Abstract: Decreasing trend has occurred in incidence of colorectal cancer in developed countries. A shift from left to right in location of colorectal cancer has been recognized, which may be associated with colonoscopy screening, aging population, diet structure modification, increased incidence of cancer and diabetes. Factors including sex, race and education may also play a role to some extent. Rightsided intestinal cancers have higher proportion of poor differentiation, terminal stage and mucinous component. Complications and second primary intestinal cancer are more common in rightsided intestinal cancers. Leftsided intestinal cancers tend to be well differentiated and at relatively early stage at diagnosis. With respect to molecular mechanism, rightsided cancers are associated with mismatch repair system, while leftsided cancers are related to p53 mutation. Based on the differences in clinicopathology and genetics, it′s implied that leftsided and rightsided intestinal cancers may belong to two different kind of disease. It′s suggested that attentions should be paid differently according to their respective characteristics in clinical practice and trials.

Key words: Colorectal neoplasms, Disease attributes, Neoplasm site