Preoperative symbiotic supplementation alters gut microbiota in colorectal cancer patients

BACKGROUND: Patients undergoing major surgeries, such as intestinal resections for colorectal cancer (CRC), present an increased risk of developing gut dysbiosis, which may be related to postoperative complications. However, biotherapeutic agents, such as symbiotics, are able to maintain intestinal homeostasis. We therefore explored the impact of preoperative symbiotic supplementation on the intestinal microbiota (IM) of patients with colorectal cancer undergoing surgical treatment. METHODS: This was a single-center, parallel, triple-masked, randomized clinical trial carried out at Federal University of Minas Gerais Hospital, Belo Horizonte, Minas Gerais, Brazil (https://clinicaltrials.gov/study/NCT04874883) comprised of adult patients diagnosed with CRC for tumor resection surgery. Patients were randomized to receive two sachets (6 g each) of symbiotic (S group) or maltodextrin (C group) twice a day for 4-10 d prior to surgery. All patients underwent nutritional and anthropometric assessments, as well as food consumption, bowel function, and digestive complaint assessments during the pre- and postoperative periods. Stools were collected before treatment (T1), after surgery (T2), and before hospital discharge (T3) to assess IM diversity and short-chain fatty acids. Normal tissue and tumor tissue fragments were collected during surgery for evaluation. RESULTS: A total of 46 patients were enrolled in the study, with 23 subjects in each group. No differences were seen between the groups regarding clinical or infectious complications (P > 0.05). The IM of stools collected at T2 showed a significant increment for the phylum Firmicutes, family Bacillaceae, and genus Blautia in the S group compared with the C group (P < 0.05). Furthermore, in those patients with infectious complications, the relative abundance of the Proteobacteria phylum was significantly lower in the S group compared with the C group (P < 0.05). Higher butyrate production was found at T2 and T3 in the S group, while acetate and propionate production were increased at T2 (P < 0.05). Additionally, the S group showed increased mucus production in the tumor tissue (P > 0.05). CONCLUSION: Preoperative symbiotic supplementation in patients with CRC undergoing tumor resection positively altered IM diversity, and increased short-chain fatty acid and mucus production.