Abstract: Several multi-gene assays have been developed to predict the risk of recurrence in patients with early-stage, estrogen receptor (ER) positive breast cancer. Among them, Oncotype DX 21-gene assay is widely applied among node-negative patients because of its unique prediction of therapeutic benefit. Although many retrospective studies have proved its prognostic and predictive value in node-positive population, evidence from large prospective clinical trials remains insufficient. When combined with clinicopathological variables, the assay has been shown to impact adjuvant treatment decision making in a cost-effective manner. This article reviewed the available clinical evidence for the prognostic and predictive value, unique advantages, the effect on treatment decision making, cost-effectiveness and contradictories of 21-gene assay in early-stage luminal breast cancer patients.

Key words: Breast cancer, Oncotype DX, 21-gene assay, Prognosis, Chemotherapy