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

Abstract

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 T 1–T 2 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 T 2 or T 3 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 T 2 or T 3 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.