Study: BRCA Mutations More Common in Older Women Diagnosed with Breast Cancer

Approximately 1 in 40 postmenopausal women diagnosed with breast cancer before the age of 65 had a mutation linked to cancer in the BRCA1 or BRCA2 gene, according to an analysis of data from the Women’s Health Initiative (WHI).

This finding suggests that genetic testing may be beneficial for postmenopausal women who are newly diagnosed with breast cancer even if they don’t have risk factors for inheriting a mutation linked to breast cancer, according to the study authors.

Researchers at Stanford University looked at data from 4517 women who were a part of the WHI trial. This included information from more than 161,608 postmenopausal women who were aged 50 to 79 years when they joined the trial between 1993 and 1998.

None of the women in the analysis had been diagnosed with breast cancer when they joined the WHI, according to the researchers. Further, 2195 were diagnosed with breast cancer during the WHI and 2322 had not been diagnosed with breast cancer as of September 20, 2017, according to the study authors.

Out of the women diagnosed with breast cancer, half were older than the age of 73 when they were diagnosed and the other half were younger. Approximately 66% of these participants were white.

In comparison, out of the women who were not diagnosed with breast cancer, half of the women were older than age 81 at the last follow-up, and the other half were younger. Approximately 84.9% of these participants were white.

All of the women were genetically tested using a Myriad Genetics test that looked for mutations in a panel of 28 genes, including BRCA1, BRCA2, ATM, BARD1, CDHI1, CHEK2, NBN, PALB2, STK11, and TP53.

Harmful mutations were found in 241 women, including 148 who had been diagnosed with breast cancer and 93 who had not been diagnosed with breast cancer, according to the researchers. Specifically, in harmful mutations in the BRCA1 or BRCA2 genes, 2.21% of women diagnosed with breast cancer when they were younger than 65 had a BRCA1 or BRCA2 mutation. Meanwhile, 1.09% of women diagnosed with breast cancer when they were the age of 65 and older had a BRCA1 or BRCA2 mutation.

Out of the women who had a harmful mutation in another breast cancer-associated gene, 34% who were diagnosed with breast cancer met National Comprehensive Cancer Network (NCCN) genetic testing guidelines, whereas 16% of women who had not been diagnosed with breast cancer met NCCN genetic testing guidelines.

This is the first study to suggest that postmenopausal women newly diagnosed with breast cancer who do not have any risk factors for inheriting a mutation linked to breast cancer may benefit from genetic testing, according to the researchers.

“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 risk factors," said lead study author Allison Kurian, MD, associate professor of medicine and of epidemiology and population health at Stanford, in a press release.

REFERENCE

BRCA mutations more common than thought in older women diagnosed with breast cancer. Breastcancer.org. https://www.breastcancer.org/research-news/brca-mutations-more-common-in-older-dx-women. Published March 18, 2020. Accessed April 13, 2020.