Circulating Extracellular Vesicle Biomarkers as Diagnostic and Prognostic Biomarkers of Liver Metastasis in...

Liver metastasis adversely affects prognosis in colorectal cancer (CRC). Biomarkers are needed for both detection of liver metastasis and accurate prognostication for patients who have colorectal cancer with liver metastasis (CRLM). Circulating extracellular vesicles (EVs) are a potential source of minimally invasive biomarkers. This study aimed to review circulating EV biomarkers associated with liver metastasis in patients who have CRC and prognostic outcomes for patients with CRLM.

Studies investigating circulating EV biomarkers in adult patients with CRLM were included for analysis. Journal articles and conference abstracts in English of any study design and from any publication date were included. A systematic search across Medline, Embase, and Web of Science was performed. The QUIPS tool and/or QUADAS-2 tools were used to assess risk of bias.

An initial search identified 5187 studies, with 29 studies meeting the inclusion criteria. Of these 29 studies, 6 reported prognostic biomarkers, 21 reported diagnostic biomarkers, and 2 reported both. The eight studies reporting prognostic biomarkers included a total of 1309 patients and identified 13 biomarker candidates. The 23 studies that reported on diagnostic biomarkers included 574 CRLM patients and identified 40 biomarker candidates. Several biomarkers, including PD-L1 and TIMP-1, were highly predictive of overall survival. Most of the biomarkers were identified in a single study only.

Circulating EVs are a promising biomarker source in CRLM. However, with only limited studies to date, further research is needed to substantiate these findings.