Background: The gut microbiome, in particular Fusobacterium nucleatum, has been reported to play a role in colorectal cancer development and in patient prognosis. We aimed to perform a systematic review and meta-analysis of published studies to assess the prevalence of F. nucleatum in colorectal tumors and evaluate the association between F. nucleatum and colorectal cancer development and prognosis.Methods: MEDLINE, EMBASE, and Web of Science databases were systematically searched for studies published until January 2019. Random effects meta-analyses were used to assess the prevalence of F. nucleatum in patients with colorectal cancer or tissues relative to controls and survival in F. nucleatum-positive versus -negative patients.Results: Forty-five relevant articles were identified. Meta-analyses indicated higher odds of F. nucleatum being present in colorectal tissue samples from patients with colorectal cancer [n ¼ 6 studies, pooled OR ¼ 10.06; 95% confidence intervals (CI), 4.48-22.58] and individuals with colorectal polyps (n ¼ 5 studies, pooled OR ¼ 1.83; 95% CI, 1.07-3.16) compared with healthy controls. Similar results were apparent in fecal samples, and when comparing tumor with adjacent normal tissue. Meta-analyses indicated poorer survival in patients with colorectal cancer with high versus low F. nucleatum abundance (n ¼ 5 studies, pooled HR ¼ 1.87; 95% CI, 1.12-3.11).Conclusions: A consistent increase in the prevalence and/or abundance of F. nucleatum in colorectal cancer tissue and fecal samples compared with controls was apparent. High abundance of F. nucleatum in colorectal tumors was also associated with poorer overall survival.Impact: F. nucleatum could be useful as a diagnostic and prognostic marker for colorectal cancer or as a treatment target. Materials and Methods Data sourcesAn a priori systematic search of the literature was performed in accordance with PRISMA guidelines (Supplementary Table S1; ref. 14