Genomic Testing in the Management of Early-Stage Breast Cancer.

OBJECTIVES: To describe common genomic tests being used clinically to assess prognosis and guide adjuvant chemotherapy and endocrine therapy decisions for early-stage breast cancer.
METHODS: Case presentation and review of the literature.
RESULTS: Hormone receptor-positive (HR-positive) breast cancers, which express the estrogen and/or progesterone receptor, account for the majority of breast cancers. Endocrine therapy can be highly effective for patients with these HR-positive tumors, and identification of HR-positive breast cancers that do not require the addition of chemotherapy is critical. Clinicopathological features of the breast cancer, including tumor size, nodal involvement, grading, and HR status, are insufficient in predicting the risk for recurrence or the need for chemotherapy. Furthermore, a portion of HR-positive breast cancers have an ongoing risk for late recurrence, and longer durations of endocrine therapy are being used to reduce this risk.
CONCLUSION: There is sufficient evidence for use of genomic testing in early-stage HR-positive breast cancer to aid in chemotherapy recommendations. Further confirmation of genomic assays for prediction of benefit from prolonged endocrine therapy is needed.