Lymph Node Metastasis Rate In The Application Of N Staging Gastric Cancer

Background:Depth of tumor invasion (T-category) and the number ofmetastatic lymph nodes (N-category，pN) are the most importantprognostic factors in patients with gastric cancer. Recently,the ratio between metastatic and dissected lymph nodes (N-ratio，rN) has been established as one. The aim of this studyis to evaluate the impact of N-ratio and its interaction withN-category as a prognostic factor in gastric cancer.Methods:We reviewed clinical and pathological data of165patientswho had undergone curative surgery at our institution betweenSeptember2005and March2007. The exclusion criteria includedmetastases, gastric stump tumors and gastrectomy with less than15lymph nodes dissected.Results:The median age of the patients was63years and54.5%of themwere male. Subtotal gastrectomy was the most common procedureand92.1%of the patients had a D2-lymphadenectomy. Their5-year overall survival was57.7%. T-category, N-category, andN-ratio were prognostic factors in overall and disease-freesurvival in accordance with univariate analysis. In accordance with TNM staging, pN1patients who have had rN1had5-yearsurvival in75.5%whereas in the rN2group only33%of the caseshad5-year survival. In the multivariate analysis, theinteraction between N-category and N-ratio was an independentprognostic factor.Conclusion:Our findings confirmed the role of N-ratio as prognosticfactor of survival in patients with gastric cancer surgicallytreated with at least15lymph nodes dissected.The rN stagingmethod can reduces the rate of “stage migration”， therelationship between N-category and N-ratio is a betterpredictor than lymph node metastasis staging.