Modulating the Gut Microbiome in Colorectal Cancer: A Scoping Review Protocol of Chemotherapy Combined with Synbiotics and Their Effects on Treatment Response and Microbial Diversity

Adjunctive synbiotic therapy in metastatic colorectal cancer patients undergoing chemotherapy is posited to restore gut microbial diversity, enhance beneficial short-chain fatty acid-producing taxa such as Bifidobacterium and Lactobacillus, and diminish dysbiosis-associated pathobionts, thereby elevating butyrate and other SCFAs that fortify epithelial barrier integrity and exert anti-inflammatory and anti-cancer effects. Synbiotics are intended to increase the levels of anti-inflammatory cytokines like IL-10 while decreasing IL-6 and TNF-α. This will make the mucosal defenses stronger, lessen the damage and dysbiosis caused by chemotherapy, and make it easier to tolerate treatment. These anti-inflammatory, barrier-protective, and immunomodulatory effects are thought to boost the body's ability to fight tumors and lead to better tumor response rates and fewer side effects from chemotherapy than chemotherapy alone.