The value of liquid biopsy in the diagnosis and staging of hepatocellular carcinoma: A systematic review

Background: Blood-borne tumour markers in the form of circulating tumour cells (CTCs) are of intense research interest in the diagnostic and prognostic work-up of hepatocellular carcinoma (HCC). Methods: This is a meta-analysis. Using a PICO strategy, adults with HCC was the population, with the individual CTCs as the intervention and comparators. The primary outcome was the sensitivity and specificity of HCC detection with tumour specific single gene methylation alteration. Secondary outcomes were the comparison using specific assay methods and the effect of early vs. late stages on CTC positivity. We included patients with HCC who had samples taken from peripheral blood and had sufficient data to assess the outcome data. ASSIA, Cochrane library, EMbase, Medline, PubMed and the knowledge network Scotland were systematically searched with appropriate Mesh terms employed. The quality assessment of diagnostic accuracy studies (QUADAS) was used to ensure quality of data. Statistical analysis was performed using the 'Rev Man' meta-analysis soft ward for Windows. Results: The review included 36 studies, with a total of 5,853 patients. Here, we found that AFP has the highest overall diagnostic performance. The average Youden index amongst all CTC was 0.46 with a mode and median of 0.5 with highest of 0.87 and lowest of 0.01. Conclusions: The available literature provides weak evidence that there is potential in the use of CTC, however the lack of a standardised procedure in the study of CTC contribute to the lack of consensus of use. Future research should include large scaled, standardized studies for the diagnostic accuracy of CTCs.