Radiotherapy of colorectal cancer.

Radiotherapy has an increasingly important place in the management of patients with colorectal cancer. At present the exact indications have not been made based on preliminary experience at the Princess Margaret Hospital, Toronto: 1. Radical irradiation could be a valuable alternative to the classical Miles' abdominoperineal excision of extraperitoneal rectal cancer. 2. Preoperative irradiation may be used for all patients undergoing surgical excision and restoration of bowel continuity. 3. Postoperative radiotherapy can be administrated (a) when the tumour has penetrated the bowel wall to the serosa or beyond, (b) when the lymph nodes are involved secondarily and (c) when the distal line of resection is less than 4.0 cm from the tumour (as measured in the fixed pathological specimen). 4. Radiotherapy is useful for palliation of postsurgical recurrences and symptomatic distant metastases.