Adjuvant therapy for resectable rectal and colonic cancer.

BACKGROUND: Recurrence of rectal and colonic carcinoma remains substantial despite apparently curative surgery. Adjuvant therapy has been applied to improve prognosis.
METHODS: This review evaluates the use of adjuvant therapy in the management of resectable rectal and colonic carcinoma. It assesses critically the evidence supporting the addition of radiotherapy, chemotherapy, chemoradiotherapy and other treatment modalities to optimal surgery.
RESULTS: In the case of rectal tumours, preoperative is more effective than postoperative radiotherapy; It can significantly reduce the incidence of local tumour recurrence. A number of trials have tended towards showing a survival advantage and a recent large randomized trial has shown a significant improvement in survival in patients with Dukes C tumours. Postoperative chemoradiotherapy is associated with a survival benefit and is standard therapy in the USA, although it is associated with increased toxicity. The effectiveness of preoperative chemoradiotherapy is currently being investigated. Postoperative fluorouracil-containing chemotherapy has resulted in a survival advantage in patients with Dukes C colonic tumours; such therapy may be administered either systemically or intraportally. The evidence of benefit with rectal tumours is more limited. Immunotherapy has been studied to a limited extent and the use of a tumour-directed monoclonal antibody has produced a survival advantage in a single trial.
CONCLUSION: Preoperative radiotherapy and postoperative chemoradiotherapy can produce a survival advantage in patients with Dukes C rectal carcinoma and reduce local recurrence. Postoperative fluorouracil-containing chemotherapy can produce a survival advantage in those with Dukes C colonic cancer. The optimal use and combination of adjuvant therapy remains uncertain.