Radiotherapy was given postoperatively to 37 out of 81 patients with metastases into the regional lymph nodes (stage C after Dukes) to prevent relapse. All the patients had undergone radical surgery. No significant decrease in relapse incidence could be achieved unless an absorbed dose of 40 Gy was received postoperatively. However, combined treatment failed to produce a significant rise in five-year survival due to deaths from distant metastases.