Background & objective: On the basis of our previous research, this study was to validate the rationality of AJCC/UICC staging system (1997) of nasopharyngeal carcinoma (NPC), and to provide some suggestions.
Methods: Survival data of 915 NPC patients, received radical radiotherapy alone in Cancer Center of Sun Yat-sen University from Jan. 1997 to Dec. 1998, were analyzed with Life table, Cox regression, Kaplan-Meier, and log-rank methods.
Results: Cox regression analysis showed that the 5-year survival rate of the 915 patients was significantly correlated to their age and tumor stage classified according to AJCC/UICC (1997) staging system; while that of the 803 patients no more than 60 years old was only significantly correlated to tumor stage. Life table analysis validated that the tumor stage classified according to AJCC/UICC staging system can roughly predict the prognosis, but the differences between stage I and IIa, or IVa and IVb were not significant. Kaplan-Meier analysis showed no significant differences of survival rate between stage T1 and T2a, or T3 and T4 when adjusted by N classification, and between stage N2 and N3a, or N3a and N3b when adjusted by T classification. Therefore, we adjusted stage T2a to T1, stage N1 with inferior cervical nodes metastasis to N2, combined stage N3a and N3b to N3, adjusted stage IIa to I, stage IIb to II, and stage IVb to IVa. After the modifications, the differences among stages I-IVa, T1-T4 (adjusted by N classification) and N0-N3 (adjusted by T classification) were significant.
Conclusion: Taking the impact of age on the prognosis and the interaction between T stage and N stage into consideration, the above modifications should be included when renewing the AJCC/UICC staging system (1997).