A novel surgical T staging system for recurrent nasopharyngeal carcinoma: advancing prognostic accuracy and clinical applicability

OBJECTIVE: The aim of this study was to develop and validate a novel surgical T (sT) staging system for recurrent nasopharyngeal carcinoma (rNPC) that better reflects anatomical barriers to resection and improves prognostic accuracy compared with the American Joint Committee on Cancer (AJCC) staging system. METHODS: Cadaveric dissections and a retrospective analysis of 211 patients with rNPC undergoing endoscopic nasopharyngectomy were conducted. RESULTS: The proposed sT staging system incorporates 3 key anatomical barriers-the pharyngobasilar fascia (PBF), interpterygoid fascia (IPF), and dura mater-to stratify rNPC into 4 stages (sT1-sT4). In a retrospective cohort of 211 patients who underwent endoscopic nasopharyngectomy, the 5-year overall survival (OS) rates based on AJCC rT staging were 92.9% (rT1), 72.9% (rT2), 69.3% (rT3), and 37.1% (rT4). In contrast, the 5-year OS rates under the sT staging system were 93.4% (sT1), 80.3% (sT2), 60.0% (sT3), and 34.0% (sT4), demonstrating improved separation of survival outcomes across stages (p < 0.001). In the held-out validation cohort under a hash-locked 80/20 split, the sT model achieved superior discrimination compared with AJCC rT (C-index, 0.624 vs 0.546; 2-year time area under the curve [AUC] 0.709 [simple/IPCW 0.709/0.740] vs 0.632 [0.632/0.667]) with acceptable calibration at 2-4 years. The 5-year AUC was not estimable because no patients remained event free beyond 5 years. CONCLUSIONS: By encoding barrier-guided spread aligned with endoscopic resectability (PBF, IPF, and dura), the sT system improves external discrimination and stage separation, thereby enhancing preoperative risk stratification and surgical planning. External, multi-institutional validation with longer follow-up is warranted.