A new study indicates that most women with breast cancer diagnosed over 65 should be offered hereditary cancer genetic testing. The study appeared in the Journal of Clinical Oncology.
Dr. Couch says that women over 65 rarely qualify for hereditary cancer genetic testing based on current testing guidelines because they are thought to exhibit low rates of genetic mutations in breast cancer genes.
“Most studies of breast cancer genes have not looked at older women, those who were diagnosed over the age of 65,” said lead researcher Fergus Couch, Ph.D., of Mayo Clinic Cancer Center via a press release. Dr. Couch added that these studies have mainly tested women with a strong family history of breast or ovarian cancer rather than those in the general breast cancer population. “We were not sure what this study of the older breast cancer population would yield, but our results support broader testing, regardless of age or family history,” says Dr. Couch.
To conduct this study, researchers assessed women with breast cancer diagnosed after 65 and matched the cohort with unaffected women from a large population in the CARRIERS study. “We found that mutations in actionable breast cancer risk genes were present in 3.2% of the women with breast cancer,” says Dr. Couch.
In high-risk breast cancer genes, including BRCA1, BRCA2 and PALB2, the researchers observed that 1.35% of women with breast cancer showed mutations and that more than 2.5% of women with estrogen receptor-negative breast cancer had high-risk mutations, regardless of their age. “As 2.5% mutation frequency is often used to trigger genetic testing, these results suggest that all women with estrogen receptor-negative breast cancer and perhaps all women with breast cancer, including those diagnosed over age 65 should be offered hereditary breast cancer testing,” says Dr. Couch, who also noted that women over 65 with high-risk mutations may benefit from targeted therapies and improved risk assessment for secondary breast cancers.