Prognostic relevance of the most predominant and least differentiated grades of gastric adenocarcinoma after curative gastrectomy

Abstract

BackgroundPrognostic relevance of differentiation grade has remained controversial in gastric adenocarcinoma (GAC) after curative resection. MethodsGAC patients who underwent curative gastrectomy were analyzed. Differentiation grade was evaluated according to either the most predominant or least differentiated component. Impacts of clinicopathologic parameters on postoperative recurrence and nodal metastasis were analyzed by the multivariate Cox regression analysis in pT1/2/3/4a and pT1b/2/3 GAC and by the logistic regression analysis in pT1b GAC, respectively. Results154 patients with GAC, consisting of 34 pT1a (recurrence rate 0%), 45 pT1b (4.4%), 18 pT2 (22.2%), 40 pT3 (35.0%), and 17 pT4a (76.5%), were included. In pT1/2/3/4a GAC, recurrence was significantly associated with only depth of invasion (pT) and grade of venous invasion (VI), although either mode of differentiation grade was significantly associated with pT by the Spearman's rank correlation test. Next, given no recurrence in pT1a and high-grade histopathology in nearly all pT4a, pT1b/2/3 GAC was analyzed, revealing that recurrence was significantly associated with only VI grade and nodal metastasis. Finally, nodal metastasis was not found in any pT1a GAC, of which 44.1% was predominantly high-grade. In pT1b GAC, nodal metastasis was irrelevant to either mode of differentiation grade, tumor size, and ulceration status but was only associated with lymphatic invasion, suggesting that endoscopic resection of pT1 GAC with negative margin can be curative even with high-grade histopathology. ConclusionEither mode of differentiation grade revealed limited prognostic relevance after curative gastrectomy. Our results may warrant a controversy over current curability evaluation of endoscopic GAC resection.