The Anti-neoplastic Effects of Probiotics and Prebiotics against Colorectal Cancer: A Systematic Review

With the world’s incidence of non-communicable diseases (NCDs) increasing, colon and rectal cancers now form the 3rd most common form of cancer globally, the need to find new solutions to colorectal cancer (CRC) is paramount, as current treatment is limited and comes with many unfavourable side effects. Studies on probiotic bacteria and prebiotic compounds spanning the last ten years reveal promising results describing their ability to act against colorectal cancer development. After screening papers with a specific inclusion criterion, 23 papers were selected for this review. The primary endpoints, biomarkers, and other data were analysed. The results show that overall, the prebiotics and probiotic bacteria included in this study (predominantly the genera Lactobacillus and Bifidobacterium) have promising anti-neoplastic effects against colorectal cancer, although in varying amounts. Other prebiotics such as fructooligosaccharides, branched fructans, and other plant extracts, were shown to have equally positive effects. The concept of using probiotics/prebiotics in addition to established cancer treatment seems more feasible with the various benefits highlighted in this review. At the very least, probiotics/prebiotics may be useful adjuvants, to be used alongside pre-existing colorectal cancer treatment. Probiotics/prebiotics may help alleviate some undesirable side effects of pre-existing treatment (i.e., fluorouracil) such as dysbiosis. Thus, this review aims to build upon the foundations established in microbiome research and encourage the course of future prebiotic and probiotic testing, to further our understanding related to the effect of probiotics/prebiotics on gut health and help treat the growing burden of colorectal cancer.