Practice-changing use of the 21-gene oncotype DX breast recurrence score test in Latin American hospitals.

Abstract

e12539 Background: The 21-gene test is clinically validated to predict chemotherapy (CT) benefit in node-negative (N0) and node-positive (up to 3 axillary nodes, N+) HR+, HER2− early-stage breast cancer (ESBC). TAILORx showed no CT benefit overall in N0 patients with RS 0-25, but younger patients with RS 16-25 might have some. Clinical guidelines worldwide incorporate the 21-gene test; still, the impact of the test on treatment decisions is unclear in Latin America, where patients often present younger and with more advanced disease. We present a physician survey of the impact of Recurrence Score results on treatment decisions in clinical practice in Latin America. Methods: This multicenter, non-therapeutic, prospective survey enrolled consecutive patients who had 21-gene testing during routine care at 14 community and academic sites in Argentina, Colombia, Mexico, and Peru. Tests were paid for by patients. The physician survey captured patient and tumor characteristics and treatment decisions by physicians pre- and post-assay result. The survey included patients treated before and after TAILORx results reported in 6/2018. Overall net percent change in CT recommendation and 95% Clopper Pearson confidence intervals (CI) were estimated. The proportion with a change between pre-assay treatment recommendation and actual treatment received was calculated overall and by Recurrence Score groups per TAILORx. Results: Between 3/2015 and 12/2019, the survey was completed for 647 patients. 20% had N+ ESBC. Mean patient age was 54 y (24-85 y); 55% were postmenopausal. 17%/63%/20% had grade 1/2/3 tumors; 70%/30% had tumors ≤2/ > 2 cm in size. Recurrence Score results were: 20% RS 0-10, 56% RS 11-25, and 24% RS 26-100. Overall, CT recommendations fell from 325 patients pre-assay to 199 patients post-assay, a 39% decrease (95% CI 33.4 to 44.3) (36% decrease in N0; 46% decrease in N+). The direction of change was consistent with Recurrence Score results. Among N0 patients, the decrease in CT recommendations was 28% (95% CI 18.9 to 39.5) before TAILORx reported and 36% (95% CI 28.4 to 43.7) after. Conclusions: This large survey of 21-gene test practice patterns was the first conducted in Latin America and showed the relevance of 21-gene testing in low- and medium-resource countries to minimize CT over- and underuse in ESBC. Our results showed substantial reductions in CT use overall. After TAILORx, CT use was further reduced, indicating the practice-changing potential of that study.