Study on N staging system for nasopharyngeal carcinoma based on intensity-modulated radiotherapy and RTOG guidelines for cervical lymph node levels / 中华放射肿瘤学杂志

ABSTRACT

Objective To propose a new N staging system for nasopharyngeal carcinoma based on intensity-modulated radiotherapy (IMRT) and Radiation Therapy Oncology Group (RTOG) guidelines for cervical lymph node levels.Methods A retrospective analysis was performed in 324 patients with newly diagnosed nasopharyngeal carcinoma who had no distant metastasis confirmed by pathology and received IMRT in the Department of Radiation Oncology in The First Affiliated Hospital of Guangxi Medical University from January 2010 to December 2011.They were restaged according to the 7thedition of UICC/AJCC staging system for nasopharyngeal carcinoma.The survival rates were estimated using the Kaplan-Meier method and the log-rank test was used for univariate prognostic analysis.The Cox proportional hazards model was used for multivariate prognostic analysis.Results Of 324 patients,269(83.0%) had lymph node metastasis.The median follow-up was 58 months (6-77 months).The 5-year overall survival,disease-free survival,relapse-free survival,and distant metastasis-free survival rates were 84.8%,77.1%,92.7%,and 80.5%,respectively.Univariate and multivariate analyses of patients with positive cervical lymph nodes revealed that retropharyngeal lymph node status,cervical lymph node level,and laterality were evaluated as independent prognostic factors for nasopharyngeal carcinoma.According to the hazard ratio calculated,the N staging system was revised as followsN0no regional lymph node metastasis;N1VⅡ a or/and unilateral levels (I,Ⅱ,Ⅲ,Va) involvement;N2bilateral levels (I,Ⅱ,Ⅲ,Va) involvement;N3levels IVa,Vb,and IVb+Vc involvement.Conclusions The proposed N staging system is based on IMRT and RTOG guidelines for lymph node levels and more practical,and can provide highly objective prediction of outcome and guide treatment in nasopharyngeal carcinoma.