METHODS: The present systematic review and meta-analysis was conducted to estimate the prevalence of G. duodenalis and respective odds ratios (ORs) in cancer patients around the globe. Four online databases-PubMed, Scopus, Web of Science and Google Scholar-were carefully explored for relevant literature without time limitation until 28 November 2020. Meta-analysis was done based on a random effects model to pool the estimations and define 95% confidence intervals (CIs).

RESULTS: The overall weighted prevalence of G. duodenalis infection in cancer patients was calculated to be 6.9% (95% CI 0.5 to 9.3) globally, based on data from 32 studies. Although not statistically significant, eight case-control studies revealed that cancer patients were 1.24 times (95% CI 0.66 to 2.31; p=0.501) more exposed to G. duodenalis infection than healthy controls. Moreover, the prevalence of infection was not significantly associated with quantitative variables, including publication year (regression coefficient -0.0135, p=0.578), sample size (regression coefficient -0.0007, p=0.074) and human development index (regression coefficient -1.6263, p=0.419). Also, subgroup analysis of the pooled G. duodenalis infection was performed for publication year, World Health Organization regions, countries, continents, cancer types and country income.