Neoadjuvant and adjuvant radio- and radio-chemotherapy of rectal carcinomas

The objectives in treating rectal cancer are to achieve locoregional tumor control and to prolong overall survival. With surgery alone the reported local failure rates in recent decades have been unacceptably high, and this is associated with substantial morbidity and mortality. Perioperative radiotherapy with or without concomitant chemotherapy has been used extensively to reduce the high frequency of local recurrence. Adjuvant radiotherapy reduces the local recurrence rate dramatically if the dose is high enough and is administered preoperatively. Although a higher dose has been used in most postoperative radiotherapy trials, the reduction has not proven particularly pronounced. If the reduction were as great as that with preoperative radiotherapy, it would also have a positive effect on survival, which as yet has not been achieved with postoperative radiotherapy. However, postoperative irradiation combined with chemotherapy yields a survival benefit of the same magnitude as preoperative irradiation. Modern radiation techniques allow preoperative radiotherapy to be delivered without interfering substantially in the postoperative healing process; it does not increase mortality or morbidity and entails a low rate of late toxicity if the radiation technique is optimal. A major question today is whether radiotherapy is necessary if surgery is optimal. Control trials report an average local recurrence rate of 29% with standard surgery. With optimal surgery the figure reported from institutional series is about 10%. Other questions to be answered include whether to use superfractionation or standard fractionation in radiotherapy, and how chemotherapy should be given, concomitantly to radiotherapy or in the classical method of postoperative intravenous treatment.