Selection and validation of intensity-modulated radiotherapy (IMRT) alone beneficiaries among elderly patients with stage T1-2N1M0 nasopharyngeal carcinoma and ACE-27 scores < 2: a multi-center study

Background Elderly patients are underrepresented in clinical trials supporting concurrent chemoradiotherapy (CCRT) as the standard treatment for patients with stage T1-2N1M0 nasopharyngeal carcinoma (NPC). This study aimed to develop and validate a prognostic nomogram in elderly patients (≥ 60 years) with stage T1-2N1M0 NPC to distinguish low-risk subgroup for whom intensity-modulated radiotherapy (IMRT) alone is sufficient. Methods This multi-center study retrospectively analyzed 615 elderly patients with stage T1-2N1M0 NPC and Adult Comorbidity Evaluation-27 (ACE-27) scores < 2, including 297 and 318 patients in the training and validation cohorts, respectively. A nomogram for cancer-specific survival (CSS) was developed using multivariable Cox regression and validated using concordance indices (C-index), calibration curves, and decision curve analysis (DCA). Survival outcomes were compared using log-rank tests. Results Four independent predictors for CSS were identified to construct the nomograms: age, Epstein-Barr virus DNA (EBV-DNA), and extracapsular spread (ECS) of retropharyngeal and cervical lymph nodes. Nomogram A incorporated all four predictors. Nomograms B, C, and D were constructed based on T stage, EBV-DNA, and their combination, respectively. In the training cohort, the C-index of Nomogram A was 0.768, which was statistically higher than those of Nomogram B (0.530), Nomogram C (0.635), and Nomogram D (0.641). Calibration curves and DCA demonstrated good calibration and clinical utility for Nomogram A. Risk stratification using Nomogram A showed that in the low-risk group, IMRT alone achieved comparable 5-year CSS to chemoradiotherapy (CRT). These findings were confirmed in the validation cohort. Conclusions A nomogram integrating lymph node ECS, age, and EBV-DNA was developed to effectively identify optimal candidates among elderly patients with stage T1-2N1M0 NPC and ACE-27 scores < 2 for treatment with IMRT alone. Clinical trial number Not applicable.