Background: Human epididymis protein 4 (HE4) protein has garnered a great degree of interest as a complementary biomarker to carbohydrate antigen 125 (CA125), or even as an independent biomarker for monitoring, diagnosis, and prognostication of ovarian cancer. Its use is currently limited to ovarian cancer. Recent studies have suggested that it could also be used in other types of cancers.
Methods: The Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) guidelines was used to design this meta-analysis protocol. The final study will also be conducted under the PRISMA guidelines for systematic reviews and meta-analyses. The core bibliographic database search will be carried out by 2 reviewers working individually, with each conducting an initial screening based on titles and abstracts. The shortlisted articles will be selected for review and statistical analysis based on predefined inclusion and exclusion criteria. Study characteristics, relevant clinicopathological characteristics and statistical data required for meta-analysis (hazard ratios [HRs] and 95% confidence interval [CIs) will be extracted and compiled into a MS Excel datasheet. Meta-analysis will be performed, using a random-effects model, and the results (pooled HR and 95% CI) will be presented in the form of a forest plot. Publication bias will also be assessed by use of Egger bias indicator test and funnel plot symmetry. If data are insufficient, a narrative line of review will be pursued.
Discussion: HE4 protein has been shown to have great potential for clinical use as a diagnostic and prognostic marker in epithelial ovarian cancer (EOC). However, HE4 is not only limited to expression in ovarian cancer, but is also overexpressed in lung and endometrial cancers. The effectiveness of HE4 as a biomarker in cancers (other than EOC) has not yet been studied in the form of a comprehensive systematic review and meta-analysis. The results of this study should allow for expanded use of HE4 as a multiutility biomarker in multiple cancer types, thereby, elevating HE4's value as a cancer biomarker.