Retrospective comparison of the AJCC 5th edition classification for nasopharyngeal carcinoma with the AJCC 4th edition: an experience in Taiwan

Objective: The aim of this study was to compare the new AJCC 5th edition cl assification system for nasopharyngeal carcinoma (NPC) with the AJCC 4th ed ition by re-evaluating the staging of patients treated in Taiwan. Methods: From 1992 through 1996, 117 NPC patients without distant metastasi s were treated using complete courses of radiotherapy. All patients had com plete CT examinations of the nasopharynx and neck. Each patient was re-stag ed according to the 5th edition of the AJCC classification system. Their ov erall survival (OS), loco-regional relapse-free survival (LRRFS), distant m etastasis-free survival (DMFS) and disease-free survival (DFS) were compare d between the two staging systems, using the Kaplan-Meier method, log-rank test, Wilcoxon test and Cox proportional hazard model. Results: After a median follow-up of 58.3 months, the 5-year OS for stage I , II, III and IV was 88, 86, 61 and 48%, respectively, according to the new staging. A more even distribution of patients was noted among the patients classified according to the AJCC 5th edition than the 4th edition. The dis tribution of stages I, II, III and IV was 13.7, 37.6, 15.4 and 33.3%, respe ctively, using the new staging system, whereas it was 0.8, 14.5, 20.5 and 6 4.2%, respectively, using the old staging system. More statistically signif icant differences among 5th edition stages and T classifications than the 4 th edition were also noted. Conclusions: The 5th edition of the AJCC staging system appears to have a m ore even distribution of patients and more statistically significant differ ences in predicting prognosis than the 4th edition, mostly in stages and T classification.