Expression of estrogen receptor beta and overall survival in non-small cell lung cancer patients: Protocol for a systematic review and meta-analysis of cohort studies

BACKGROUND: Lung cancer is the leading cause of cancer-related deaths among males and the second leading cause among females worldwide. Numerous studies have linked estrogen status to lung cancer outcome. However, there are studies with conflicting results about the effect of ERβ on survival of lung cancer. The aim of this meta-analysis is to evaluate the prognostic impact of estrogen receptor beta expression on survival among NSCLC patients. METHODS: We will search 15 electronic databases, including PubMed, Web of Science, EMBASE, Cochrane Library, and CNKI from inception to June 1, 2019. We will include all cohort studies comparing overall survival of NSCLC patients with high or low estrogen receptor beta expression. The database searches will be supplemented by searching through citations and references. Two reviewers will independently screen search results to identify eligible articles, complete data collection, and conduct quality assessment. All disagreements will be resolved by an independent third reviewer. Methodological quality of the included studies will be assessed using the Newcastle- Ottawa scale. Discrepancies will be resolved by consensus or by consulting a third author. Meta-analyses will be performed, and findings will be reported according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) and the meta-analysis of observational studies in epidemiology (MOOSE) guidelines. RESULTS: The results will be submitted to a peer-reviewed journal for publication. CONCLUSION: This review will provide a comprehensive evaluation of the evidence on the prognostic impact of ERβ expression among NSCLC patients and will help clinicians find potential treatments based on estrogen signaling.