Pathology of the mid-lower rectal carcinoma ZHU Xiong-zeng. Department of Patholgy, Cancer Hospital, Fudan University, Shanghai 200032, China Abstract The rectum is the most common site of the large bowel carcinoma. In rectal carcinoma, about 70% cases are located in the mid-lower rectum. Also some issues have been mantioned at histopathological diagnosis, including (1) the concept of the intraepithelial neoplasia (I N) and the relationship with surgical treatment, especially introducing the Vinna classification of gastronitesinal epithelial neoplasia and clinical management. (2) the prognostic paremeters determined by histopathology, such as resected margins, extent of extracolorectal invasion, reginal nodal metastases, vascular and perineural invasion, and (3) genetics of the large bowel cancers, mainly about hereditary nonpolyposis colorectal cancer(HNPCC) and familial adenomatous polyposis(FAP).