Impact of TAILORx on chemotherapy prescribing and 21-gene recurrence score–guided treatment costs in a population-based cohort of patients with breast cancer

Abstract

Background: The trial assigning individualized options for treatment (Rx) (TAILORx) confirmed the predictive value of the 21-gene recurrence score (RS) assay in hormone receptor (HR)–positive, HER2-negative, node-negative breast cancer and established thresholds for chemotherapy benefit in younger and older patients. Real-world chemotherapy use and RS-guided treatment costs in British Columbia post-TAILORx were examined. Methods: The authors assembled 3 cohorts of HR-positive, HER2-negative, node-negative patients with breast cancer defined by diagnosis: before RS funding (cohort 1 [C1]: January 2013-December 2013), after introduction of public RS funding (cohort 2 [C2]: July 2015-June 2016), and after TAILORx results (cohort 3 [C3]: July 2018-June 2019). Chemotherapy use was compared between cohorts by age and RS. Budgetary impacts of RS testing on chemotherapy costs were evaluated pre- and post-TAILORx. Results: Among the 2066 patients included, chemotherapy use declined by 19% after RS funding was introduced and by an additional 23% after TAILORx publication (P =.001). Reduction in chemotherapy use was significant for RS 11-20 tumors (C3 vs C2, P =.004). There was no significant change in chemotherapy use in patients >50 years old (C2:12% vs C3:10%, P =.22). RS testing was associated with higher cost savings post-TAILORx, except in patients 70 to 80 years old, where testing led to excess costs when adjusting for the low rate of RS-concordant chemotherapy prescribed. Conclusions: TAILORx has had population-based impacts on chemotherapy prescribing in intermediate RS tumors and patients ≤50 years old. The lower clinical use of RS and increased spending in patients 70-80 years old highlights the importance of careful selection of older candidates for high-cost genomic testing. Lay Summary: The 21-gene recurrence score (RS) test helps predict whether patients with hormone-positive, HER2-negative, lymph node-negative breast cancer are likely to benefit from chemotherapy. The recent trial assigning individualized options for treatment (Rx) (TAILORx) found that patients with intermediate RS tumors did not benefit from chemotherapy. The authors assessed whether TAILORx results translated to real-world changes in chemotherapy prescribing patterns. In this study, chemotherapy use decreased by 23% after TAILORx, with the greatest reductions seen among intermediate RS tumors and younger patients. In contrast, RS testing had lower clinical value and increased treatment costs in elderly patients, which requires further study to ensure optimal care for this age group.