Prognostic factors on patients with clinically node-negative nasopharyngeal carcinoma after radiotherapy

OBJECTIVE:To evaluate the outcomes of patients with N0 nasopharyngeal carcinoma(NPC)treated primarily by external beam irradiation,and explore the prognostic factors.METHODS:A total of 627 patients with N0 NPC undergoing radiotherapy from May 1,1989 to December 31,2009 were retrospectively analyzed.Computed tomography(CT)scans of the primary lesion were performed to every patient.All patients received definitive radiotherapy with 60 Coγor 6MV X rays using conventional fraction at 2Gy daily,5fractions per week.The accumulated survival was calculated according to the Kaplan-Meier method.Log-rank test was used to compare the survival difference.Cox proportional hazards model was used for multivariate analysis.RESULTS:The 5-year and 10-year actuarial overall survival,disease-free survival,disease-specific survival,local failure-free survival,regional failure-free survival,locoregional failure-free survival,and distant metastasis-free survival rates were 78.6% and 66.6%,68.9% and 55.9%,79.9% and 70.3%,81.4% and72.8%,95.9%and 91.9%,78.5% and 68.8%,88.4% and 85.2%,respectively.Local recurrence,regional relapse and distant metastases as the first event of treatment failure occurred in 104(104/627,16.6%),15(15/627,2.4%)and 54cases(54/627,8.6%),respectively.Multivariate analysis showed that T stage was the only independent prognostic factor for overall survival.Male,late T stage and anemia were the factors adversely affect disease-free survival.CONCLUSIONS:Satisfactory treatment outcomes have been achieved in patients with N0 NPC.Local recurrence represents the predominant mode of treatment failure.T stage is the only independent prognostic factor for overall survival.Male,T stage and anemia are the independent prognostic factors for disease-free survival.