Ten-year clinical outcomes in N0 ER+ breast cancer patients with Recurrence Score-guided therapy

The 21-gene Recurrence Score (RS) assay is a validated prognosticator/predictor of chemotherapy (CT) benefit in early-stage estrogen receptor (ER)-positive breast cancer (BC). Long-term data from real-life clinical practice where treatment was guided by the RS result are lacking. We performed exploratory analysis of the Clalit Health Services (CHS) registry, which included all CHS patients with node-negative ER+ HER2-negative BC who underwent RS testing between 1/2006 and 12/2009 to determine 10-year Kaplan–Meier estimates for distant recurrence/BC-specific mortality (BCSM) in this cohort. The analysis included 1365 patients. Distribution of RS results: RS 0–10, 17.8%; RS 11–25, 62.5%; RS 26–100, 19.7%. Corresponding CT use: 0, 9.4, and 69.9%. Ten-year distant recurrence rates in patients with RS 0–10, 11–25, and 26–100: 2.6% (95% confidence interval [CI], 1.1–6.2%), 6.1% (95% CI, 4.4–8.6%), and 13.1% (95% CI, 9.4–18.3%), respectively ( P