E450: The Influence of Lymph Node Ratio on Survival in Gastric Adenocarcinoma Patients Following Radical Gastrectomy

Introduction: Limitations of the TNM N stage become evident with insufficient lymph node resection. The lymph node ratio (LNR), which combines metastatic to total nodes dissected, is a metric that reflects quality of oncologic resection. This study examines LNR's association with survival outcomes

Methods: Retrospective study of patients diagnosed with gastric adenocarcinoma who underwent oncologic resection at a single center between 2015 and 2018. The LNR was calculated as the ratio of affected lymph nodes to the total dissected during gastrectomy. Perioperative characteristics were comparatively assessed based on LNR quartiles as follow LNR0: 0, LNR 1: >0- 0.16, LNR 2: >0.16- 0.4 y LNR3: > 0.4. To capture any non-linear associations between LNR and outcomes, we used restricted cubic splines (RCS). Kaplan-Meier survival curves and multivariable Cox regression models were used to evaluate the association between LNR and longitudinal survival, adjusting for the total number of N

Results: We included a total of 157 patients with a median age of 64 years, 36.9% (n= 58) women. Overall, 74.5% (n=117) were categorized as ECOG 1, 43.9% (n= 69) as clinical TNM III stage. The median number of lymph nodes collected was 24, with the majority (77%, n=122) of the patients having more than 15 lymph nodes. The median number of positive lymph nodes (N+) was 3N. Clinical differences between groups were evidenced (Figure).

Overall survival and disease-free survival curves were different between the groups As LNR increased, we observed a marked decline in both (p=0.0010) (Figure). The RCS showed a positive inflection in the HR for mortality starting from a LNR greater than 40% compared to those who had 0% involvement. This means that patients with 40% involvement had up to twice the hazard of mortality (HR 2.13, 95% CI 1.02-4.48) than patients without lymph node involvement. In terms of recurrence, patients with 10% LNR involvement had up to three times the risk of recurrence (HR 3.12, 95% CI 1.1-8.82) than patients without lymph node involvement after multivariable adjustment, including the total number of lymph nodes resected

Conclusions: The lymph node ratio (LNR) shows to be an independent prognostic factor for survival outcomes following radical gastrectomy. An LNR threshold of 40% appears to be a critical marker for mortality hazard, while even a 10% LNR is associated with higher recurrence risk after controlling for covariates. This study underscores the importance of LNR incorporation in risk stratification as a comprehensive indicator, particularly in settings with limited access to standardized oncologic surgery