Breast Cancer Assay Can Guide Adjuvant Therapy Decisions

To assess a patient's risk for breast cancer returning or whether adjuvant therapy would be beneficial, a breast cancer assay can provide important biological information to determine the best course of treatment.

Biological differences between BRCA-associated and sporadic breast cancer could warrant different recommendations for adjuvant therapies among patients with phenotypically similar cancers. Research scientists used Oncotype DX, a 21-gene breast cancer assay, to quantify predicted benefit of adjuvant therapy to guide clinical decisions in patients with early-stage, hormone receptor-positive breast cancer.

Payal Deepak Shah, MD, from Memorial Sloan Kettering Cancer Center (MSKCC), and colleagues reviewed medical records of patients with germline BRCA1 and BRCA2 (gB) mutations who were identified and matched 1:2, based on age at diagnosis and tumor size. In other words, 50 cases (patients with mutations) and 100 controls (patients without mutations) were included.

Dr. Shah presented their findings in a poster session (abstract 519) at the 2015 American Society of Clinical Oncology (ASCO) Annual Meeting, held May 29-June 2, 2015 in Chicago. The findings can also be found in the May 2015 online issue of the Journal of Clinical Oncology.

What the researchers found in the 150 records they reviewed was that the presence of a gB1/2 mutation may be a biomarker for less favorable outcomes in patients with early-stage, hormone receptor-positive breast cancers. Many affected gB carriers have recurrence scores indicating clear benefit from adjuvant therapy. The researchers concluded that increased use of adjuvant therapy in gB carriers may mitigate otherwise unfavorable outcomes, accounting for the similar prognoses for carriers and noncarriers of the mutation.

What's more is that genomic tests like this may not only predict benefit of adjuvant therapy, but also the likelihood of recurrence. This may help to protect patients in the future from overtreatment, resulting in a huge plus for patients and their families.