Family history of breast cancer linked to persistently increased breast density

Key takeaways :

• Women with a family history of breast cancer had 22% increased odds for dense breasts.
• Odds of developing dense breasts were higher among women with family history of breast cancer compared with those without.

Among premenopausal women in Korea, family history of breast cancer was positively associated with increased breast density and persistently dense breasts over time, according to findings published in JAMA Network Open.

“Recent studies have suggested that increased breast density over time is associated with a higher risk of breast cancer, whereas decreased breast density is associated with a reduced risk of breast cancer,” Thi Xuan Mai Tran, PhD, from the department of preventive medicine at Hanyang University College of Medicine, Seoul, South Korea, and colleagues wrote. “Thus, we hypothesized that premenopausal women with [family history of breast cancer] have a high likelihood of having dense breasts and increased breast density over time or having persistently dense breasts.”

Using population-based data from the National Health Insurance Service-National Health Information Database of Korea, researchers conducted a retrospective cohort study of 1,174,214 premenopausal women who underwent mammography for breast cancer screening once between 2015 and 2016 and 838,855 women who underwent mammography twice between 2015 and 2018.

The primary outcome was breast density based on the Breast Imaging Reporting and Data System categorized as dense or nondense.

Overall, 2.4% of women (mean age, 46.3 years) reported having family history of breast cancer among their first-degree relatives while the rest of the women reported no family history of breast cancer. Women with a family history of breast cancer had 22% higher odds of having dense breasts (adjusted OR = 1.22; 95% CI, 1.19-1.26) compared with women without a family history of breast cancer. This association varied by affected relatives: mother alone (aOR = 1.15; 95% CI, 1.1-1.21), sister alone (aOR = 1.26; 95% CI, 1.22-1.31) and both mother and sister (aOR = 1.64; 95% CI, 1.2-2.25).

Women with family history of breast cancer continued having higher odds of dense breasts when researchers analyzed a subgroup of women aged 40 to 44 years (OR = 1.17; 95% CI, 1.12-1.23), 45 to 49 years (OR = 1.25; 95% CI, 1.20-1.31) and 50 to 55 years (OR = 1.24; 95% CI, 1.17-1.31) vs. women with no family history of breast cancer.

Among those with fatty breasts at baseline, women with a family history of breast cancer had 19% higher odds of developing dense breasts compared with those without (aOR = 1.19; 95% CI, 1.11-1.26). Researchers also observed 11% higher odds of having persistently dense breasts among women with dense breasts and a family history of breast cancer compared with those without such a family history (aOR = 1.11; 95% CI, 1.05-1.16).

“These findings indicate that family history of breast cancer, as an index of aggregation of genetic factors, is associated with mammographic breast density and its changing pattern in premenopausal women, suggesting the need for a tailored risk assessment for women with family history of breast cancer,” the researchers wrote.