Prospective Evaluation of the Impact of the 21-Gene Recurrence Score Assay on Adjuvant Treatment Decisions for Women with Node-Positive Breast Cancer in Ontario, Canada.

Background: The 21-gene Recurrence Score (RS) assay is only reimbursed in Ontario for node-negative and micrometastatic node-positive (N+) early-stage breast cancer (EBC). We carried out a prospective study to evaluate the impact of the assay on treatment decisions for women with N+ EBC.

Subjects, Materials, And Methods: Women with estrogen receptor-positive, human epidermal growth receptor 2-negative EBC and one to three positive axillary lymph nodes, who were candidates for adjuvant chemotherapy in addition to hormonal treatment, but in whom the benefit of chemotherapy was uncertain, were eligible.