Differential Impact Of Systemic Lymphadenectomy Upon The Survival Of Patients With Type ? V.s.type ? Endometrial Cancer: A Retrospective Observational Cohort Study

Objectives.To determine whether systemic lymphadenectomy exerts similar effect on the survival of patients with either type I or type II endometrial cancer(EC).Methods.From May,2011 to May,2017,682 eligible patients in the First Affiliated Hospital of Chongqing Medical University,pathologically diagnosed with EC,were analyzed retrospectively.Type I EC is pathologically defined as the International Federation of Gynecology and Obstetrics(FIGO)grade 1/2 endometrioid adenocarcinoma while type II EC,the FIGO grade 3 endometrioid adenocarcinoma or non-endometrioid endometrial carcinoma.The thoroughness of the lymphadenectomy is evaluated through the number of dissected lymph nodes,of which the cut-off value is detected through the maximal area under the Receiver operator characteristic(ROC)curve with Youden index.The impact of thoroughness on survival of type I,type II,or both types,was analyzed respectively by Kaplan-Meier method(K-M method),so as other clinical or pathological factors possibly contributing to the survival.The independent prognostic factors of survival are selected by the proportional hazard regression model(COX model).Results.Through ROC curve and Youden index,the cut-off level was determined as 20.Although the role of the lymph node number removed inthe survival of patients could not be observed if all patients with EC analyzed as a total,differential impact was noted if patients with different types were analyzed separately: Among patients with type I EC(519 cases,76.1%),those with >20 and ?20 lymph nodes removed have similar overall survival(OS)(p = 0.759).Among patients with type II EC(163 cases,23.9%),those with >20 lymph nodes removed presented better OS than those with?20(p=0.002).The number of lymph node removed >20 was proved an independent factor for improved OS in patients with type II EC(HR=0.366,95%CI:0.166-0.810,p =0.013).Additionally,in those type II EC patients with >20 lymph nodes resected,similar overall 5-year survival rate was observed with or without identified positive node(90.9% v.s.92.9%,p=0.965).Conclusions.Systemic lymphadenectomy could enhance the OS of type II EC other than type I EC patients.