Short-chain fatty acid concentrations in the incidence and risk-stratification of colorectal cancer: a systematic review and meta-analysis

Abstract

AbstractThe beneficial role of gut microbiota and bacterial metabolites, including short-chain fatty acids (SCFAs), is well recognized; although the available literature around their role in colorectal cancer (CRC) has been inconsistent.We performed a systematic review and meta-analysis to examine associations of fecal SCFA concentrations to the incidence and risk of CRC.Data extraction through Medline, Embase, and Web of Science was carried out from database conception to May 21, 2021. Predefined criteria included human clinical observational studies, while excluding cell/animal model studies, conference proceedings, and reviews. Quality assessment of selected 16 case-control and six cross-sectional studies is reported using PRISMA 2020 guidelines. Studies were categorized for CRC risk or incidence, and RevMan 5.4 was used to perform the meta-analyses. Standardized mean differences (SMD) with 95% confidence intervals (CI) were calculated using a random-effects model.Combined analysis of acetic-, propionic-, and butyric-acid revealed significantly lower concentrations of these SCFAs in individuals with high-risk of CRC (SMD = 2.02, 95% CI 0.31 to 3.74, P = 0.02). Further, CRC incidence increased in individuals with lower levels of SCFAs (SMD = 0.45, 95% CI 0.19 to 0.72, P = 0.0009), compared to healthy individuals.Overall, lower fecal concentrations of the three major SCFAs is associated with higher risk and incidence of CRC.