Tumor characteristics in colorectal cancer and their relationship to treatment and prognosis.

Two hundred sixty one patients with adenocarcinoma of the colon and rectum were studied with respect to histopathologic and macroscopic tumor characteristics. Nonmetastatic disease was associated significantly with well-differentiated tumors, tumors with pronounced inflammation, and polypoid adenocarcinomas. There was a higher proportion of poorly-differentiated tumors in the right colon. Inflammatory changes were uncommon in rectal lesions; these tumors were more often polypoid than in other locations. Survival was significantly influenced by tumor differentiation, degree of inflammation, macroscopic appearance, and tumor size. Well-differentiated adenocarcinomas, less than 2 cm in diameter, and well-differentiated polypoid adenocarcinomas, less than 4 cm in diameter, were all found in patients with Dukes' stage A tumors. Such patients may be candidates for local excision if the tumor is located in the distal part of the rectum.