Patient-Reported Outcome Results from the Open-Label Randomized Phase III SELECT BC Trial Evaluating First-Line S-1 Therapy for Metastatic Breast Cancer

Objective: To evaluate the effects of S-1, an orally administered 5-FU agent, versus taxane on patient-reported outcomes (PROs) in the SELECT BC trial. Methods: Patients with HER2-negative and endocrine treatment-resistant breast cancer with metastasis or recurrence after surgery were randomly assigned to receive first-line taxane or S-1. PROs (secondary endpoint) were assessed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) and Patient Neurotoxicity Questionnaire (PNQ) at baseline and at 3, 6, and 12 months. We conducted a responder analysis for the QLQ-C30 and PNQ and created cumulative distribution function (CDF) plots as a sensitivity analysis. Results: The questionnaire response rates were over 80% from 386 patients, who completed at least one baseline questionnaire. S-1 was significantly superior to taxane with respect to 6 scales (physical functioning [p = 0.03], role functioning [p = 0.04], social functioning [p < 0.01], financial difficulties [p = 0.01], global health status [p = 0.02], and constipation [p < 0.01]) and sensory neuropathy (p = 0.01). The CDF plots partially supported the conclusions and their robustness. Conclusion: First-line S-1 therapy has clinical benefits with respect to many aspects of health-related quality of life for metastatic breast cancer patients.