Epidemiology and carcinogenesis of rectal cancer

Cancer of the colon and rectum is extremely common in the Western hemisphere. The etiopathogenesis of colorectal cancer is an intertwined play of several genetic and environmental factors to which an individual is exposed to during the lifetime. The predominance of one factor over another decides the timing of development of this cancer with respect to the individual’s age. Familial syndromes like Lynch syndrome and familial adenomatous polyposis predispose an individual to cancer early in their lifespan since they carry the genetic mutation. A sporadic cancer, on the other hand, follows a very interesting and often predictable path from a polyp to carcinoma. There are three such pathways which the colonic epithelium may undertake toward the development of cancer. Each of the pathways has its own unique set of genotypic and phenotypic expression which needs to be understood well to accomplish our ultimate goal for prevention of colorectal cancer.