Li-Rong Wu1, Xiu-Ming Zhang2, Xiao-Dong Xie2, Yue Lu1, Jian-Feng Wu1, Xia He3. 1. Department of Radiation Oncology, Jiangsu Cancer Hospital, Jiangsu Institute of Cancer Research and Nanjing Medical University Affiliated Cancer Hospital, Nanjing 210009, China. 2. Department of Radiology, Jiangsu Cancer Hospital, Jiangsu Institute of Cancer Research and Nanjing Medical University Affiliated Cancer Hospital, Nanjing 210009, China. 3. Department of Radiation Oncology, Jiangsu Cancer Hospital, Jiangsu Institute of Cancer Research and Nanjing Medical University Affiliated Cancer Hospital, Nanjing 210009, China. Electronic address: hexia206@yeah.net.
Abstract
OBJECTIVES: This study aimed to validate the 8th edition of American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) TNM staging system for nasopharyngeal carcinoma (NPC) in non-endemic region. MATERIALS AND METHODS: We recruited 607 patients with histology-proven, previously untreated, non-metastatic NPC treated by intensity-modulated radiotherapy (IMRT) at our center. Harrell's concordance index (c-index) and Akaike information criterion (AIC) were applied to compare the prognostic discrimination between the 7th and 8th edition staging system. RESULTS: For T category, the local recurrence-free survival (LRFS) Kaplan-Meier curves of T1, T2 and T3 were well separated in the 8th edition; however, LRFS did not significantly differ between T3 and T4 (P = 0.166). Moreover, the 7th edition achieved higher c-index (0.702 [95% CI, 0.618-0.787] vs. 0.685 [95% CI, 0.604-0.767]) and lower AIC (766.1 vs. 770.8) than 8th edition for LRFS. With regard to N category, the 8th edition achieved higher c-index (0.796 [95% CI, 0.749-0.843] vs. 0.751 [95% CI, 0.696-0.805]) and lower AIC (1439.4 vs. 1471.9) for distant metastasis-free survival. In terms of overall stage, the 8th edition also had higher c-index (0.798 [95% CI, 0.753-0.844] vs. 0.721 [95% CI, 0.672-0.770]) and lower AIC (1963.9 vs. 2007.2) compared with the 7th edition for overall survival. Furthermore, interval validation by bootstrapping the sample randomly for ~100-1000 times also validated above findings. CONCLUSION: The 8th edition of AJCC/UICC TNM staging system achieved significantly better prognostic discrimination than the 7th edition with regard to N category and overall stage but not T category.
OBJECTIVES: This study aimed to validate the 8th edition of American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) TNM staging system for nasopharyngeal carcinoma (NPC) in non-endemic region. MATERIALS AND METHODS: We recruited 607 patients with histology-proven, previously untreated, non-metastatic NPC treated by intensity-modulated radiotherapy (IMRT) at our center. Harrell's concordance index (c-index) and Akaike information criterion (AIC) were applied to compare the prognostic discrimination between the 7th and 8th edition staging system. RESULTS: For T category, the local recurrence-free survival (LRFS) Kaplan-Meier curves of T1, T2 and T3 were well separated in the 8th edition; however, LRFS did not significantly differ between T3 and T4 (P = 0.166). Moreover, the 7th edition achieved higher c-index (0.702 [95% CI, 0.618-0.787] vs. 0.685 [95% CI, 0.604-0.767]) and lower AIC (766.1 vs. 770.8) than 8th edition for LRFS. With regard to N category, the 8th edition achieved higher c-index (0.796 [95% CI, 0.749-0.843] vs. 0.751 [95% CI, 0.696-0.805]) and lower AIC (1439.4 vs. 1471.9) for distant metastasis-free survival. In terms of overall stage, the 8th edition also had higher c-index (0.798 [95% CI, 0.753-0.844] vs. 0.721 [95% CI, 0.672-0.770]) and lower AIC (1963.9 vs. 2007.2) compared with the 7th edition for overall survival. Furthermore, interval validation by bootstrapping the sample randomly for ~100-1000 times also validated above findings. CONCLUSION: The 8th edition of AJCC/UICC TNM staging system achieved significantly better prognostic discrimination than the 7th edition with regard to N category and overall stage but not T category.