Symposium on the diagnosis and treatment of common cancers. 3. Colorectal carcinoma.

Current efforts to reduce the morbidity and mortality of colorectal adenocarcinoma are directed mainly to earlier diagnosis and the development of effective surgical adjuvant treatment. The most generally available screening technique is the identification of fecal occult blood, but numerous false-negative and false-positive findings, and the large population at risk, suggest that more effective but time-consuming screening methods, such as endoscopy, should be reserved for high-risk groups. More extensive pelvic and para-aortic lymph-node dissections for rectal adenocarcinoma have not resulted in consistently improved survival rates. Radiotherapy reduces the frequency of pelvic recurrence when given as either preoperative or postoperative adjuvant therapy for rectal cancer but has not yet produced any major improvement in survival. No effective adjuvant chemotherapy for colorectal adenocarcinoma has yet been identified. Primary radiotherapy can control a proportion of rectal carcinomas and may reduce the need for colostomy in some cases.