Association of change in health-related quality of life and treatment discontinuation in metastatic breast cancer: a post hoc, exploratory analysis of two randomized clinical trials

PURPOSE: Identifying factors associated with treatment alteration (treatment discontinuation and dose reduction) may help to attain the treatment goals for metastatic breast cancer. The value of changes in the quality of life (QOL) in predicting treatment alteration remained unclear. This study aimed to examine the relationship between changes in the QOL and treatment alteration of first-line chemotherapy for metastatic breast cancer. METHODS: We merged data from two randomized clinical trials in Japan, conducted from 2006 to 2017, that included patients who were diagnosed with human epidermal growth factor receptor 2-negative and endocrine treatment-resistant breast cancer, with metastatic disease at presentation or recurrence after surgery. The European Organisation for the Research and Treatment of Cancer Quality of Life Questionnaire Core 30 was used to assess QOL. The association between change in time-dependent QOL (worsening by 10-point or not) and time to treatment alteration was assessed using the Cox regression models controlling for patient characteristics (age, liver metastasis, hormone status, and treatment regimen) and baseline QOL. RESULTS: Worsening physical functioning, global health status, and dyspnea were significantly associated with treatment discontinuation. Worsening role functioning, global health status, and fatigue were significantly associated with dose reduction. The threshold for defining worsening did not have a significant impact on the relationship. CONCLUSION: Changes in QOL are associated with the probability of treatment alteration among metastatic breast cancer patients. Physical functioning, role functioning, global health status, dyspnea, and fatigue should be prioritized for symptom management in patients with metastatic breast cancer. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00520-022-07283-0.