Is extended volume external beam radiation therapy covering the anastomotic site beneficial in post-esophagectomy high risk patients?

Background and purpose: To assess the impact of extended volume radiation therapy (RT) with anastomotic coverage on local control in high risk post-operative esophageal cancer patients. Patients and methods: This is a retrospective study of high risk (T3, T4, nodes positive, with or without margin involvement) post-operative esophageal cancer patients treated at London Regional Cancer Centre from 1989 to 1999. After esophagectomy, all patients received adjuvant combined modality therapy consisting of four cycles of fluorouracil-based chemotherapy, and loco-regional RT with or without coverage of the anastomotic site. RT dose ranged from 45 to 60 Gy at 1.8-2.0 Gy/fraction with treatment fields tailored to the pathologic findings and location of the anastomosis. CT planning was used in all patients to design spinal cord sparing beam arrangements. First relapse rate (first incidence of an event), disease specific survival and overall survival were calculated by Chi-Square, Log-Rank, and Kaplan-Meier (K-M) methods. Results: During the study period, 72 patients had underwent esophagectomy and were considered for adjuvant chemoradiation therapy. Three patients were excluded due to disease progression prior to therapy. The 69 remaining patients formed the study cohort for the present analysis. The median age of the study group was 60 years (range 35-82 years). Pathologic stage distribution (AJCC 1997 staging) was T2,3 N1 in 94% patients, 65% of the cases were adenocarcinoma and had undergone transhiatal esophagectomy (86%) with positive/close margins in 34 (49%) patients. Median follow-up was 30.5 months (range 3.4-116.3 months). Two- and 5-year actuarial overall survivals rates were 50 and 31%, respectively. First relapse rate after adjuvant therapy was 63.7% (n=44) and median time to relapse was 27.2 months. Anastomosis recurrence rates were 29% with small volume and 0% with extended volume RT (P=0.041). Local and regional relapse occurred in 74.2% of patients treated with small volume RT compared to 15.4% in patients treated with extended volume RT (P<0.001). After adjusting for resection margin status, the local control benefit of extended volume RT remained significant (P=0.003). Treatment interruptions and late gastrointestinal toxicity were not significantly increased with the use of extended volume RT. Conclusions: A significant decrease in local and regional relapse without added late toxicity was achieved with the use of extended volume RT encompassing the anastomotic site post-operatively in high risk esophageal cancer patients