Present status of radiation therapy in the conservative management of rectal cancer.

Conservative treatment of rectal cancer may be a valid alternative to radical surgery in cases selected with regard to their very low probability of lymphatic spread. Beside the surgical modalities of local treatment, radiation therapy has gained a substantial place thanks to the use of intracavitary irradiation (contact X-ray therapy and interstitial curietherapy). In a series of 310 cases of T1-T2 tumors followed more than 5 years, the rate of death of cancer is 7.7% and the rate of local failures is 5%, significantly inferior to that following local excision or electrocoagulation. Moreover, in elderly poor risk patients with T2 or T3 tumors of the lower third of the rectum, it is possible to extend somewhat the field of conservative treatment without jeopardizing their chance of cure. The protocol is based on a short but intensive course of external beam irradiation (30 Gy over 12 days) followed 2 months later by intracavitary irradiation directed to the tumor bed. The purpose of this strategy is a tentative conversion of low-lying tumors suitable for abdominoperineal resection into lesions amenable to conservation. In a series of 71 patients (mean age 74 years) with selected T2 or T3 tumors larger than 4 cm, followed more than 3 years, the rate of death of cancer is 11% and the rate of death of intercurrent disease is 22%. At 5 years the rate of death of cancer is 16%. It is emphasized the necessity of a strict selection of cases by clinical means and endorectal sonography. This strategy must only be conceived as a teamwork of radiation therapists and surgeons.