Mammography Study Shows 22 Percent Higher Incidence of Dense Breasts in Women with a Family History of Breast Cancer

In a study of over one million Korean women, researchers found a significantly higher likelihood of increased breast density or persistent dense breasts for women who had a family history of breast cancer (FHBC).

For the retrospective study, published recently in JAMA Network Open, researchers reviewed data from a national insurance database of 1,174,214 premenopausal women (mean age of 46.3). The study authors noted that 34,003 women acknowledged first-degree relatives with a history of breast cancer.

Women with FHBC were 22 percent more likely to have dense breasts in comparison to women without FHBC, according to the study findings. When there was breast cancer history for a mother and a sister, the researchers found that women were 64 more likely to have dense breasts. The study authors noted that having a mother with breast cancer was associated with a 15 percent higher likelihood of dense breasts and having a sister with breast cancer was associated with a 26 percent higher likelihood of dense breasts.

“Our findings highlight that FHBC is an important risk factor for breast cancer; it is also associated with breast density and its increment or persistent density over time, suggesting aggregation of hereditary risk factors of breast cancer,” wrote Boyoung Park, M.D., Ph.D., who is affiliated with the Department of Preventive Medicine at the Hanyang University College of Medicine in Seoul, Korea, and colleagues.

(Editor’s note: For related content, see “FDA Issues Final Rule on National Breast Density Notification for Mammography Reports,” “Current Insights on National Breast Density Notification for Mammography Reports” and “Interval Breast Cancer: What a New Mammography Study Reveals.”

For women with FHBC and fatty breasts at an initial screening in the study, the researchers noted a 19 percent higher likelihood of developing dense breasts in comparison to women without FHBC. Park and colleagues also noted that women with FHBC were 11 percent more likely than women without FHBC to develop persistently dense breasts.

In regard to study limitations, the study authors acknowledged a lack of information in the cohort database on age at the time of breast cancer onset, the affected relative and first- or second-degree relatives, factors that can impact the association between breast density and family history of breast cancer. They noted the potential for recall bias with the family history of breast cancer being self-reported. Pointing out that women in the study could have had yearly or biennial breast cancer screening, the researchers assessed breast density changes within a two-year period.