New aspects of adjuvant radiotherapy in primarily resectable rectal cancer

Abstract

Local recurrence rates of approximately 30% have been consistently reported after 'conventional surgery' in stage II + III rectal cancer patients. Postoperative radiotherapy decreases the local recurrence rate only moderately and is not associated with a gain in survival. Preoperative radiotherapy with biologically effective doses > 30 Gy dramatically reduces the relative risk of local recurrences by 57% that translates into significant overall survival benefit. Postoperative 5-fluorouracil-based chemotherapy in combination with radiotherapy has also been shown to increase local tumor control and to result in a significantly better survival. However, an improved surgical technique, the total mesorectal excision (TME), has evolved and is considered standard treatment by many surgeons. With this technique, reduced local recurrence rates of below 10% and improved survival rates have been reported from different institutions. Therefore, a discussion has started, whether or not pre- or postoperative radiotherapy and chemotherapy is beneficial, when TME is used. The preliminary results of a recently published trial on radiotherapy before TME partly resolve the current controversy. An expected local failure rate of approximately 15% and an overall survival rate below 60%, 5 years after TME alone in stage II + III rectal cancer patients suggest the need for additional therapy. Preoperative radiotherapy reduced the risk of local recurrence more than 3 times, indicating that the use of radiotherapy is justified at least in patients with stage II + III disease, even if optimal surgery was used. The unsatisfactory overall survival gives indirect evidence that these patients will also benefit from chemotherapy. However, many questions remain open and an optimal therapeutic schedule has not been established.