Downstaging and survival after neoadjuvant approaches to gastroesophageal junction adenocarcinoma.

Abstract

92 Background: Outcomes after neoadjuvant chemoradiation (NACRT) versus chemotherapy alone (NAC) in gastroesophageal junction (GEJ) adenocarcinoma are unclear, as such tumors can be treated with equipoise using either approach. Methods: We included patients in the National Cancer Database with non-metastatic T2-4 or N1-3 GEJ adenocarcinoma who underwent definitive surgery within 6 months of diagnosis and NAC or NACRT. Overall survival (OS) was compared using the Kaplan-Meier method and logrank test. Multivariable logistic and Cox regressions were used to obtain odds and hazard ratios (OR, HR) adjusted for age, comorbidity, and other patient and tumor characteristics. Results: We identified 2,362 patients treated with NACRT and 658 patients treated with NAC. Median follow-up was 3.9 years. OS modestly favored NAC compared to NACRT (54% vs 51% at 3 years, P = 0.05; adjusted HR 0.86, P = 0.01). Further analysis stratified by the extent of pathological downstaging revealed large separations in the survival curves for both NAC and NACRT according to pathological response (complete, partial/mixed, or none; see table). Patients with no response did equally poorly after either preoperative regimen. NAC was significantly less likely to produce any response than NACRT (adjusted OR 0.62, P < 0.0001). Since NACRT had increased downstaging but not survival, we analyzed use of adjuvant chemotherapy (AC). AC was used significantly less after NACRT than after NAC ( P < 0.0001) (see table). In patients with residual disease in both tumor and lymph nodes, AC was associated with increased OS (47% vs 39% at 3 years, P = 0.05; adjusted HR 0.81, P = 0.07) after NACRT, but not after NAC. Conclusions: NACRT had superior pathological downstaging compared to NAC, but was not associated with increased OS. Adjuvant chemotherapy is relatively underused after NACRT and warrants further study as a risk-adapted means to improve survival, especially in patients with larger burden of residual disease. [Table: see text]