Tales from the human crypt--intestinal stem cell repertoire and the origins of human cancer.

A generally accepted model for the origin of human cancer is that tumours arising from the gut-lining epithelium--the adenomas and carcinomas--are of clonal origin, i.e., they are derived from a single 'abnormal' cell. Recent work has shed considerable light on these matters and suggests that this model may be erroneous and that at least some adenomas are of multiclonal origin. These findings have basic implications for more generalized models of tumourigenesis and for researchers examining the potential clinical value of gene therapy.