Family History Associated With Breast Cancer Risk for Women 65 and Older

First-degree family history is associated with increased risk of invasive breast cancer in all sub-groups of older women irrespective of a relative’s age at diagnosis, according to a study published in JAMA Internal Medicine.

“Evidence of the association between first-degree family history and the risk of invasive breast cancer among women 65 years and older is limited,” wrote the authors of the study. “Although family history is a strong risk factor for breast cancer among younger women, controversy exists about the magnitude of the association between family history and breast cancer among older women.”

According to the authors, it has yet to be determined if the association of first-degree family history with breast cancer among older women varies by age and breast density. Using data from 7 registries from the population-based US Breast Cancer Surveillance Consortium prospective cohort study, the authors extracted information about the population of women presenting for screening mammography.

A total of 472,220 mammograms from 403,268 women aged 65 and older who had at least 1 mammogram with self-reported information about first-degree family history between 1996 and 2012 were included in the study. Risk factor information was collected from the self-reports and included age, family history in a first-degree relative, race/ethnicity, weight, and height.

During the mean follow-up of 6.3 years, 10,929 invasive breast cancers were diagnosed. Results showed that the 5-year cumulative invasive breast cancer rates per 1000 persons increased with first-degree family history and age among women with heterogeneously or extremely dense breasts. For women aged 65 to 74 with a family history, there were 27 cases for every 1000 persons versus 20 for women without a family history; for women aged 75 and older with a family history, there were 28 for every 1000 persons, versus 18 for women without a family history.

Results also showed that the estimate per 1000 persons for women aged 65 to 74 with first-degree relative’s diagnosis at younger than 50 years was 28 (95% Cl, 23-25) versus 24 (95% Cl, 20-28) for women with relatives diagnosed at age 50 or older. The estimate per 1000 for women aged 75 or older with first-degree relative’s diagnosis age at younger than 50 years was 26 (95% Cl, 18-32) versus 27 (95% Cl, 23-33) for women with relatives who received a breast cancer diagnosis at age 50 or older.

For women aged 65 to 74, the risk associated with first-degree family history was highest among those with fatty breasts (HR, 1.67; 95% Cl, 1.27-2.21), while for women aged 75 and older, the risk was highest among those with dense breasts (HR, 1.55; 95% Cl, 1.29-1.87).

“Based on this pattern of findings, clinicians should continue to ask older women about family history of breast cancer to personalize mammography screening strategies,” concluded the authors. “Crucially, family history needs to be taken into account when considering the potential benefits versus harms of continued mammography in this population.”

Reference

Braithwaite D, Miglioretti D, Zhu W, et al. Family history and breast cancer risk among older women in the breast cancer surveillance consortium cohort. JAMA Intern Med. Published online February 12, 2018. doi: 10.1001/jamainternmed.2017.8642.