Modified pathological N2 staging system in prognosis predicting of penile cancer patients

OBJECTIVE:To determined whether the pathological N2 staging system of Union for International Cancer Control-American Joint Committee on Cancer(UICC-AJCC),which divided into pN2a and pN2b,leads to more specific prediction of survival for patients with penile cancer.METHODS:The case records of 153patients with penile cancer who underwent inguinal lymphadenectomy between 2002and 2012were analyzed.pN2patients were divided into 2groups and they were multiple inguinal lymph nodes metastasis group and bilateral inguinal lymph nodes metastasis group,according to pathological information on the lymph node metastasis laterality.The survival was analyzed by Kaplan-Meier and Logrank test.Predictive accuracy was assessed by Logistic and the criteria was investigated to evaluate the prognostic models with chi-square,AIC and the Harrell c-index.RESULTS:Totally 71patients were proved to be lymph node metastasis. The median number of LNs removed was 22(range 5-53nodes).There were 21(29.6%),33(46.5%),17(23.9%)patients exhibited pN1,pN2,pN3,respectively.The 3-year disease specific survival(DSS)was 94.4%,69.6%,27.2% for pN 1,pN 2 and pN 3 disease respectively.In this group of patients,19(57.6%)had pN 2a disease,and 14(42.4%)had pN 2b disease.The 3-year DSS for pN2a,pN2b disease was 84.7%and 50.1%,respectively.Better survival stratification was observed on analysis(P=0.034).Adding lymph node metastasis laterality significantly increased the accuracy of the pathological 7th N2 category to improve prognostication and predict cancer specific survival.CONCLUSIONS:The modified pathological N2 staging system is proved to be a significantly better prognosticator of DSS than the current pathological N2 staging system in patients with penile cancer.Further independent validation is required to determine the clinical usefulness of new pathological N staging system in these patients.