Tumor differentiation impacts response to neoadjuvant therapy and survival in patients with esophageal adenocarcinoma

Objective: The current staging system for esophageal adenocarcinoma only considers tumor grade in early tumors. The aim of this study was to evaluate the impact of tumor differentiation on response to neoadjuvant chemoradiotherapy and survival in patients with locally advanced esophageal adenocarcinoma. Methods: This was a multi-institution retrospective review of all patients with esophageal cancer who underwent neoadjuvant chemoradiotherapy followed by esophagectomy from January 2010 to December 2017. Response to neoadjuvant therapy and survival was compared between patients with well- or moderately differentiated (G1/2) tumors versus poorly differentiated (G3) tumors. Results: There were 550 patients, 485 men (88.2%) and 65 women. The median age was 61 years, and the tumor was G1/2 in 288 (52.4%) and G3 in 262 patients. Overall clinical stage before neoadjuvant therapy was similar between groups. Pathologic complete response (pCR) was found in 87 patients (15.8%). The frequency of pCR was similar between groups, but residual disease in the esophagus and lymph nodes was significantly more likely with G3 tumors. Median follow-up was 63 months and absolute survival, overall survival, and disease-free survival were all significantly worse in patients with G3 tumors. Further, even with pCR, patients with G3 tumors had significantly worse survival. Conclusions: This study showed that response to neoadjuvant therapy was not affected by tumor differentiation. However, poor differentiation was associated with worse survival compared with patients with G1/2 tumors, even among those with pCR. These results suggest that poor differentiation should be considered as an added risk factor for clinical staging in patients with locally advanced esophageal adenocarcinoma.