Abstract
It is considered that primary colonic cancers located proximal (right) or distal (left) to the splenic flexure of the colon may belong to the different categories of the disease in terms of the clinicopathological and physiological features. Recent extensive advance in the molecular biology supports an idea that accumulated genetic changes underlie the development of colorectal cancer. It has been proven that two distinct genetic pathways are reponsible for colorectal carcinogenesis and each of the tumor is preferably located in the different side of the colon. In this study, hereditary and environmental factors of cancers arisen from the right and left side of the colon were analyzed. It is inferred that differences in the embryologic origin of colonic epithelium of proximal and distal segments may determine differences in the susceptibility to environmental carcinogenes and select the genetic pathway of carcinogenesis.
The notion is supported by epidemiologic and molecular studies of colorectal cancer. In the future, therapeutic strategies for colorectal cancers may be selected depending on hereditary and environmental factors of the tumor which are different between tumors in the right and left side of the colon, as well as molecular characteristics of each tumor.
