Researchers at Stanford Medicine have found that postmenopausal women with breast cancer are just as likely as Ashkenazi Jewish women to carry specific inherited breast cancer mutations. Performing genetic testing on these patients could inform treatment decisions, according to the study.

Current guidelines recommend that Ashkenazi Jewish women discuss their cancer risk with physicians to determine whether genetic testing is warranted. However, other women with breast cancer are less likely to receive a recommendation of testing, according to the study authors.

When determining whether to recommend genetic testing, physicians typically consider a woman’s age at diagnosis and her family’s cancer history. Currently, most guidelines do not recommend testing postmenopausal women with breast cancer if there are no risk factors, but the new study’s findings could change those practices.

The study authors noted that identifying inherited cancer-associated mutations, particularly in the BRCA1 and BRCA2 genes, is vital because some mutations can increase the risk of other cancers, including ovarian cancer.

“There’s been a lot of controversy in the field as to whether every woman with breast cancer should receive genetic testing, in part because we didn’t know how prevalent cancer-associated mutations are in this largest subgroup of newly diagnosed people—that is, women who develop breast cancer after menopause without the presence of any known hereditary factors,” said lead study author Allison Kurian, MD, MSc, in a statement.

The researchers aimed to compare the prevalence of cancer-associated mutations in 10 breast-cancer risk genes, including BRCA1 and BRCA2. They compared 2322 women without breast cancer with 2195 participants who were diagnosed with breast cancer at an average age of 73. The data were obtained from the Women’s Health Initiative, which enrolled more than 160,000 women in the United States between 1993 and 1998.

In the study, approximately 3.5% of the women with breast cancer had a cancer-associated mutation in at least 1 of the 10 genes, compared with approximately 1.3% of women without cancer. When the focus was limited to just the BRCA1 and BRCA2 genes in women diagnosed before age 65, the researchers found that approximately 2.2% of women with breast cancer had mutations, compared with approximately 1.1% of those without breast cancer.

The authors noted that only approximately 31% of women with cancer and 20% of women without cancer, both with BRCA1 or BRCA2 mutations, were likely to have been recommended for testing under the current guidelines of the National Comprehensive Cancer Network.

These findings are the first to suggest that newly diagnosed postmenopausal women with breast cancer but no hereditary risk factors may still benefit from genetic testing for inherited cancer-associated mutations, according to the study authors.

“Now we know that the prevalence of cancer-associated BRCA1 and BRCA2 mutations in women diagnosed with breast cancer after menopause rivals that in women of Ashkenazi Jewish descent—a population that is currently encouraged to discuss genetic testing with their doctors,” Kurian said. “We finally have a read on the likely benefit of testing this most common subgroup of breast cancer patients.”

REFERENCE
Older women with breast cancer may benefit from genetic testing [news release]. Stanford Medicine; March 10, 2020. http://med.stanford.edu/news/all-news/2020/03/older-women-with-breast-cancer-may-benefit-from-genetic-testing.html. Accessed March 23, 2020.