External validation of the eCura system and comparison with the W-eCura score for predicting lymph node metastasis after non-curative endoscopic submucosal dissection for early gastric cancer: a multicenter retrospective cohort study

Abstract

Background: The eCura system is a widely used risk-scoring model for predicting lymph node metastasis (LNM) after non-curative endoscopic submucosal dissection (ESD) for early gastric cancer (EGC), but its external validation is limited. Recently, the W-eCura score, a modified version, was proposed. We aimed to validate the eCura system and compare its discriminatory performance with the W-eCura score.

Methods: A multicenter retrospective study was conducted using data from 19 Japanese institutions. The patients who underwent ESD for EGC followed by gastrectomy with lymph node dissection were included. The predictive performance of the eCura system, including calibration and discrimination, was evaluated and its discrimination was compared with the W-eCura score.

Results: Among 901 eligible patients, 65 cases (7.2%) showed LNM. The eCura system demonstrated good calibration, with a calibration-in-the-large of -0.008 (95% confidence interval [CI] -0.024-0.010), an observed-to-expected ratio of 0.905 (95% CI 0.707-1.121), and a calibration slope of 0.975 (95% CI 0.692-1.257). Discrimination was also good, with a C-statistic of 0.741 (95% CI 0.676-0.806). In patients evaluable for both systems, the C-statistics for the eCura system and W-eCura score were 0.745 (95% CI 0.675-0.816) and 0.750 (95% CI 0.684-0.817), respectively, showing no significant difference (P = 0.547).

Conclusions: The eCura system was validated as a reliable tool for predicting LNM following ESD in real-world clinical settings.

Keywords: Early gastric cancer; Endoscopic submucosal dissection; Lymph node metastasis; Validation study; eCura system.