Comparative Effectiveness of Palliative Chemotherapy in Metastatic Breast Cancer: A Real-World Evidence Analysis

Abstract

Abstract Background In the absence of randomized controlled trials, real-world evidence may aid practitioners in optimizing the selection of therapy for patients with cancer. The study's aim was to determine real-word use, as well as compare effectiveness, of single-agent and combination chemotherapy as palliative treatment for female patients with metastatic breast cancer (mBC). Materials and Methods Using administrative claims data from the Symphony Health's Integrated Oncology Dataverse, female patients with mBC treated with at least one chemotherapy-only treatment (COT) between January 1, 2013, and December 31, 2017 were selected. The frequency of use of single-agent versus combination chemotherapy overall and by line of therapy (LOT) was calculated whereas effectiveness was measured using time to next treatment (TNT). Results A total of 12,381 patients with mBC were identified, and 3,777 (31%) received at least one line of COT. Of the 5,586 observed LOTs among the 3,777 patients, 66.5% were single-agent and 33.5% combination chemotherapy. Combination chemotherapy was most frequently used in first-line (45%) and least frequently in fifth-line (16%). Across all LOTs, median TNT was significantly longer for single-agent versus combination chemotherapy (5.3 months vs. 4.1 months, p < .0001). Comparison of median TNT by LOT showed significance in third-line and greater but not in first-line or second-line. Among single agents, the median TNT for patients receiving capecitabine was longest in comparison to all other single agents. Conclusions The frequency of combination COT use, particularly in first-line, warrants further research given published guideline recommendations. The observed TNT difference favoring single-agent treatment in later lines supports guideline recommendations. Variance between single-agent preference and observed TNT was noteworthy.