Smoking induces the occurrence of colorectal cancer via changing the intestinal permeability.

Purpose Colorectal cancer (CRC) is the third most frequent cancer. Its occurrence is closely linked to lifestyle and diet habits, such as excessive intake of high-fat food, but their impact on CRC, however, remain unclear. Methods Eligible CRC patients were retrospectively analyzed. Overall survival (OS) and recurrence-free survival (RFS) in smokers and non-smokers of CRC patients were assessed. APCmin/+ mice were exposed to cigarette smoking, followed by detection of CRC growth and intestinal permeability. Results A total of 416 eligible CRC patients were recruited, involving 218 (52.4%) smokers and 198 (47.6%) non-smokers. OS was shorter in CRC smokers than in non-smokers (p=0.005), whereas smoking did not affect RFS in CRC patients (p=0.251). Cigarette smoking increased CRC tumor numbers of CRC in APCmin/+ mice. Proliferation and apoptosis of colorectal epithelial cells, and inflammatory response in mice were changed following smoking. Notably, the treatment of probiotics mixture VSL#3 decreased the number of CRC tissues and intestinal permeability in APCmin/+ mice exposed to cigarette smoking. Conclusions Smoking increases the susceptibility to CRC through damaging the intestinal permeability. Protecting the intestinal permeability significantly protects intestinal tracts.