Benefit of adjuvant chemotherapy based on lymph node involvement for oesophageal cancer following trimodality therapy

BACKGROUND: Oesophageal cancer (OC) survival rates have improved since the widespread adoption of neoadjuvant chemoradiation therapy (NACRT) followed by oesophagectomy (trimodality therapy). Unfortunately, the overall prognosis for patients with locally advanced disease remains poor. In this study, we sought to assess the effect of adjuvant chemotherapy (AC) in patients treated with trimodality therapy. METHODS: Using the National Cancer Database we retrospectively identified 6785 patients with locally advanced (cT1b-T4a, N0-N+, M0) OC who were treated with trimodality therapy from 2006 to 2014. Patients were separated based on receipt of AC (n=463), as well as clinical and pathological lymph node involvement. Overall survival (OS) between groups was compared using the Kaplan-Meier method and Cox proportional hazard modelling. RESULTS: Based on multivariate analysis, AC was associated with a statistically significantly reduced risk of death (HR 0.77, p<0.001). Subgroup analysis revealed that AC was associated with reduced risk of death compared with NACRT alone in the cN+/pN0 (median OS 64 vs 43 months; p=0.019) and the cN+/pN+ (median OS 27 vs 22 months; p=0.010) groups, but not in the cN0/pN0 (median OS 48 vs 49 months; p=0.253) or cN0/pN+ (median OS 31 vs 24 months; p=0.077) groups. CONCLUSION: AC following trimodality therapy may improve survival in patients with locally advanced OC. Patients who undergo lymph node downstaging may be the most likely to benefit from AC. Prospective studies are needed to confirm this finding.