Prognostic Significance of Nodal Disease following Preoperative Radiation for Rectal Adenocarcinoma

Abstract

The administration of preoperative radiation (Pre-Op) therapy for adenocarcinoma of the rectum is evolving. The prognostic value of nodal disease found after preoperative therapy is unclear. The purpose of this study is to evaluate the impact of Pre-Op therapy on nodal staging and thus prognosis in patients with operable cancer of the rectum. Retrospective review of 292 cases revealed that 20% (N = 58) received Pre-Op radiation and 33% (N = 97) received Post-Op radiation. Of the Pre-Op group 66% received 5-fluorouracil-based chemotherapy concomitantly ( vs 48% Post-Op). Radiation dose averaged 50 Gy for both groups. Node-positive disease was found after Pre-Op therapy at a similar rate to that of Post-Op or surgery-only patients (45% vs 46%, P = 0.95). Fewer nodes were found in Pre-Op resection specimens (6.8 vs 10.0 nodes/specimen, P = 0.003), which altered the fraction of positive nodes (27% Pre-Op vs 18% Post-Op, P = 0.003). The N0 cases had better survival than N+ in both Pre-Op (80% vs 34%, P = 0.0001) and Post-Op (70% vs 40%, P = 0.02) groups. There was no significant difference in survival between Pre-Op versus Post-Op. Pre-Op chemoradiation improved patient survival over radiation alone and should be considered routinely with radiation therapy for rectal cancer. Pre-Op radiotherapy decreases the number of nodes recovered but does not influence the presence of nodal metastasis. Nodal disease remains a strong prognostic indicator of survival after Pre-Op radiation therapy.