Efficacy and tolerability of metronomic chemotherapy in patients with metastatic breast cancer - an international experience in West Sweden and in the South of Ireland

Introduction: Metronomic chemotherapy (MCT) is the continuous administration of low dose chemotherapy. It has significant clinical efficacy with minimal toxicity as compared to conventional chemotherapy regimens. Thus represents an attractive treatment modality in selected patients with advanced breast cancer.

Methods: Patients who received MCT in the form of Capecitabine/Cyclophosphamide for the treatment of advanced breast cancer between May 2014 and October 2018 in Sahlgrenska University Hospital in Sweden and in Cork University Hospital, University Hospital Kerry and the South Infirmary-Victoria University Hospital in Ireland were identified. Medical records were retrospectively reviewed to collect data. All survival analyses were described by Kaplan-Meier curves and analysed with log-rank tests. The primary end-point was time on treatment, used as a surrogate marker for efficacy.

Results: 148 patients were identified (84 - Sweden, 64 - Ireland), with a median age of 64.2 (range 31-89). The overall mean time on treatment for all patients in both countries is 9.05 months (range 0.36 - 67.21). In patients with bone only disease the mean time on treatment was 10.1 months (range 0.7 - 67.2), compared to patients with visceral disease of 8.91 months (range 0.36 - 39.77). Treatment was ended in the majority of patients because of progression of disease, representing 108 patients (72.9%).

Conclusion: This is an observational, retrospective study demonstrating the real world effectiveness of MCT in the treatment of advanced breast cancer. In this cohort of unselected pre-treated patients, the efficacy of MCT was comparable with the survival outcomes of landmark clinical trials.