Symposium on carcinoma of colon and rectum: 3. Radiation therapy in rectal cancer.

In a number of studies preoperative irradiation of cancer of the rectum has procured 5-year survival rates higher than those obtained with conventional surgical techniques, whether or not the tumour has spread to lymph nodes. There appears, as well, to be a lower rate of local recurrence and possibly of the development of distant metastases. Also, some tumours of questionable operability are reduced in size to make resection possible. The effectiveness of postoperative radiation therapy is not yet firmly established. Radiation therapy as the primary method of treatment of rectal carcinoma has been used at the Princess Margaret Hospital in Toronto in 79 patients over a period of 18 years. The overall 5-year survival rate is 28%; this rises to 38% when the tumour is not fixed but falls to half this figure when fixity of the growth is evident. These results offer grounds for investigating radical radiation therapy as an alternative to surgical methods of dealing with low-lying carcinomas of the rectum.