[615] Staging of Gastroesophageal Junction Adenocarcinoma with 7th Edition AJCC Staging Manual: Accuracy of Tumor Grade Assessment in Biopsy Specimens.

Johan L Dikken, Daniel G Coit, David S Klimstra, Nabil P Rizk, Nicole van Grieken, David Ilson, Laura H Tang. Memorial Sloan-Kettering Cancer Center, New York, NY; Leiden University Medical Center, Netherlands; Free University, Amsterdam, Netherlands

Background: In the 7th edition of AJCC staging system for esophageal cancer, one of the important changes is the incorporation of histological grade in the stage/prognostic grouping for esophageal carcinoma. For T1-2N0M0 adenocarcinomas, the degree of differentiation is now an independent determinant of stage/prognostic group (Table 1). This study investigated the accuracy of preoperative histopathologic grading and its impact on tumor stage/prognostic grouping.
Design: Preoperative tumor grade was compared to postoperative tumor grade in 427 patients who underwent surgery and without neoadjuvant therapy for esophageal adenocarcinoma. Tumor grade was defined as well (WD), moderately (MD) or poorly differentiated (PD), recording the poorest grade. Cohen's weighted Kappa test for agreement was used as a measurement of accuracy of preoperative tumor grade assessed from biopsies with postoperative stage as gold standard.
Results: The overall accuracy of preoperative tumor grade assessment was 76% (kappa=0.58, p<0.001) including all stages. In patients with T1-2N0 stage tumors, 78% were properly staged (Table 1) with a kappa of 0.47 (P<0.001); However, 16% were assigned to a lower stage group based on preoperative assessment, whereas 7% were assigned a to higher stage group. This resulted in change of AJCC stage/prognostic grouping in 21% of patients (Table 1). In the T1-2N0 group, sensitivity for detecting a PD tumor was 0.55 (CI 0.39-0.70), whereas specificity was 0.89 (CI 0.83-0.96), e.g. of all PD tumors in this group, 45% were misclassified as WD or MD on preoperative biopsies, leading to an estimated lower prognostic stage.

Table 1. Stage Grouping of T1-2N0 Adenocarcinoma with Incorporation of Tumor Differentiation
 Postoperative Stage Grouping
Preoperative Stage Grouping 
IA (T1N0, WD/MD)6413077
IB (T1N0, PD or T2N0, WD/MD)832747
IIA (T2N0, PD)0145

Conclusions: Factors, which could account for discordance in assessment of tumor grade in biopsies and resections, include sampling issue, technical quality of the specimen, and the experience of the pathologists. With increasing use of neoadjuvant therapy, accuracy of preoperative biopsy assessment becomes increasingly important and the interpretation of tumor grade on biopsies should be performed with caution.
Category: Gastrointestinal

Monday, February 28, 2011 1:00 PM

Poster Session II # 92, Monday Afternoon


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