Prognostic Significance of Metastatic Lymph Node Ratio in Patients with Gastric Cancer: an Evaluation in North-East of Iran

BACKGROUND: In this study we have evaluated the prognostic impact of Metastatic Lymph node Ratio (MLR) in gastric cancer patients whose have undergone curative surgical resection. METHODS: A total of 121 patients with gastric adenocarcinoma undergoing curative surgical resection (R0) in our institutions between 2003 and 2010 have been included in this study. MLR has classified into 3 groups as follows: MLR0; 0, MLR1; >0-0.33 and MLR2; 0.34-1. We have used Kaplan-Meier method to calculate survival rates and log rank test to compare survival curves between groups. Cox proportional hazards model has utilized for multivariate analysis. RESULTS: The median age of patients was 65 (range; 32 to 89) with a male to female ratio of 91/30 (3.03). 88 patients have undergone total gastrectomy (72.5%) and 33 subtotal gastrectomy (27.5%). With a median total retrieved lymph node of 11 (range; 6 to 44), the MLR0 to MLR2 has calculated in 28(23.1%), 31(25.6%) and 62 (51.2%) patients respectively. MLR2 (>0.33) has significantly associated with higher Tumor stage (T1-T2: 18.7% vs. T3: 56.2%, p=0.002). With a median follow up time of 12 months (range; 2-88), the 3-year survival in patients with MLR0, MLR1 and MLR2 was 75.1%, 54.8% and 9.5% respectively (p value<0.001). Tumor location (p<0.01), tumor stage (p<0.01) and lymph node stage (p<0.001) were also significant predictor of survival. MLR has also significant correlated with survival in 91 patients with less than 15 obtained lymph nodes (p<0.001). Cox-regression multivariate analysis has shown MLR as the most important and independent predictor of survival (p<0.001). CONCLUSION: MLR with cutoff point of 0.33 could be used as an independent prognostic factor in gastric cancer patients whose have undergone curative surgical resection. This factor could effectively predict survival even in cases with insufficient (<15) retrieved lymph nodes.