Signet Ring Cell Features are Associated with Poor Response to Neoadjuvant Treatment and Dismal Survival in Patients with High-Grade Esophageal Adenocarcinoma.

BACKGROUND While the prognosis of patients with locoregional esophageal adenocarcinoma (EAC) has improved in the neoadjuvant treatment (NAT) era, high-grade histology (G3) is still associated with a limited treatment response. We sought to investigate oncologic outcomes in patients after esophagectomy for G3 EAC and to identify predictors of poor survival among these patients. METHODS Patients with EAC who underwent resection with curative intent in 2011-2018 were divided by histologic grade (G3, G1/2) and compared for overall survival (OS). Cox regression was performed to analyze the response to NAT and the predictive role of signet ring cell (SRC) features. RESULTS The cohort included 163 patients, 94 (57.7%) with G3 histology. NAT was administered to 69 (73.4%) patients. Following resection, OS in the G3 EAC group was 30 months (95% confidence interval [CI] 23.9-36.1). On univariate analysis, G3 disease (p = 0.050) and SRC features (p = 0.019) predicted low OS. Median survival in the G3 EAC group was worse in patients with SRC histology (18 months, 95% CI 8.6-27.4) than those without (30 months, 95% CI 23.8-36.1; p = 0.041). No patients with SRC histology were alive at 5 years of follow-up. Among all patients administered NAT, 88.2% of those with SRC showed minimal or no pathologic response and only 27.8% were downstaged. CONCLUSIONS High-grade histology was found in most patients with EAC and predicted poor survival and treatment response. SRC features in patients with G3 disease were associated with lower OS. The benefit of NAT for G3 EAC in patients with SRC histology appears limited.