Radiation therapy as definitive treatment for selected invasive rectal cancer

Eighty-four patients with invasive rectal adenocarcinoma were definitively treated with radiation during a period of 9 years in an attempt to achieve "local control" (eradication of rectal cancer and its associated morbidity) without radical resective surgery.

Initially, endocavitary radiation alone was used in 13 patients with "ideal" carcinomas and in six patients with aggressive cancers. To improve local control, 4500 cGy external radiation before the 6000 cGy endocavitary radiation was used to treat 28 ideal lesions, 15 "nonideal" but potentially curable cancers, 14 aggressive cancers, and 8 patients with incurable metastatic disease.

Endocavitary radiation alone resulted in local control for 8 of 13 patients with ideal carcinomas (62%); eventually 11 of 13 (85%) had control after three successful salvage abdominoperineal resections. Local control was accomplished in none of six patients with aggressive cancers. Use of external radiation before endocavitary radiation achieved local control in 93% of patients with ideal lesions, eventually 100% after two salvage abdominoperineal resections. Of the 15 nonideal but potentially curable lesions, 100% had eradication of local disease with the combined modalities. Of the 14 with aggressive cancers and 8 with metastatic disease, 19 suffered failure of local control (86%). Eight of these had local salvage by surgical resection; the others died with local failure within 6 months.

External radiation, combined with endocavitary radiation, is excellent, definitive treatment for selected, favorable, invasive rectal cancers; however, there is little place for nonresective management of aggressive rectal cancer, even for palliation, unless life expectancy is less than 6 months.