Obesity is thought to increase the chance of developing many cancers, including colorectal cancer (CRC). In addition to lowering overall cancer risk, bariatric surgery has been linked to improvements in co-morbidities brought on by obesity. However, the effect of bariatric surgery on CRC risk is debatable given the contradictory results of various cohort studies. Additionally, after Roux-en-Y gastric bypass (RYGB), evaluation of CRC biomarkers has shown hyperproliferation and elevated pro-inflammatory gene expression in the rectal mucosa. Alterations in the gut microbiota and exposure to high bile acid concentrations in the colorectum, both of which are brought on by RYGB-induced anatomical rearrangements, are the two hypothesised pathways for increased CRC risk. The parallels between the RYGB-induced microbial profiles and the gut microbiota seen in CRC have been noted in studies in both animals and humans.
