Pretreatment nodal SUVmax predicts neck progression in hypopharyngeal cancer undergoing definitive chemoradiotherapy, while higher radiotherapy dose improves regional control particularly in the high SUV-N subgroup: a long-term outcome study

F-FDG PET/CT was utilized to calculate the SUV-T and SUV-N, with clinical correlations assessed via Gamma statistic and survival outcomes analyzed using Kaplan-Meier methods and multivariable Cox regression. The results were further strengthened using multivariable Fine-Gray competing risk regression analysis, considering death as a competing risk when appropriate. After a median follow-up of 9.0 years (95% CI: 7.7-10.2), SUV-N correlated significantly with N category (Gamma coefficient = 0.63, P < 0.001), AJCC stage (Gamma coefficient = 0.53, P = 0.005), and radiologic extranodal extension (Gamma coefficient = 0.80, P < 0.001). SUV-N ≥ 13 predicted worse 5-year regional control (51.8% vs 86.1%, P < 0.001) and showed a borderline significant association with overall survival (26.3% vs 42.6%, P = 0.074). Multivariable analysis confirmed SUV-N ≥ 13 as an independent predictor of regional progression (HR = 4.59, P < 0.001). Competing risk analysis further confirmed that SUV-N ≥ 13 remained a robust predictor of regional progression (subdistribution hazard ratio [SHR] = 4.65; 95% CI: 2.23-9.69; P < 0.001), even after accounting for death as a competing risk. Conversely, radiotherapy dose escalation to 72-74 Gy (EQD2) significantly reduced the risk of regional progression (multivariable Cox regression: HR = 0.41, P = 0.047; multivariable competing risk regression: SHR = 0.37; 95% CI: 0.17-0.84; P = 0.017). Exploratory subgroup analysis revealed that this therapeutic benefit was primarily driven by the high SUV-N subgroup (SUV-N ≥ 13), where dose escalation significantly reduced regional progression (Fine-Gray P = 0.018), whereas no such benefit was observed in the low SUV-N subgroup (Fine-Gray P = 0.740). In contrast, SUV-T was not prognostic for survival outcomes. In conclusion, high pretreatment SUV-N is an independent prognostic factor for regional progression in node-positive HPSCC undergoing definitive chemoradiotherapy. Integrating SUV-N into treatment planning may guide intensified therapies for high-risk patients.