Endocavitary irradiation in the conservative treatment of adenocarcinoma of the low rectum.

Early T1 and small T2 low rectal cancers may be controlled by endocavitary irradiation using the 50 kV Philips machine. The ambulatory treatment performed in the out-patient department consists of 4 applications within 6 weeks. Iridium-192 implant performed under local anesthesia is useful in many cases to give a booster dose to the tumor bed. In a series of 312 patients followed for greater than 5 years, the rates of local and nodal failure were 4.5% and 3.8%, respectively. The rate of death from cancer was 7.7%. After local excision endocavitary irradiation may be used as adjuvant therapy but it is safer to combine external beam and endocavitary irradiation. In the particular case of very poor risk patients with T2 or T3 tumors of the lower third of the rectum, a short course of external beam irradiation (30 Gy within 12 days) followed 2 months later by endocavitary irradiation may be a reliable procedure to prevent permanent colostomy in cases selected according to the patient's condition and the features of the residual disease. Of 67 patients followed for greater than 5 years, 3 patients died of distant metastasis and 5 patients died of local failures. These data, based on close collaboration with surgeons, suggest a reappraisal of the role of radiation therapy in the conservative management of rectal cancer.