five-year risk of 1.67% or greater of getting interval breast cancer and extremely dense breasts.

• Women who have a five-year risk of 2.50% or greater and heterogeneously dense breasts.

These two high-risk groups made up just 24% of all women with dense breasts and just 12% of the entire screening population. The researchers also found that most of those women at high risk for interval cancer were also at high risk for advanced cancer, making further discussion of supplemental screening even more important for them.


The biggest takeaway here, says Karla Kerlikowske, MD, a professor in the departments of medicine and epidemiology and biostatistics at the University of California, San Francisco, is that digital mammography alone works well for most women—even women with dense breasts, as long as they’re otherwise at low risk.

To find out whether you should discuss supplemental screening with your provider—and if you’re between the ages of 35 and 79—you can use the BCSC Risk Calculator to start the discussion. It’s online here and available as an iPhone app (search for “BCSC Risk Calculator”). If you’re using it on your own, you’ll need to know your breast density category (if you’ve had a mammogram, your doctor can give you this information). After entering your data, the calculator will tell you your estimated risk for invasive breast cancer over the next five years. Then you can take this information to your doctor and discuss whether you need supplemental testing.

Keep in mind that even if you’re in one of the high-risk groups, supplemental screening can still turn up false-positives. So don’t panic if you are asked to come in for additional testing. If you’re in the low-risk group, you can probably continue to simply have regular digital mammogram screenings, although that is a decision that you should make in concert with your doctor (or doctors) based on all of your individual characteristics.

To learn more about ways to protect yourself, see Bottom Line’s articles,  “Dense Breasts Increase Your Cancer Risk—Here’s What Helps” and “Breast Cancer Guide: Prevent, Detect, Treat, Recover.”