May 18, 2018
2 min read

Women with family history of breast cancer demonstrate increased risk regardless of genetic mutations

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Family history of breast cancer increased risk for contralateral breast cancer among younger women, even when those who had deleterious genetic mutations were excluded, according to study results.

“Compared with women without a family history, those with a positive family history have a two- to fourfold increased risk [for] developing breast cancer, which depends on the number of affected relatives and their ages at diagnosis,” Anne S. Reiner, MPH, senior research biostatistician at Memorial Sloan Kettering Cancer Center, and colleagues wrote. “The Women’s Environmental Cancer and Radiation Epidemiology (WECARE) Study is a population-based, case-control study of contralateral breast cancer cases and matched controls with unilateral breast cancer. ... The completion of the second phase of WECARE allows us to clarify the relationship between family history of breast cancer and contralateral breast cancer risk.”

The WECARE study compared 1,521 cases of contralateral breast cancer with 2,212 individually matched cases of unilateral breast cancer. All patients were aged younger than 55 years and received their diagnoses between 1985 and 2008.

Reiner and colleagues interviewed women about various risk factors for breast cancer — including family history — and screened a subset for BRCA1 and BRCA2 mutations, as well as deleterious mutations in ATM, CHEK2*1100delC and PALB2.

The researchers calculated cumulative absolute risks by combining the risk ratios from the WECARE study and population-based cancer incidence from the SEER*Stat database.

Women who had any first-degree relative with breast cancer demonstrated an 8.1% (95% CI, 6.7-9.8) 10-year absolute risk for contralateral breast cancer. This risk increased if the relative’s diagnosis occurred at age younger than 40 years (10-year absolute risk, 13.5%; 95% CI, 8.8-20.8) or if the relative received a contralateral breast cancer diagnosis (10-year absolute risk, 14.1%; 95% CI, 9.5-20.7).

These risks appeared similar to those seen in women with BRCA1 or BRCA2 mutations (10-year absolute risk, 18.4%; 95% CI, 16-21.3).

Risk estimates for women with a first-degree relative who had cancer remained unchanged in a subset of women who tested negative for deleterious genetic mutations. Risks also remained the same after researchers adjusted for known breast cancer single-nucleotide polymorphisms.

“Family history of breast cancer is relatively easy to assess accurately and — even in the absence of genetic testing — can inform the assessment of contralateral breast cancer risk and influence first primary breast cancer treatment decisions, such as prophylactic surgery or systemic therapy,” the researchers wrote. “Clinicians are urged to obtain and use detailed family histories from young women diagnosed with breast cancer to guide treatment and future screening decisions.” – by Andy Polhamus


Disclosures: Reiner reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.