Value of Post-NAC CT-based Node-RADS score for Predicting residual lymph node metastasis and survival outcome of locally advanced gastric cancer.

[OBJECTIVES] The Node Reporting and Data System (Node-RADS) provides structured and effective evaluation for lymph nodes in malignancies. This study aims to investigate its value in predicting residual lymph node metastasis (LNM) and survival outcome of locally advanced gastric cancer (LAGC).

[MATERIALS AND METHODS] This retrospective study included 118 patients with LAGC underwent neoadjuvant chemotherapy (NAC) and gastrectomy from April 2015 to June 2020. The diagnostic performance of the post-NAC CT-based Node-RADS score for regional LNM, both at the patient level and at the perigastric/extragastric subgroup level, was estimated using area under receiver operating characteristic curve (AUC) and Youden's index. Kaplan-Meier curve was employed for prognostic analyses between high/low Node-RADS score group. A predictive Node-RADS (NR) model for LNM was developed using logistic regression analyses and a prognostic NR model for overall survival (OS) was developed using Cox regression analyses.

[RESULTS] In the prediction of LNM, the Node-RADS score exhibited an AUC of 0.843 (95%CI: 0.765-0.921) at patient level, 0.838 (95%CI: 0.757-0.918) in perigastric subgroup and 0.813 (95%CI: 0.724-0.901) in extragastric subgroup, surpassing LN short-axis criteria (AUC:0.664 [95%CI: 0.584-0.743], p < 0.001). The AUC of the NR predictive model for LNM increased to 0.870 (95%CI: 0.795-0.945), with 88.7% sensitivity and 78.9% specificity. The Node-RADS score was significantly correlated with post-NAC pathological status, and served as an independent indicator for OS (all p < 0.05).The NR prognostic model exhibited a Harrell's consistency index (C-index) of 0.724 (95%CI: 0.663-0.785), with no significant difference from the pathological prognostic model (0.739 [95%CI: 0.677-0.801], p = 0.695).

[CONCLUSION] The post-NAC Node-RADS score provides accurate prediction of regional LNM and shows promising prognostic value for LAGC patients. Post-NAC Node-RADS related predictive models show potential in early identification of high-risk LAGC patients with residual lymph nodes or poor prognosis after NAC.