[en] Radiation therapy has been used in patients with colorectal cancer with increasing frequency over the past two decades. Preoperative and postoperative radiation therapy, alone or in combination, have been shown to significantly reduce local failure rate, and combinations including intraoperative radiotherapy have also proved effective. While there is no doubt that surgical resection remains the primary treatment for colorectal cancer, combinations of surgery and radiation in an adjuvant setting such as intraoperative radiotherapy should be considered when designing multimodal treatment programs. Such combinations may further increase local control and long-term cure rate, and decrease rate of postoperative urinary and sexual dysfunction. Both surgical and radiation oncologists must work closely together to achieve a suitable therapeutic ratio, to increase control with minimum risk. (author)