The value of biomarkers in colorectal cancer: Protocol for an overview and a secondary analysis of systematic reviews of diagnostic test accuracy

BACKGROUND: Colorectal cancer (CRC) is the third most common cancer in the world, with 694,000 deaths each year. Despite improvements in treatment strategies in recent years, the overall survival rate of CRC is still very low and the survival rate is highly dependent on the stage at the time of diagnosis. Some biomarkers have shown great potential for early screening of CRC and some have been tested in systematic reviews (SRs). However, the quality of these SRs remains unclear and these SRs did not clarify which biomarker is the optimal diagnostic test. This overview will evaluate the methodological quality of available SRs and compare the diagnostic value of different biomarkers in order to find the best biomarker for diagnosing CRC. METHODS: A comprehensive literature search for SRs published before February 2019 was conducted in the PubMed, Embase.com, Cochrane Library, and Web of Science without any language restrictions. We will use the assessment of multiple systematic reviews-2 instrument to assess the methodological quality of each SR. Bubble plots will be used to summarize the main characteristics and quality of SRs. Standard pairwise meta-analysis and adjusted indirect comparison will be conducted to compare the diagnostic value of different biomarkers. RESULTS: The results of this overview will be submitted to a peer-reviewed journal for publication. CONCLUSION: The findings of this project will provide a general overview and evidence of the diagnostic value of biomarkers in detecting CRC. PROSPERO REGISTRATION NUMBER: CRD42019125880.