Validation of the 8th edition of the UICC/AJCC staging system for nasopharyngeal carcinoma treated with intensity-modulated radiotherapy

Abstract

An accurate TNM staging system is crucial for treatment guidance and prognosis prediction in nasopharyngeal carcinoma (NPC) patients. In this retrospective study, we evaluated the 8th edition of the Union for International Cancer Control/American Joint Committee on Cancer (UICC/AJCC) staging system for NPC treated with intensity-modulated radiotherapy (IMRT). A total of 608 patients with biopsy-proven, non-metastatic NPC, treated with IMRT between January 2008 and March 2010, were enrolled. The 5-year overall survival (OS), disease-free survival (DFS), local relapse-free survival (LRFS), and distant metastasis-free survival (DMFS) rates were 81.5%, 80.1%, 86.0%, and 81.1%, respectively. The LRFS rates of patients with stages T1 vs. T2, T2 vs. T3, and T1 vs. T3 did not differ between the 7th and 8th editions. By contrast, the DMFS rates of patients with N0 vs. N1, N1 vs. N2, and N2 vs. N3 differed between the 8th and the 7th editions, though no difference was observed between N3a and N3b, according to the 7th edition. The difference in OS between stages II and III, and between stages III and IVa, was larger according to the 8th edition than the 7th edition. There was no difference in the OS between stages I and II. These data indicate that in the IMRT era, the 8th edition staging system can predict the prognosis of NPC patients more accurately than the 7th edition.