Disclosures: NIH and the Breast Cancer Research Foundation supported the study. Domchek reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
October 07, 2021
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Older women with triple-negative breast cancer should undergo genetic testing

Disclosures: NIH and the Breast Cancer Research Foundation supported the study. Domchek reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
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Genetic testing for hereditary cancer should be offered to all women aged older than 65 years with triple-negative or ER-negative breast cancer, according to study results published in Journal of Clinical Oncology.

In addition, women aged older than 65 years who carry BRCA1 and BRCA2 pathogenic variants — as well as PALB2 and CHEK2 — should be considered for MRI screening, researchers noted.

Genetic testing for hereditary cancer.
Data derived from Boddicker NJ, et al. J Clin Oncol. 2021;doi:10.1200/JCO.21.00531.

“Understanding how likely it is that a woman with breast cancer has a genetic predisposition is important in identifying those most in need of testing,” Susan M. Domchek, MD, Basser professor of oncology at Perelman School of Medicine and director of the Basser Center for BRCA at University of Pennsylvania, told Healio. “There has been substantial debate on whether all women with breast cancer should have genetic testing, and now these data help inform this debate.”

Investigators assessed the prevalence of pathogenic variants in breast cancer predisposition genes among 26,707 women aged older than 65 years (mean age, 72.82 years; range, 66-94; 82.6% white; 51.5% with breast cancer) included in population-based studies and estimated their lifetime risk for breast cancer associated with pathogenic variants.

Among the women, 3.18% with breast cancer had a pathogenic variant in a an established breast cancer predisposition gene, compared with 1.48% among those without breast cancer.

Researchers identified pathogenic variants in BRCA1, BRCA2 and PALB2 among 3.42% of women diagnosed with ER-negative breast cancer, 3.01% of women with triple-negative disease and 1% of women with ER-positive disease. Women who had no first-degree relatives with breast cancer had the lowest rate of pathogenic variants.

Researchers reported associations of increased risk for breast cancer with pathogenic variants in CHEK2, PALB2, BRCA2 and BRCA1 (OR = 2.9-4). Women with pathogenic variants in BRCA1, BRCA2 and PALB2 had 15% or higher remaining lifetime risk for breast cancer.

Susan M. Domchek, MD
Susan M. Domchek

“We also demonstrated that if a woman without breast cancer is found to have a BRCA1 or BRCA2 mutation after age 65 years, her chance for developing breast cancer throughout the rest of her life is estimated to be 19% to age 85 years. This can inform decisions on screening and prevention strategies,” Domchek said. “Our study emphasizes that family history and ER status of the tumor are strong predictors for the likelihood of having a mutation in a high-penetrance gene. All women with triple-negative breast cancer should undergo genetic testing.”

Future research will continue to optimize individualized risk for patients, Domchek added.

“In addition, we need to ensure that those at highest risk for BRCA1 and BRCA2 mutations, particularly those with triple-negative breast cancer, undergo genetic testing given the substantial impact this may have on treatment,” Domchek said.

For more information:

Susan M. Domchek, MD, can be reached at University of Pennsylvania, 3400 Spruce St., Philadelphia, PA 19104; email: susan.domchek@uphs.upenn.edu.