Have you ever had a mammogram and received the report from your radiologist with the words “dense breast tissue” written in the summary? If you were confused by this, you’re not alone.

Dense breast tissue is a significant risk factor for breast cancer. So much so that many states, including California, now require that all women who have dense breasts be informed of this either by letter or on their mammogram report.

It is essential that women and their physicians understand how breast density affects breast cancer risk and screening. As of December 2014, 18 states had passed breast density laws to help improve public knowledge surrounding breast density by requiring radiologists to inform patients when mammography reveals dense breast tissue.

Despite these developments, several recent surveys suggest that neither patients nor physicians fully understand the relationship between dense breast tissue, breast cancer risk, and breast cancer screening.

What are dense breasts? Women are increasingly asking this question as the topic of breast density receives attention from the media, state legislatures and Congress.