Perioperative radiotherapy in rectal cancer.

Local failure of rectal cancer is one of the principal causes of morbidity and mortality. In order to lower unacceptably high local failure rates, pre- or postoperative radiotherapy has been extensively investigated. The collected information from all controlled trials reported so far shows that the proportion of local recurrences is reduced to less than half when radiotherapy up to moderately high doses is given preoperatively. This reduction is smaller after postoperative radiotherapy, even if higher doses are used. In addition, there is a positive influence on survival from preoperative radiotherapy. Improved survival has also been seen in trials using postoperative radiotherapy, but only when combined with chemotherapy. With proper radiation techniques, sufficiently high doses can be given preoperatively with little, if any, increase in postoperative mortality and morbidity. Furthermore, late toxicity can be anticipated to be low provided the technique is optimal. The beneficial effects noted so far have been achieved in trials where 'standard' surgery has been used, followed by a local recurrence rate of more than 20% (average 29%, range 23-46%) of the patients. It is, however, possible that the reduction in local failure rates is proportionally even greater added to 'optimal' surgery, although the absolute number of failures prevented is lower.