Definition

Stage III colorectal cancer is divided into stages IIIA, IIIB, and IIIC. In stage IIIC, cancer has spread (1) through the serosa (outermost layer) of the colon and/or rectum wall to the tissue that lines the organs in the abdomen (visceral peritoneum). Cancer has spread to 4 to 6 nearby lymph nodes; or (2) through the muscle layer of the colon and/or rectum wall to the serosa of the colon and/or rectum wall or has spread through the serosa to the visceral peritoneum. Cancer has spread to seven or more nearby lymph nodes; or (3) through the serosa of the colon and/or rectum wall to nearby organs. Cancer has spread to one or more nearby lymph nodes or cancer cells have formed in tissue near the lymph nodes.