Post-operative radiotherapy is associated with improved survival in esophageal cancer with positive surgical margins

Background: The optimal treatment for early-stage esophageal cancer with positive surgical margins after an upfront esophagectomy is not well-defined. This study investigates the effect of post-operative radiotherapy (PORT) on overall survival (OS) in clinical stage I-II patients with positive margins.

Methods: We identified patients diagnosed between 2004 and 2012 with clinical stage I-II esophageal carcinoma from the National Cancer Data Base (NCDB) who underwent an upfront esophagectomy. For those patients with positive margins, administration of PORT was recorded, and OS was compared by the Kaplan-Meier estimator and log-rank test. Multivariable Cox regression analysis was performed to identify variables associated with improved survival.

Results: Among the 3,490 patients identified, 209 (5.8%) had positive margins. One hundred forty-two (67.9%) patients did not receive PORT while 67 (32.1%) did receive PORT. Compared to those receiving PORT, patients who did not receive PORT were significantly older (68.5 vs. 64.0 years, P=0.003), more likely to have pN0 disease (50.7% vs. 35.4%, P=0.026), and less likely to receive postoperative chemotherapy (21.1% vs. 86.6%, P<0.001). On multivariable logistic regression, only receipt of chemotherapy predicted for receipt of PORT (OR: 25.6, 95% CI: 9.9-65.8, P<0.001). OS was significantly higher for patients receiving PORT compared to those who did not (median OS: 32.2 vs. 16.9 months, log-rank P=0.008). Multivariable analysis confirmed an association with PORT and improved OS (HR: 0.39, 95% CI: 0.27-0.60, P<0.001). Subset analysis demonstrated that the OS benefit of PORT persisted in those patients who received adjuvant chemotherapy (HR: 0.33, 95% CI: 0.19-0.57, P<0.001).

Conclusions: PORT is associated with improved OS in clinical stage I-II esophageal cancer patients after an upfront esophagectomy with positive margins. In the absence of prospective randomized data, our findings suggest that PORT should be strongly considered in the setting of early-stage esophageal cancer resected with positive margins.