AbstractContextClinical trials have investigated the effect of probiotics on postsurgical complications in colorectal cancer (CRC). However, so far, there are no systematic reviews evaluating the effect of probiotics and synbiotics on the clinical or infectious postsurgical complications of colorectal cancer.ObjectiveThe objective of this review was to synthesize the best available evidence on the effects of the use of probiotics or synbiotics on pre-, peri-, and post-operative complications of CRC surgical resection.Data SourcesA search of the PubMed, Embase, LILACS, Scopus, Cochrane, Web of Science, ProQuest, and Google Scholar databases was conducted for clinical trials published up until January 2022.Data ExtractionThe population characteristics, period and protocol of supplementation, and postoperative complications were extracted and reported. A random-effects model was used to estimate the effect of probiotic and synbiotic treatment on these variables.Data SynthesisIn total, 2518 studies were identified, of which 16 were included in the qualitative synthesis and 13 in the meta-analysis. Overall, probiotic supplementation reduced the incidence of ileus (odds ratio [OR] = .13, 95% confidence interval [CI]: .02, .78), diarrhea (OR = .32, 95% CI: .15, .69), abdominal collection (OR: .35, 95% CI: .13, .92), sepsis (OR = .41, 95% CI: .22, .80), pneumonia (OR = .39, 95% CI: .19, .83), and surgical site infection (OR = .53, 95% CI: .36, .78). The results of the subgroup analysis indicated that lower dose (<109 colony-forming units), higher duration of supplementation (>14 days), and being administrated ≤5 days before and >10 days after surgery was more effective at reducing the incidence of surgical site infection.ConclusionProbiotics and synbiotics seem to be a promising strategy for the prevention of postoperative complications after CRC surgery. Larger, high-quality randomized controlled trials are needed to establish the optimal treatment protocol for the use of probiotics and synbiotics in preventing postoperative complications for CRC surgery.