Adjuvant postoperative radiation therapy for Dukes C adenocarcinoma of the rectum.

This study was designed to explore the effects of adjuvant postoperative radiation therapy on the course and survival of patients with Dukes C adenocarcinoma of the rectum. Moderate dose radiotherapy was offered to 64 patients. Twenty-four accepted and were treated, while the remainder refused. With a mean follow-up of 32.3 months, the overall survival rate was 63% (40/64) and the mean disease-free survival rate at the time of this report was 45%. The following variables were analyzed separately: operative procedure, distance of the tumor from the anal verge, tumor size, and transmural, vascular, lymphatic and perineural invasion of tumor. The most significant differences between irradiated and non-irradiated patients were found in the group of patients whose lesions were 6 cm or less from the anal verge. Of the 19 such patients with an average follow-up of 36.4 months, ten patients were irradiated and nine were not irradiated. The irradiated group had a 90% (9/10) survival rate and 70% (7/10) of them were disease free; the non-irradiated group had a 44% (4/9) survival rate and 22% (2/9) of them disease free. It is concluded that patients with adenocarcinoma of the rectum metastatic to lymph nodes, whose lesions' lower border is measured 6 cm or less from the anal verge, benefit significantly from adjuvant postoperative radiotherapy.