The epidemiologic pathology of carcinomas of the large bowel

From the End Results Group file over 60,000 cases of histologically confirmed bowel cancers were analyzed by histologic type. Adenocarcinomas were the standard against which cancers with other diagnoses were compared. Colloid carcinomas occurred relatively frequently in blacks and in young persons, especially young men. In the left colon they had a worse prognosis than other cancers. Papillary carcinomas had a better than average prognosis while polypoid carcinomas had the best prognosis of any type of carcinoma. Adenosquamous and squamous cell carcinomas in the rectum closely resembled anal cancers; elsewhere in the bowel they behaved like aggressive adenocarcinomas. Malignant carcinoids of the appendix resembled benign carcinoids of that organ; elsewhere they were quite aggressive. Rectal carcinoids were unusually common in blacks. Grade appeared to be an independent prognostic parameter, although low grade of malignancy also implied an early stage. The differences in behavior by histology point up the importance of specificity of histologic diagnosis of cancers of the bowel. Comparisons of these observations with some other series are drawn, and the advantages and difficulties of this kind of analysis are discussed.