Does chemotherapy affect survival of breast cancer (BC) patients with recurrence score 26-30?

Abstract

523 Background: The Oncotype-DX recurrence score (RS) allows providers to identify hormone receptor positive and HER2-negative breast cancer (BC) patients that may benefit from adjuvant chemotherapy (AC). The TAILORx Trial showed no benefit of AC among patients with RS of 11-25, except for patients younger than 50 years. There are, however, limited studies examining any benefit of AC among those with RS of 26-30. We sought to examine the effect of AC on BC-specific survival among these patients utilizing a national database. Methods: We queried the Surveillance, Epidemiology, and End Results database for newly diagnosed female BC patients between 2010-2015. We included patients with T1-T3, hormone receptor positive, HER2-negative, and lymph node-negative BC with RS of 26-30. Patients with tumors 5 mm or less and with incomplete records were excluded. Cox Proportional-Hazards Model was done to examine the effect of AC on BC-specific survival. A sub-group analysis was performed for patients younger than 50 years to examine the effect of AC on BC-specific survival. Results: We included 2,982 patients, of whom 1,686 (56.5%) received AC. Administration of AC was associated with lower age (56.5 [9.2] vs 61.8 [9.7], p < 0.001), Grade III&IV (39.7% vs 30.2%, p < 0.001), married or patients with partners (66.5% vs 61.5%, p < 0.001), and T stage > 1 (31.3% vs 26.8%, p = 0.03). AC was not associated with insurance status, race, and histology. Overall 5-year BC-specific survival was 97.3% (96.2-98.3%). After adjustment through cox regression, AC was found to not have an effect on survival (HR: 0.54 [0.27-1.10], p = 0.09). There were 579 (19.4%) patients that were younger than 50 years, and AC did not have an effect on survival among these patients (HR: 0.44 [0.08-2.44], p = 0.35). Similarly, among the 2,403 (80.6%) patients aged 50 or older, AC did not have an effect on survival (HR: 0.49 [0.22-1.11], p = 0.09). Conclusions: In this retrospective analysis, administration of AC was associated with lower age, higher grade, marital status, and T stage. AC did not affect BC-specific survival among patients with a RS of 26-30. Subgroup analysis did not show any benefit of AC among patients younger than 50 years or among those 50 or older. Further prospective randomized trials are warranted to identify sub-groups that may potentially benefit from AC.