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. The primary objective was to characterize how the results of the RS assay affected physicians’ recommendations for adjuvant chemotherapy. Secondary objectives were to characterize changes in the physicians’ and patients’ level of confidence in treatment recommendations, to determine whether the results of the RS assay affected patients’ treatment preferences, and to determine the final treatment administered. Results Seventy‐two patients were recruited; the mean age was 61. RS was