Preoperative accuracy of gastric cancer staging in patient selection for neoadjuvant therapy.

Abstract

34 Background: Because gastric cancers stage ≥ T2 or ≥ N1 are considered for neoadjuvant treatment, accuracy of preoperative staging is critical. The purpose of this study was to identify preoperative staging accuracies of computed tomography scan (CT) and endoscopic ultrasound (EUS) in gastric cancer and their utilities in selecting patients for neoadjuvant therapy. Methods: Medical records of 8,260 patients with gastric or gastroesophageal adenocarcinoma (presented 1995-2013) were reviewed to identify those who underwent gastrectomy but not neoadjuvant treatment. We reviewed preoperative EUS reports and CT images to identify detailed T stage (based on AJCC 7thedition) and lymph node positivity (short axis diameter ≥ 6mm). T stage and N status were compared with those from the surgical pathology report. Clinicopathologic variables associated with incorrect preoperative staging were also examined. Results: We identified 187 patients who underwent preoperative staging by EUS (n = 145) and/or CT (n = 134) for gastrectomy. The accuracy, sensitivity, and specificity of EUS in distinguishing T1 from more advanced tumors were 82%, 78%, and 85%, respectively. In univariate analysis, tumor location and lymphovascular invasion were associated with incorrect EUS T staging. In multivariate analysis, variables associated with underestimation of EUS T stage was lymphovascular invasion (OR 7.51, 95% CI 1.91-29.5, p < 0.01) and Caucasian race (OR 3.75, 95% CI 1.31-10.75, p = 0.01). The accuracies, sensitivities, and specificities for N status were, respectively, 65%, 49%, and 79% with CT and 66%, 29%, and 95% with EUS. In univariate analysis, poor differentiation and lymphovascular invasion were associated with incorrect diagnosis of CT N status. In multivariate analysis, lymphovascular invasion was associated with false-negative (OR 3.79, 95% CI 1.34-10.7, p = 0.01), and differentiated histology was associated with false-positive CT N status (OR 7.14, 95% CI 2.00-25.44, p < 0.01). Conclusions: EUS has reasonable accuracy in T stage, while both CT and EUS have low sensitivities and high specificities in N status. These accuracies should be considered when selecting patients for neoadjuvant treatment.