Akademik Veri Yönetim Sistemi
iARTIST-International Advanced Radiotherapy Techniques Symposium, İstanbul, Türkiye, 12 - 13 Haziran 2026, ss.1, (Özet Bildiri)
Background: The AJCC 9th edition TNM staging system for nasopharyngeal carcinoma (NPC) introduced major revisions, including advanced extranodal extension for N3 classification, subdivision of metastatic disease, and restriction of stage IV to metastatic disease only. Although validated primarily in endemic cohorts, its applicability in non-endemic settings remains unclear. We compared the prognostic performance of TNM-8 and TNM-9 in a non-endemic NPC cohort.
Materials-Methods: This study included 112 patients with histologically confirmed NPC treated at our center between January 2010 and January 2025. Median age was 50 years (range, 12–76), and 77% were male. Nodal involvement was present in 91%, and distant metastases in 6.3%. All patients were restaged according to both TNM-8 and TNM-9 criteria. Radiotherapy was delivered via VMAT (80.5%) or 3D-CRT (19.5%), with concurrent platinum-based chemotherapy administered in 86.7%. Overall survival (OS) and progression-free survival (PFS) were evaluated using Kaplan-Meier analysis with log-rank testing, univariable (UVA) and multivariable (MVA) analyses, Firth penalized regression for sparse events, and Harrell’s C-index with bootstrap resampling.
Results: After a median follow-up of 63.7 months, 20 patients (17.9%) had died, and 26 (23.2%) had experienced disease progression. In Kaplan-Meier analysis, TNM-9 showed statistically significant separation between stage groups for both OS (p=0.024) and PFS (p=0.005), whereas TNM-8 did not reach significance for either endpoint (OS p=0.168; PFS p=0.053). In UVA for PFS, TNM-9 demonstrated stronger prognostic value than TNM-8 (HR=1.96, 95% CI 1.18–3.25, p=0.009 vs HR=1.80, 95% CI 1.02–3.16, p=0.041). Harrell's C-index favored TNM-9 for both OS (0.658 vs 0.599) and PFS (0.681 vs 0.661). Firth penalized regression further supported TNM-9, showing better model fit for both OS (p=0.044 vs 0.169) and PFS (p=0.011 vs 0.056). In MVA for sex, gross tumor volume (GTV), age (>=50 years), and TNM-9 retained independent prognostic significance for PFS (HR=1.70, 95% CI 1.02–2.83, p=0.041), while TNM-8 did not (HR=1.35, 95% CI 0.76–2.39, p=0.300). GTV (HR=1.010 per mL, p=0.001) and age >=50 years (HR=4.08, p=0.005) were the strongest independent predictors. The revised stage groupings led to substantial redistribution: the proportion classified as stage IV dropped from 49.1% under TNM-8 to 6.2% under TNM-9, as 87% of former stage IVA patients were reclassified to stage III.
Conclusions: The AJCC 9th edition staging system demonstrated superior prognostic stratification compared with the 8th edition in NPC patients from a non-endemic region. Notably, TNM-9 retained independent prognostic significance for PFS in multivariable analysis, whereas TNM-8 did not. These findings support the adoption of TNM-9 for prognostic stratification in non-endemic settings, although larger multicenter validation studies are warranted.
Keywords: nasopharyngeal carcinoma, TNM staging, validation