Evaluation of 7th Edition of AJCC Staging System for Nasopharyngeal Carcinoma

Purpose: To evaluate and improve the 7th edition International Union against Cancer/American Joint Committee on Cancer staging system for nasopharyngeal carcinoma. Methods: A retrospective review of the data from 905 patients with biopsy-proven non-disseminated nasopharyngeal carcinoma was performed. All the patients were examined by magnetic resonance imaging (MRI) and received radiotherapy. Results: Satisfied distributions among the stages were observed in the 7th edition staging systems. LRFS only differed in classifications betweenT1 and T3, T1 and T4 (P=0.022 and P=0.016, respectively). Significant differences were observed between patients without and with masticator space involvement for OS, DMFS and PFS (p<0.05). No statistically significant differences in LRFS were observed among different groups with anatomical masticator space involvement. The DMFS between N2 and N3b, N3a and N3b were lack of significance (P=0.060 and P=0.59). The T category and N category were independent prognostic factors for the major endpoints in the Cox multivariate regression analysis (P<0.01). Conclusion: This study confirmed the prognostic value of the 7th edition UICC/AJCC staging system, the revisions of the 7th edition staging system are acceptable. However, our study also revealed limitations in the current staging system and suggested some potential modifications in future revision.