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Family history increases breast cancer risk regardless of age

First-degree family history was associated with a significantly increased risk for invasive breast cancer among older women regardless of a relative’s age at
diagnosis, according to a study published in JAMA Internal Medicine.

Another study, also published in JAMA Internal Medicine, revealed that women with and without a personal history of breast cancer who undergo screening via MRI experience higher biopsy rates and lower cancer yield those who are screened via mammography.

“First-degree family history is a strong risk factor for breast cancer, but controversy exists about the magnitude of the association among older women,” Dejana Braithwaite, PhD, from department of oncology at Georgetown University, and colleagues wrote.

Between 1996 and 2012, Braithwaite and colleagues investigated whether first-degree family history and breast density impacts the risk of breast cancer among older women. The cohort consisted of 403,268 women aged 65 years and older. Among these women, 10,929 invasive breast cancers were diagnosed during a mean follow-up period of 6.3 years.

The researchers found that risk for breast cancer increased in women with first-degree family history who were aged between 65 and 74 years (HR = 1.48; 95% CI, 1.35-1.61) and 75 years and older (HR = 1.44; 95% CI, 1.28-1.62).

Women aged 65 to 74 years whose first-degree relative was diagnosed at age younger than 50 years (HR = 1.47; 95% CI, 1.25-1.73) and at 50 years and older (HR = 1.33; 95% CI, 1.17-1.51) displayed similar estimates, as did women aged 75 years and older whose first-degree relative was diagnosed at age younger than 50 years (HR = 1.31; 95% CI, 1.05-1.63) and at 50 years and older (HR = 1.55; 95% CI, 1.33-1.81).

The risk for breast cancer associated with family history was highest in women aged 65 to 74 years with fatty breasts (HR = 1.67; 95% CI, 1.27-2.21) and women 75 years and older with dense breasts (HR = 1.55; 95% CI, 1.29-1.87).

“Family history of breast cancer does not decline as a breast cancer risk factor as a woman ages,” Braithwaite said in a press release. “The relationship didn’t vary based on whether a firstdegree relative’s diagnosis was made in a woman age 50 or younger, or older than age 50. This means that women with that firstdegree 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.”

In a separate study, Diana S. M. Buist, PhD, MPH, from Kaiser Permanente, and colleagues evaluated the biopsy rates and yield in the 90 days after screening among women with and without a personal history of breast cancer.

“There is little evidence on population-based harms and benefits of screening breast MRI in women with and without a personal history of breast cancer,” the researchers wrote.

Buist and colleagues enrolled 812,164 women who underwent screening via mammography or MRI with or without mammography between 2003 and 2013. They studied 101,103 mammography screening episodes in women with a personal history of breast cancer and 1,939,455 in those without a personal history, as well as 3,763 MRI screening episodes in women with a personal history of breast cancer and 4,673 in those without a personal history.

Data indicated that in women with a personal history of breast cancer, the rates of age-adjusted core and surgical biopsies per 1,000 episodes increased twofold after an MRI (57.1; 95% CI, 50.3-65.1) compared with mammography (23.6; 95% CI, 22.4-24.8). In women without a personal history of breast cancer, the differences in these rates after MRI (84.7; 95% CI, 75.9-94.9) vs. mammography (14.9; 95% CI, 14.7-15) were even greater.

There was a significantly higher ductal carcinoma in situ and invasive biopsy yield per 1,000 episodes after mammography (404.6; 95% CI, 381.2-428.8) than MRI (267.6; 95% CI, 208-337.8) in women with a personal history of breast cancer. Ductal carcinoma in situ and invasive biopsy yield per 1,000 episodes was also higher after mammography (279.3; 95% CI, 274.2-284.4) compared with MRI (214.6; 95% CI, 158.7-280.8) in women without a personal history of breast cancer; however, these results were nonsignificant.

Regardless of personal history of breast cancer status, MRI identified more high-risk benign lesions than mammography. Following MRI, there were higher biopsy rates and lower cancer yield. The researchers noted that this could not be justified after accounting for age or 5-year breast cancer risk.

“Further work is needed to identify women who will benefit from screening MRI to ensure an acceptable benefit-to-harm ratio,” Buist and colleagues concluded. “Women who undergo screening MRI should also be notified that their likelihood of undergoing a core or surgical breast biopsy is significantly higher than for women undergoing mammography alone, with a lower likelihood of clinically actionable findings.” – by Alaina Tedesco

Disclosure: The authors report no relevant financial disclosures.