Treatment-associated survival outcomes in real-world patients with de novo metastatic triple-negative breast cancer: Age as a significant treatment effect-modifier

Abstract

Evidence for optimizing the first-line chemotherapy for patients with metastatic triple-negative breast cancer (mTNBC) is lacking. This study assessed the utilization patterns of chemotherapy and associated survival outcomes in de novo mTNBC patients. Taiwan's cancer registry was utilized to extract study patients with newly-diagnosed breast cancer during 2011-2015 and confirmed metastatic triple-negative status. The patients' medical records (e.g., diseases, treatments) and death status were obtained from the National Health Insurance Research Database. Utilization of first-line chemotherapy regimens was analyzed and associated survival outcomes were assessed using Cox models. 93.60% of the mTNBC patients (n=297) received chemotherapy, where combination regimens (75.54%) were more common than single-agent regimens (24.46%) in the first-line setting. A non-statistically lower all-cause death associated with combination versus single-agent chemotherapy (hazard ratio: 0.830 [0.589, 1.168]) was observed. Age was identified as a significant effect-modifier in treatment-associated survival outcomes (p=0.008); younger patients (aged<40 and 40-59 years) versus older patients (aged≥60 years) had a lower all-cause mortality when receiving combination versus single-agent chemotherapy. A lower all-cause mortality associated with taxane- versus non-taxane-based therapy was revealed among those on single-agent chemotherapy (hazard ratio: 0.557 [0.311, 0.999]). Generally, single-agent and combination chemotherapies yielded comparable survival outcomes as the first-line treatment for de novo mTNBC. Younger patients may benefit more from combination regimens, in terms of better survival outcomes. Single-agent chemotherapy may be preferable as the first-line choice for elderly patients who are vulnerable to the toxicity of multiple chemotherapy agents.