Optimal interval to surgery after chemoradiotherapy in rectal cancer: A protocol for systematic review and network meta-analysis

BACKGROUND: Rectal cancer is the second leading cause of cancer-related death in the Western world. Preoperative neoadjuvant chemoradiotherapy (nCRT) has been widely performed in the treatment of rectal cancer patients. However, there is no consensus on the length of waiting interval between the end of preoperative nCRT and surgery. Present network meta-analysis (NMA) aims to compare the differences of effect between all available interval to surgery after nCRT in rectal cancer in improving overall survival, disease-free survival and pathologic complete response (pCR) rate, and to rate the certainty of evidence from present NMA. METHOD: We will systematically search PubMed, EMBASE, Chinese Biomedical Literature Database, and Cochrane Central Register of Controlled Trials (CENTRAL) databases to identify studies assessing the interval to surgery after CRT in rectal cancer. We will conduct this systematic review and meta-analysis using Bayesian method and report the full-text according to Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) Extension Vision statement (PRISMA-NMA). We will assess the risk of bias of individual study using the Newcastle–Ottawa Scale and Cochrane Handbook V.5.1.0. We will also use the advance of GRADE to rate the certainty of NMA. Data will be analyzed by using R software V.3.4.1. RESULTS: The results of this study will be published in a peer-reviewed journal. CONCLUSION: To the best of our knowledge, this systematic review and NMA will first use both direct and indirect evidence to compare the differences of all available interval to surgery after CRT in rectal cancer. This is a protocol of systematic review and meta-analysis, so the ethical approval and patient consent are not required.