Background: It is known that ypN0 status after induction treatment can be divided into "natural" N0 (cN0/ypN0) and "downstaged" N0 (cN+/ypN0). Whether natural N0 patients and downstaged N0 patients with esophageal squamous cell carcinoma (ESCC) after neoadjvant chemoradiotherapy (nCRT) have similar prognosis is unknown.
Methods: An institutional database was reviewed to identify ESCC patients after nCRT, whose CT scans were retrieved and reviewed to reclassify nodal status. The patients were divided into 3 groups based on node status: natural N0, downstaged N0, and ypN+. Impact of nodal status on survival and associations with survival were analyzed.
Results: We identified 110 patients, and 25 had natural N0 disease, 52 had downstaged N0 disease, and 33 had ypN+ disease. The 3-year OS was 76.7%, 79.5%, and 49% in natural N0, downstaged N0 and ypN+ group, respectively, and, correspondingly, the 3-year DFS was 77%, 73.9%, and 36.3%. In multivariable analysis, OS (P = 0.794) and DFS (P = 0.957) did not differ between natural N0 and downstaged N0 groups, but it was significantly shorter in ypN+ group (OS, P = 0.032; DFS, P = 0.021). In subgroups with "poor response" of primary tumor, the prognosis of natural N0 and downstaged N0 paitents was poor almost identical to ypN+ in both OS (P = 0.721; P = 0.252) and DFS (P = 0.694; P = 0.114).
Conclusions: The ypN0 status is an important hallmark demonstrating the effectiveness of nCRT for ESCC, regardless of cN status. Additionally, the survival of natural N0 and downstaged N0 patients with bad response at primary site may be poor, similar to ypN+ patients.
Keywords: Esophageal squamous cell carcinoma; Neoadjuvant chemoradiotherapy; Nodal downstaging; Survival.