Radiologic diagnosis of early colorectal cancer (CRC) concerning fine invasion depth of cancer was discussed in relation to endoscopic mucosal resection. For the radiologic diagnisis of early CRC including superficial cancer lateral luminal rigidity is the keenest finding which discriminate mucosal (and slightly invasive submucosal) cancer and deeply invasive submucosal cancer.

Natural history of early CRC was discussed with retrospective radiographic analysis. Growth speed of early CRC was accelerated when cancer invaded deeply in the submucosa. In comparison of growth speeds of cancers with different macroscopic features, the growth speeds of superficially depressed cancer were not higher than that of elevated cancer. Accordingly, it is possible to estimate that early CRC grows on a growth curve. From analysis of our data, estimated doubling time of the volume of early CRC was 26 months. From these results we could obtain a rational cancer surveillance program using appropriate procedures. However, histologic and genetic factors which effect tumor growth remain to be solved.