Pathology of early lower GI cancer

Early colorectal cancer can be treated with curative resection if the depth of invasion is limited to the submucosa (pathologic T category pT1 in the TNM classification). Macroscopically early colorectal cancer and its precursor lesions present as elevated polyps or non-polypoid flat lesions. Microscopically, precursor lesions are characterized by intraepithelial neoplasia and present as classic adenomas or serrated adenomas. Precursor lesions may already contain foci of early colorectal cancer. Early colorectal cancer can be treated by endoscopic resection. Careful handling of the specimen is required in order to optimally identify the factors that may predict an adverse outcome. Whenever a favourable tumour grade is found, without vascular invasion and tumour budding, there seems to be a low risk for adverse outcome and laparotomy may thus be avoided.