Women with denser breasts based on their mammography scans have higher risks of test recall and tumors that can go undetected.
A large study from Norway looked at the mammography screening results of 107,949 women aged 50 to 69 years between 2007 and 2015. Researchers described that dense breast tissues appear white in mammogram scans, while fatty tissues look darker. This leads to a masking effect because tumors also appear white in breast scans.
The study is published June 26 in the journal Radiology.
Why Worry About Breast Density?
The authors used automated screening software instead of the Breast Imaging Reporting and Data System recommended by the American College of Radiology or BI-RADS. While BI-RADS is the most used guideline in breast density, the authors noted that assessments are often subjective to the radiologist's judgment.
Results showed that 28 percent of the 307,015 examinations are classified as dense breasts. Cancer rates are detected in 6.7 per 1,000 exams in women with dense breast tissues and 5.5 in those with non-dense breasts.
Those who have dense breasts are 3.6 percent more likely to go back for succeeding tests due to suspicious findings in their initial scans. Meanwhile, biopsy rates are 1.4 percent among women with dense breasts compared to 1.1 percent in those with non-dense breasts.
"The odds of screen-detected and interval breast cancer were substantially higher for women with mammographically dense versus fatty breasts in BreastScreen Norway," said the study's lead investigator Dr. Solveig Hofvind from the Cancer Registry of Norway.
Researchers also found that tumors are larger in dense breast tissue group with an average diameter of 16.6 millimeters. Twenty-four percent of women in this group tested positive for lymph node disease compared to 18 percent of women with non-dense breasts.
Precaution To Women With Dense Breasts
Liane Philpotts from Yale School of Medicine highlighted the importance of the study. The automated process can correctly identify the percentage of women with dense breast density. It also optimizes supplemental screening procedures for women who performed poorly in their mammograms.
"Dense breasts are not something that a patient feels. You can only tell if someone has dense breast tissue on a mammogram," Philpotts wrote in an accompanying editorial. "This study really shows that women with dense breasts did have more cancers. It wasn't a huge amount. It was a small increase, but it was an increase."
Experts advise taking precautionary measures for women who have denser breasts. These include regular exercise, limited alcohol intake, nutritious diet, healthy weight, and smoking cessation.