Lower-neck involvement and post–concurrent chemoradiotherapy response predict distant metastasis in head and neck cancer

Purpose: This study aimed to evaluate whether lower-neck involvement and post-concurrent chemoradiotherapy (CCRT) response predict distant metastasis (DM) in patients with head and neck squamous cell carcinoma (HNSCC) treated with definitive intensity-modulated radiotherapy (IMRT)-based CCRT.Materials and Methods: We retrospectively analyzed 210 patients with non-metastatic HNSCC treated with definitive IMRT-based CCRT between 2009 and 2020.Lower-neck involvement was defined as radiologic involvement of inferior cervical lymph nodes.Post-treatment response was categorized as complete response (CR) versus non-CR.Logistic and Cox regression models were used to identify predictors of DM and survival outcomes.Results: At a median follow-up of 59.8 months, DM developed in 51 patients (24.3%).In multivariable logistic analysis, lower-neck involvement (odds ratio [OR], 2.32; 95% confidence interval [CI], 1.18 to 4.54; p = 0.014) and non-CR (OR, 2.57; 95% CI, 1.31 to 5.05; p = 0.006) independently predicted DM.In Cox analyses, lower-neck involvement was associated with inferior distant metastasis-free survival (DMFS) (hazard ratio [HR], 2.07; 95% CI, 1.15 to 3.75; p = 0.016) and progression-free survival (PFS) (HR, 1.93; 95% CI, 1.19 to 3.14; p = 0.008), whereas non-CR predicted worse DMFS (HR, 2.71; 95% CI, 1.49 to 4.95; p = 0.001), PFS (HR, 3.77; 95% CI, 2.25 to 6.33; p < 0.001), and overall survival (HR, 5.08; 95% CI, 1.94 to 13.34; p < 0.001).Conclusion: Lower-neck involvement and post-CCRT response independently predict DM after definitive CCRT for HNSCC and may improve risk stratification for systemic failure.