Breast cancer risk elevated in older women with first-degree family breast cancer history
Women older than 65 years with a first-degree family history of breast cancer* have an elevated risk of invasive breast cancer themselves, according to results from a recent study.
“[W]e found that first-degree family history remained an important risk factor for breast cancer even among women older than 75 years and that breast density did not significantly modify the association except perhaps in women with fatty breasts,” said the researchers.
The prospective cohort study was conducted between 1996 and 2012 using data from seven Breast Cancer Surveillance Consortium (BCSC) registries in the US. Based on the mammograms of 403,268 women aged ≥65 years, a total of 10,929 cases of invasive breast cancer were diagnosed over the mean 6.3-year follow-up period.
Women aged 65–74 years with a first-degree family history of breast cancer had an increased risk of breast cancer themselves (hazard ratio [HR], 1.48, 95 percent confidence interval [CI], 1.35–1.61), as was the case with women aged ≥75 years (HR, 1.44, 95 percent CI, 1.28–1.62). [JAMA Intern Med 2018;doi:10.1001/jamainternmed.2017.8642]
The association between family history and cancer risk was similar regardless of whether the first-degree relative was diagnosed with breast cancer before or after age 50 years (HR, 1.47 and 1.33, respectively for first-degree relative diagnosis at age <50 and ≥50 years, respectively in women aged 65–74 years and HR, 1.31 and 1.55 for first-degree relative diagnosis at age <50 and ≥50 years, respectively in women aged ≥75 years).
Breast density did not modify the link between family history and breast cancer, with a possible exception among women aged ≥75 years, where women with dense breasts and a first-degree family history of breast cancer had a slightly higher risk than those with fatty breasts (HR, 1.55 vs 1.08).
“Family history of breast cancer does not decline as a breast cancer risk factor as a woman ages. The relationship didn’t vary based on whether a first-degree relative’s diagnosis was made in a woman age 50 or younger, or older than age 50,” said study lead investigator Associate Professor Dejana Braithwaite from the Georgetown University School of Medicine, Washington DC, US.
“This means that women with that first-degree family history – breast cancer in a mother, sister, or daughter – should consider this risk factor when deciding whether to continue mammography screening as they age,” she said.
According to the researchers, while family history is a strong risk factor for breast cancer in younger women, its role in the risk of breast cancer in older women has not been not established.
“As breast cancer screening guidelines change from age-based to risk-based, it is important to know how standard risk factors impact breast cancer risk for women of different ages,” said study co-author Dr Karla Kerlikowske from the University of California San Francisco Helen Diller Family Comprehensive Cancer Center, San Francisco, California, US.
“Although family history is not a modifiable risk factor, evaluating its impact is paramount for refining risk prediction tools and identifying high-risk older women for continued and potentially tailored mammography screening strategies,” said the researchers, recommending further study into identifying the mechanisms behind the family history-breast cancer risk link in older women.
“The goal of our work is to provide evidence that helps inform breast cancer screening guidelines for older women. Older women who are in good health and have a first-degree family history may consider a screening mammogram even as they age beyond the screening recommendations for average risk women,” said Braithwaite.