Comparison of the Chinese'92 and 2008 staging systems of nasopharyngeal carcinoma according to the long term outcomes of patients treated with intensity-modulated radiotherapy / 中华放射肿瘤学杂志

ABSTRACT

Objective To compare the Chinese'92 and 2008 staging systems of nasopharyngeal carcinoma (NPC) based on the long term survival of the patients. Methods Clinical data of 498 NPC patients treated with definitive IMRT were retrospectively analyzed. The distributions of patients in the two staging systems were compared. The long term outcomes according to T, N and overall stages in each system were evaluated. Kappa value and Pearson coefficient were used to evaluate the agreement and correlation of the two systems. Results The distributions of both T and N stage between'92 and 2008 stage systems were different. In both staging systems, the local recurrence-free survival (LRFS) curves of T_1, T_2 andT_3 were close up (even overlaped), though they were apart from T_4. The distant metastasis-free survival (DMFS) curves overlaped of N_1 and N_2 in the'92 staging system, while separated of N_1, N_2 and N_3 in the 2008 staging system. Significant difference of DMFS was not found between N, and N_2 in'92 staging system, while did exist among N_0, N_1, N_2 and N_3 stages in 2008 staging system. In the both staging systems, the disease-specific survival (DSS) of stage Ⅰ did not significantly differ from that of stage Ⅱ or Ⅲ. The statistical analysis showed the conformality of DSS curves in the two system was 89% (Kappa =0. 833 ,P <0.01), with agood relative rate (r=0. 919,P<0. 01). Conclusions The difference between'92 and 2008 staging system is mainly in N stage. The 2008 N stage seems more reasonable compared with'92 N stage, which is able to better forecast the DMFS. There are some agreements and correlations between the two staging systems.