Study shows need for improved breast density awareness

Volume 4, Issue 2, 2015


Many women don't know that increased breast density can mask cancers on mammograms.

Photograph of Deborah J. Rhodes, M.D.

Deborah J. Rhodes, M.D.

Roughly half of U.S. women surveyed don't understand what breast density is or why it's important in breast cancer screening, according to the results of a Mayo Clinic Cancer Center study published in the April 1, 2015, issue of the Journal of Clinical Oncology.

The term "breast density" is the term used to describe the variation in dense tissue on a mammogram image. Fatty breast tissue appears more radiologically translucent than does dense (fibroglandular) breast tissue. Regions of a breast that comprise fatty tissue appear darker on a mammogram, while regions that comprise dense tissue appear whiter.

Increased breast density has been shown to mask cancers on mammograms and has been associated with future risk of breast cancer. Recent legislation in several states mandates that women be given information about breast density to guide decisions about breast cancer screening.

Mayo Clinic researchers conducted a national cross-sectional survey of 2,311 women ages 40 to 74 in English and Spanish. Overall, 58 percent of women who responded had heard of breast density, 49 percent were aware that breast density affects breast cancer detection and 53 percent knew that breast density is associated with cancer risk.

When researchers examined the survey results for race and ethnicity, they found increased breast density awareness among white, non-Hispanic women compared with minority women.

Increased awareness was also associated with women with higher household incomes, women with higher education, women who had received a diagnostic evaluation after a mammogram and women who received postmenopausal hormone therapy.

"The results of our study support the need for continued efforts to improve awareness of breast density and its implications on screening among women who are eligible for screening mammograms," said the study's lead author, Deborah J. Rhodes, M.D., a consultant in Preventive Medicine at the Mayo Clinic Cancer Center.

Dr. Rhodes and her colleagues also found that respondents from Connecticut were more likely than residents of other states to be aware of the potential masking effect of breast density on mammographic detection of cancer and were more likely to have discussed breast density with a health care provider.

In 2009, Connecticut became the first state to pass breast density legislation. To date, legislation mandating disclosure of breast density information has been passed in 21 states.