Effect of probiotic supplementation on chemotherapy and radiotherapy-related diarrhea in patients with cancer: An umbrella review of systematic reviews and meta-analyses.

To date, several systematic reviews and meta-analyses (SRMAs) have investigated the effects of probiotics, but the certainty of the evidence for an effect on chemotherapy and radiotherapy-related diarrhea has not been assessed. We conducted an overview of SRMAs, searching MEDLINE, Scopus, and ISI Web of Science from inception up to February 2022. We summarized the findings of eligible SRMAs. Subsequently, we included RCTs from the SRMAs in meta-analyses, using a quality effects model to calculate the Odds ratio (ORs) and 95% confidence intervals (95%CIs) for each outcome. We used 'A Measurement Tool to Assess Systematic Reviews' (AMSTAR 2) and the Cochrane risk of bias (RoB) tool to assess the methodological quality of the SRMAs and their RCTs, respectively. We used the 'Grading of Recommendations Assessment, Development, and Evaluation' (GRADE).We included 13 SRMAs, which reported pooled effect sizes for chemotherapy and radiotherapy-related diarrhea based on a total of 18 RCTs. Our meta-analyses demonstrated statistically significant beneficial effects from probiotics on all outcomes, except stool consistency; diarrhea (any grade) OR 0.35 (95%CI 0.22, 0.54), grade ≥2 diarrhea 0.43 (0.25, 0.74), grade ≥3 diarrhea 0.30 (0.15, 0.59), use of medication 0.49 (0.27, 0.88), soft stool 1.10 (0.44, 2.76) and watery stool 0.52 (0.29, 1.29). Probiotics use can reduce the incidence of diarrhea in cancer patients in chemotherapy and radiotherapy, but the certainty of evidence for significant outcomes were very low and low.