Genetic Testing for Breast Cancer Patients Expanded

Next-generation sequencing (NGS) allows testing for mutations in additional breast cancer predisposition genes. The frequency of germline mutations detected by using NGS has been reported in patients with breast cancer who were referred for Breast Cancer Early Onset 1 and 2 (BRCA1/2) testing or with triple-negative breast cancer.

The frequency and predictors of mutations in 25 cancer predisposition genes, including BRCA1/2, has been assessed in a sequential series of patients with breast cancer at an academic institution to examine the utility of genetic testing in this population.

A team of scientists led by those at Beth Israel Deaconess Medical Center (Boston, MA, USA) evaluated 488 patients newly diagnosed with breast cancer for mutations in 25 cancer genes at the Dana-Farber Cancer Institute (Boston, MA, USA). Personal and family cancer histories were collected and germline DNA was sequenced with NGS to identify mutations.

The team used the Myriad myRisk Hereditary Cancer test (Myriad Genetic Laboratories; Salt Lake City, UT, USA). The results show that 52 patients, or 10%, had a germline mutation in a breast cancer predisposition gene, including 6.1% in BRCA1/2 (5.1% in non-Ashkenazi Jewish patients). Approximately 30 mutations were in BRCA1/2 genes and 21 were in other cancer genes, representing a 70% increase in mutations identified above BRCA testing alone. Importantly, of the women with deleterious mutations 22, or 42%, were diagnosed after age 45, suggesting that older patients may benefit from genetic testing using the 25-gene panel.

Anne-Renee Hartman, MD, senior vice president of clinical development at Myriad Genetic Laboratories and a co-author of the study said, “This is the first study to show the frequency of germline mutations in BRCA1/2 and other breast cancer predisposition genes in a sequential series of breast cancer patients prospectively collected and unselected for family history or age. Overall, the 25-gene panel identified 70% more breast cancer causing mutations than BRCA1/2 testing alone. This important new finding is being used to identify more patients with mutations with the ultimate goal of helping them and their families to take appropriate risk reduction measures.” The study was published on March 14, 2016, in the Journal of Clinical Oncology.

Related Links:
Beth Israel Deaconess Medical Center
Dana-Farber Cancer Institute
Myriad Genetic Laboratories