Prognostic differences of nasopharyngeal carcinoma patients treated with intensity-modulated radiothe-rapy with different T staging of the seventh and eighth edition of the UICC staging system / 国际肿瘤学杂志

ABSTRACT

Objective:To compare the differences in population distribution and prognosis of patients with nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy (IMRT) in T staging of the Union for International Cancer Control (UICC) 7th edition and UICC 8th edition, and to analyze the prognostic factors in patients with NPC.Methods:The clinicopathologic date of 184 patients with newly diagnosed NPC treated with IMRT at the Department of Radiation Oncology of Weifang People′s Hospital of Shandong Province from June 1, 2005 to December 31, 2017 were retrospectively analyzed. All patients were restaged according to the 7th and 8th edition of the UICC staging system. The distribution of T staging of patients in the two staging systems was analyzed, and the consistency of the two staging systems was compared using the Kappa consistency test. Kaplan-Meier method was used for survival analysis, and log-rank test was used to compare the prognostic differences among T stages. Cox regression model was used to analyze the prognostic factors of patients with NPC.Results:Of all 184 patients with NPC, stage T 1, T 2, T 3 and T 4 respectively accounted for 18.5% (34/184), 16.8% (31/184), 15.2% (28/184) and 49.5% (91/184) according to the 7th edition UICC staging system. However, stage T 1, T 2, T 3 and T 4 respectively accounted for 18.5% (34/184), 34.2% (63/184), 30.4% (56/184) and 16.8% (31/184) according to the 8th edition UICC staging system. The T staging population distribution of the two staging systems showed moderate consistency (Kappa=0.58). There was a statistically significant difference in overall survival (OS) among patients with stage T 1, T 2, T 3, T 4 according to the 7th edition UICC staging system ( χ2=10.606, P=0.014). There were statistically significant differences in OS between stage T 1 and stage T 2, T 3, T 4 ( χ2=4.866, P=0.027; χ2=11.965, P=0.001; χ2=4.351, P=0.037). The OS curves of stage T 2 and T 4 could not be separated. Moreover, the OS curves of stage T 3 and T 4 were distributed in reverse order. There was a statistically significant difference in OS among patients with stage T 1, T 2, T 3, T 4 according to the 8th edition staging system ( χ2=8.663, P=0.034). There were statistically significant differences in OS between stage T 1 and stage T 3, T 4( χ2=8.746, P=0.003; χ2=7.580, P=0.006). The OS curves of stage T 1 to T 4 were distributed in order, but the curves of stage T 3 and T 4 could not be separated. There was a statistically significant difference in progression-free survival (PFS) among patients with stage T 1, T 2, T 3, T 4 according to the 7th edition UICC staging system ( χ2=11.289, P=0.010). There were statistically significant differences in PFS between stage T 1 and stage T 2, T 3, T 4 ( χ2=8.209, P=0.004; χ2=13.302, P<0.001; χ2=6.550, P=0.010). The PFS curves of stage T 2 and T 4 could not be separated. Moreover, the PFS curves of stage T 3 and T 4 were distributed in reverse order. There was a statistically significant difference in PFS among patients with stage T 1, T 2, T 3, T 4 according to the 8th edition staging system ( χ2=12.074, P=0.007). There were statistically significant differences in PFS between stage T 1 and stage T 2, T 3, T 4( χ2=5.182, P=0.023; χ2=11.217, P=0.001; χ2=10.174, P=0.001). The PFS curves of stage T 1 to T 4 were distributed in order, but the curves of stage T 3 and T 4 could not be separated. The results of Cox multivariate analysis showed that T staging of both staging systems were the independent prognostic factors of the OS ( P=0.013; P=0.026) and PFS ( P=0.031; P=0.012). However, T staging of the two editions were not the independent prognostic factors of the local recurrence-free survival (LRFS) ( P=0.351; P=0.167) and distant metastasis-free survival (DMFS) ( P=0.059; P=0.052). The age was the independent prognostic factor of the OS ( HR=2.70, 95% CI 1.53-4.76, P=0.001; HR=2.74, 95% CI 1.55-4.84, P=0.001), PFS ( HR=2.72, 95% CI 1.46-5.08, P=0.002; HR=2.94, 95% CI 1.57-5.52, P=0.001), LRFS ( HR=5.87, 95% CI 1.62-21.27, P=0.007; HR=6.02, 95% CI 1.61-22.49, P=0.008) and DMFS ( HR=2.40, 95% CI 1.22-4.72, P=0.011; HR=2.63, 95% CI 1.34-5.18, P=0.005). N staging was the independent prognostic factor of the OS ( P=0.031; P=0.028). Conclusion:The T staging population distribution of the 7th and 8th edition UICC staging system had moderate consistency, and the T staging of the 8th edition is more advantageous in predicting the prognosis of OS and PFS. In both editions, T staging is an independent prognostic factor for OS and PFS.