A prognostic model based on lymph node metastatic ratio for predicting survival outcome in gastric cancer patients with N3b subclassification

Background: Determining the survival outcome for gastric cancer patients with metastases to more than 15 regional lymph nodes is difficult. This study aims to develop a lymph node metastatic ratio (LNR)-based prognostic model to predict the survival outcome after D2 surgery in such patient groups. Methods: Our study retrospectively enrolled 139 gastric cancer patients with metastases to more than 15 regional lymph nodes who underwent D2 surgery between 2007 and 2014. Clinicopathologic variables to predict overall survival (OS) using multivariate Cox regression were selected to create a prognostic model. Results: The prognostic model for predicting OS was developed based on five independent factors, namely, T-classification (T2 or T3 vs. T4), LNR (<0.80 vs. ≥0.80), carcinoembryonic antigen level (<5 vs. ≥5 ng/ml), Eastern Cooperative Oncology Group performance scale (scale 0–1 vs. ≥2), and adjuvant chemotherapy (yes vs. no). Using the prognostic score, patients were stratified into good, intermediate, and poor prognostic groups. The median OS in the good, intermediate, and poor prognostic risk groups was 32.0 months (95% confidence interval [CI]: 22.3–41.7), 12.4 months (95% CI: 8.5–16.3), and 5.4 months (95% CI: 2.1–8.7), respectively. The c-index of the prognostic model was 0.79 (95% CI: 0.71–0.87). Conclusion: This study developed an accurate LNR-based prognostic model for predicting the survival outcome after D2 surgery in gastric cancer patients with metastasis to more than 15 regional lymph nodes. This model might assist clinicians in prognostic stratification of such patients and convince eligible patients to receive adjuvant chemotherapy.