The current study aims to evaluate the potential roles of taking probiotics postoperatively in attenuating the gastrointestinal complications and disturbed gut microbiota in colorectal cancer (CRC) patients undergoing chemotherapy. One hundred eligible CRC patients who were treated with radical surgery and needed to receive chemotherapy were recruited. Half of them were randomly assigned to the Probio group to take a probiotic combination from post-operation to the end of the first chemotherapeutic course. The other half of patients taking placebo instead were classified as the Placebo group. Gastrointestinal complications such as nausea, acid reflux, abdominal pain, abdominal distention, constipation, and diarrhea were recorded during chemotherapy. Fecal samples were collected preoperatively and after the first cycle of postoperative chemotherapy for 16S rRNA high-throughput sequencing and short-chain fatty acids (SCFAs) analysis. Results showed that probiotics administration could effectively reduce chemotherapy-induced gastrointestinal complications, particularly in diarrhea (p < 0.01). Additionally, chemotherapy also reduced the bacterial diversity indexes of the gut microbiota in CRC patients, which could be significantly increased by taking probiotics. Moreover, this chemotherapy caused significant changes in the composition of the gut microbiota, as indicated by decreased phylum levels of Firmicutes and increased Bacteroidetes, Proteobacteria, and Verrucomicrobia. In particular, several bacterial genera such as Akkermansia and Clostridium were significantly increased, while Prevotella, Lactobacillus, and Roseburia were decreased (p < 0.05). However, probiotic administration could effectively restore these taxa changes both at the phylum and genus levels, and mildly increase the genus levels of Bifidobacterium, Streptococcus, and Blautia. Furthermore, probiotics could also promote the production of SCFAs, particularly increasing acetate, butyrate, and propionate (p < 0.0001). These results support the beneficial effects of the probiotic interventions as novel alternative or complementary strategies in chemoprevention.
Keywords: CRC; chemotherapy; gastrointestinal complications; gut microbiota; probiotics.