Fibroblast Activation Protein Overexpression in Gastrointestinal Tumors: Protocol for a Systematic Review and Meta-analysis

BackgroundA hallmark of gastrointestinal cancer, especially pancreatic cancer, is the dense stromal tumor microenvironment in which cancer-associated fibroblasts (CAFs) represent the major stromal cell type. Preclinical studies have demonstrated that depletion of fibroblast activation protein (FAP)–positive CAFs results in increased survival. ObjectiveWe present the protocol for a systematic review and meta-analysis that aim to assess the currently available evidence on the effect of FAP expression on survival and clinical characteristics in gastrointestinal cancers. MethodsThe literature search and data analysis will be conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2020 statement. The databases PubMed/MEDLINE, Web of Science Core Collection, Cochrane Library, and ClinicalTrials.gov will be searched via their respective online search engines. A meta-analysis comparing patients with and without FAP overexpression with the following outcomes will be performed: postoperative survival (overall and median survival; 1-, 2-, 3-, and 5-year survival rates), histological differentiation (grading), local tumor invasion, lymph node metastases, and distant metastases. Odds ratios will be calculated for binary data, and weighted mean differences and relative SD differences will be determined for continuous data. The 95% CI, heterogeneity measures, and statistical significance will be reported for each outcome. The chi-square and Kruskal-Wallis tests will be used to evaluate statistical significance. A P value of