RA09.02: LYMPH NODE RESPONSE AFTER NEOADJUVANT CHEMORADIATION THERAPY FOR ESOPHAGEAL ADENOCARCINOMA: TIME FOR AN APPROPRIATE YPN CLASSIFICATION

Abstract

Abstract Background Response of the primary tumor and lymph node involvement are the most important prognosticators in resected patients with esophageal adenocarcinoma after neoadjuvant chemoradiation. Response on the primary tumor is well established using T(umor) R(egression) G(rading). However, little is known about the prognostic value of lymph node response in these patients. Methods Hematoxylin-eosin slides of 193 adenocarcinoma patients with clinical suspicion of lymph node involvement (cN+) and treated with neoadjuvant chemoradiation therapy between 2008 and 2015 were all reassessed by a senior pathologist. Lymph node response (LNR) was defined as a combination of central fibrosis and at least one other characteristic such as hemosiderin pigment, acellular mucin pools, foam cells, giant cells or calcifications. Lymph nodes were categorized in four categories: 1° as positive (ypN+) when viable tumor was found according to TNM 8th edition. 2° as negative (ypN0) in absence of any viable tumor. 3° as lymph nodes with signs of LNR (LNR+). 4° as lymph nodes without signs of LNR (LNR-). All patients were grouped according to lymph node positivity and lymph node regression. Multivariate and survival analysis were performed by Cox proportional hazard regression analysis. Results Thirty-four patients were ypN + /LNR + , 60 were ypN + /LNR-, 41 were ypN0/LNR + and 58 were ypN0/LNR-. Median overall survival was respectively 41.0 months, 18.5 months, 31.2 months and 62.9 months. Survival was significantly different between ypN0 groups (P = 0.045) but not between ypN + groups (P = 0.299). Multivariate analysis showed that LNR was an independent prognosticator (P = 0.011). Conclusion In cN + esophageal adenocarcinoma patients treated with neoadjuvant chemoradiation with final pathology being ypN0 after esophagectomy, median overall survival is doubled when no signs of LNR were found suggesting these patients were in fact true N0 and that ypN0/LNR + have a similar prognosis as ypN + /LNR + . Using these four categories of ypN allows for more precise evaluation of the impact of induction therapy. Disclosure All authors have declared no conflicts of interest.