Comparison Of Three Lymph Node Staging Systems For Survival Prediction In Advanced Gastric Cancer

Objective To compare the prognostic accuracy of the metastasis lymph node number(pN),lymph node metastasis rate(rN)and log odds of positive lymph nodes(LODDS)staging system in advanced gastric cancer(AGC),and to provide the basis for rational lymph node(LN)staging,prognosis evaluation and postoperative adjuvant therapy.Methods Clinical and pathological data of 175 patients who underwent gastric cancer radical resection with complete follow-up information from January 2010 to June 2010 at the Affiliated People's Hospital of Fujian University of Traditional Chinese Medicine were retrospectively analyzed.(1)Kaplan-Meier method was used to calculate the postoperative survival rate of AGC patients and draw the survival curve;the comparison of survival rates between groups was performed using Log-rank test;Univariate analysis of statistically significant factors was included in the Cox proportional hazards regression model to determine the independent factors influencing postoperative prognosis of AGC.(2)The homogeneity of 3-year survival rate(3-YSR)across each pN staging within each rN and LODDS staging was compared by using the log-rank test.(3)The homogeneity of different LN staging systems was compared by the likelihood ratio x2 test.The linear trend x2 test was used to compare the discrimination,the singularity between staging and prognosis of different LN staging systems.The Cox proportional hazards model was used to calculate the-21og likelihood of different LN staging systems.The Akaike information criterion(AIC)values of different LN staging systems were further calculated to compare the accuracy of the prognosis.(4)Receiver Operating Characteristic curve(ROC)and area under the curve(AUC)were compared to evaluate the prognosis of different LN staging systems.(5)All statistical analyses were performed using SPSS 20.0 and MedCalc 15.2.2.A value of P<0.05 indicated statistical significance.Results(1)The 3-year survival rates(3-YSR)of pN0,pN1,pN2 and pN3 were 76.6%?70.4%?47.1%and 29.2%,respectively;The 3-YSR of rN0,rN1,rN2 and rN3 were 79.2%,64.0%,20.8%and 0,respectively;the 3-YSR of LODDS1,LODDS2,LODDS3,LODDS4 and LODDS5 were 92.3%,74.3%,60.1%,41.7%and 7.8%,respectively.(2)Log-Rank analysis showed that tumor diameter,Borrmann type,pathologic type,tumor thrombus,infiltration degree,TNM staging,pN staging,rN staging and LODDS staging were correlated with prognosis of AGC(all P<0.05).Further multivariate Cox proportional hazards regression analysis showed that pathological type(HR=1.998,P=0.025),rN staging(HR=1.876,P=0.007)and LODDS staging(HR=1.694,P<0.001)are independent prognostic factors in AGC.(3)Both the rN and LODDS staging systems showed better discrimination of prognostic risks in patients of the same positive pN staging.However,the LODDS staging system could also efficiently discriminate the survival probabilities of patients with no positivenodes(pN0),while rN staging system could not.In contrast,pN staging system was not able to further discriminate the prognosis of AGC patients in the same pN and LODDS stagings.(4)The linear trend x2 test scorcs and likelihood ratio x2 test scores(46.513 and 62.380)of rN staging system were higher than pN(27.950 and 31.612)and LODDS staging systems(42.367 and 59.900),while the AIC values(688.692)was lower than pN(719.460)and LODDS staging systems(693.172).(5)In patients with postoperative 3 years death or not as the gold standard,the area under the ROC curve(AUC)of the pN staging system was 0.726(95%CI:0.653 to 0.790),the rN staging system was 0.774(95%CI:0.705 to 0.834),and LODDS was 0.781(95%CI:0.712-0.840);there was a significant difference in the AUC between pN and rN staging systems(P=0.033),but no statistical difference between pN and LODDS staging system,rN and LODDS staging system(P>0.05).Conclusion rN and LODDS staging were independent prognostic risk factors of AGC patients,in assessing the prognostic accuracy of AGC patients,rN staging system is more superior than LODDS and pN staging systems;In clinical work,the rN staging system can be included as an independent indicator to evaluate the prognosis of AGC patients.