Optimum duration of extended adjuvant endocrine therapy in patients with hormone receptor-positive breast cancer: protocol for a network meta-analysis of randomised controlled trials

INTRODUCTION: The type of extended adjuvant endocrine therapy is not clear, nor is the optimum duration of extended adjuvant endocrine therapy for patients with early breast cancer. Our study aims to satisfy the requirements for systematically identifying and synthesising the available evidence on the clinical safety and efficacy of extended adjuvant endocrine therapy for patients with hormone receptor-positive early breast cancer. METHODS AND ANALYSIS: A comprehensive electronic literature database search will be performed using three electronic databases: PubMed, Cochrane Library and Embase (Ovid interface). Our main outcomes of interest were overall survival, disease-free survival, relapse-free survival, invasive contralateral breast cancer, acceptability and grades 3 and 4 non-haematological toxicities in this study. We will assess the risk of bias and overall quality of evidence using the Cochrane Collaboration’s tool and Grades of Recommendation, Assessment, Development and Evaluation, respectively. We will perform subgroup and sensitivity analyses in the selected trials. We will assess the three key assumptions of network meta-analysis: transitivity, consistency and homogeneity. ETHICS AND DISSEMINATION: The protocol was preregistered in the International Prospective Register of Systematic Reviews (PROSPERO) database. Ethics approval and patient consent are not required for the network meta-analysis. The final results of this network meta-analysis will be disseminated through national and international conferences and published in a peer-reviewed journal. PROSPERO REGISTRATION NUMBER: CRD42021278271.