Cancer is rarely detected in the right-sided colon because genes' function of ejecting tumor cells and other foreign substances there is as strong as in the small intestine, which has a powerful immune system, a Japanese research team announced Friday.

It has been known that colorectal cancer occurs in the left-sided colorectum at an incident rate of some 80% while the small intestine and the right colon are almost cancer-free.

Through endoscopic intestinal step biopsies and exhaustive genetic analysis, the group of researchers from the National Cancer Center and Osaka University found that the expression of genes related to xenobiotic stimulus and antimicrobial peptide is high in the right colon.