Mayo Clinic researchers recommend all women under 66 with breast cancer diagnosis be offered genetic testing

A study by Mayo Clinic researchers suggests that all women under the age of 66 with a breast cancer diagnosis be offered germline genetic testing to determine if they have a gene mutation known to increase the risk of developing other cancers and cancers among blood relatives. Current guidelines from the National Comprehensive Cancer Network (NCCN) recommend germline testing for all women diagnosed with breast cancer under the age of 46 regardless of family history and breast cancer subtype.

“There is considerable confusion about the best method for selecting who may benefit from hereditary cancer genetic testing from among all women diagnosed with breast cancer,” says Fergus Couch, Ph.D. (PATH ’97), chair, Division of Experimental Pathology and Laboratory Medicine at Mayo Clinic in Rochester. “The NCCN has very specific guidelines for who may benefit from genetic testing based on the age of diagnosis and family history of certain cancers, while the American Society of Breast Surgeons (ASBrS) recommends testing all women with breast cancer.”

Dr. Couch and his colleagues evaluated all know breast cancer predisposition genes in a Mayo Clinic breast cancer registry and showed that NCCN guidelines overlooked approximately 30% of patients with genetic mutations known to increase the risk of developing breast cancer.

Based on this information, Dr. Couch and his colleagues recommend increasing the age for genetic testing to all women diagnosed with breast cancer under age 66 regardless of family history of cancer. “This change would help identify 98% of women with BRCA1 and BRCA2 mutations, and more than 90% of women with mutations in other predisposition genes, while avoiding testing of 20% of all breast cancers.” He says this approach also may result in a reduced burden on the genetic services needed for women receiving testing.