Background: The development of multigene assays has proved useful in the clinical management of early-stage breast cancer. The 21-gene recurrence score (RS) assay has been shown to quantify risk of distant recurrence and predict chemotherapy benefit in node-negative and node-positive, estrogen-receptor (ER)-positive breast cancer patients. Small, single-institution series have shown that, compared with standard clinicopathologic criteria, use of RS significantly affects adjuvant chemotherapy recommendations.
Methods: We performed a retrospective review of RS use and its effect on chemotherapy recommendations in node-negative, ER-positive breast cancer patients at a tertiary care teaching hospital. Patient and tumor characteristics and adjuvant treatment information were obtained on 183 patients with RS results between January 2004 and October 2009. Risk categories were assigned based on the RS and on standard clinicopathologic criteria according to guidelines from NCCN, St. Gallen, and Adjuvant!.
Results: A total of 14 patients were excluded for negative ER status (n=2), insufficient data (n=4), inclusion in TAILORx trial (n=7), and recurrent breast cancer (n=1), leaving 169 patients in the cohort. RS use increased 3-fold over the study period (from 18% in 2004 to 50% in 2009). Tumor grade, ER status, and PR status were significantly correlated with RS category. Overall concordance between RS and NCCN, St. Gallen, and Adjuvant! was 10, 48, and 50%, respectively. Depending on the guideline used for comparison, adjuvant therapy recommendations changed with the addition of the RS in 27-74% of cases.
Conclusions: RS use is increasing, and the assay significantly reduced adjuvant chemotherapy utilization in node-negative, ER -positive breast cancer patients.