ENDOSCOPIC DIAGNOSIS AND TREATMENT OF EARLY COLORECTAL-CANCER

Colorectal adenomas and early cancers are grossly classified into thre e groups: protruded, Bush or slightly elevated (so-called Bat adenomas ), and depressed. Protruded lesions and flat adenomas are not invasive until they are rather targe, whereas depressed lesions can invade the submucosa even when very small. It is not difficult to detect protrud ed and flat adenomas, but depressed carcinomas are often overlooked. K eys to the detection of depressed carcinomas are a slight color change , bleeding spots, interruptions of the capillary network pattern, slig ht deformation of the colonic wall, shape change of the lesion with in sufflation and deflation of air? and interruption of the innominate gr ooves by the lesion. Spraying of indigo carmine dye helps to clarify t he lesions. Pit pattern analysis with magnifying colonoscopy is useful fur diagnosis of early colorectal cancer. Pit pattern analysis and hi stologic examination suggest that depressed carcinomas probably have a risen de novo, without going through an adenomatous step. Some adenoma s appear at first to have a depression, but such cancer-mimicking aden omas with pseudodepression must be distinguished from depressed carcin omas because they are quite different in nature. Protruded and flat ad enomas can usually be removed with polypectomy dr hot biopsy technique s. Depressed carcinomas are treated with an endoscopic mucosal resecti on (EMR) technique; but when they massively invade the submucosa, surg ical resection is indicated. Some neoplastic Lesions, which we call la terally spreading tumors, extensively and circumferentially spread alo ng the colonic wall, although they are short in height. They tend to h ave a rather benign nature despite their large size; therefore EMR or a piecemeal EMR method is indicated.