Nodal fusion and soft tissue invasion provide incremental risk stratification in pathologically N3b classification hypopharyngeal squamous cell carcinoma.

BACKGROUND: Hypopharyngeal squamous cell carcinoma (HPSCC) patients with extranodal extension (ENE) are classified as pN3b and have the poorest prognosis. However, further risk stratification within this high-risk subgroup remains controversial. METHODS: We retrospectively reviewed 141 HPSCC patients who underwent neck dissection and whose disease was confirmed as pN3b at our hospital between January 2012 and December 2021. The primary endpoint was disease-free survival (DFS). Survival analysis was performed using the Kaplan‒Meier method with the log-rank test for group comparisons. Multivariable analysis was conducted using Cox proportional hazards regression. RESULTS: Compared with patients without lymph node fusion (LNF, n = 30), those with LNF (n = 111) had significantly worse overall survival (OS, P = 0.0177), DFS (P = 0.0302), and distant metastasis-free survival (DMFS, P = 0.0404). Notably, patients with both LNF and soft tissue invasion (STI, n = 17) exhibited the poorest outcomes, with a median OS of only 19 months (95% CI: 4.210-33.790). Compared with patients with LNF alone (n = 94), those with both LNF and STI had significantly shorter OS (P = 0.0385), DFS (P = 0.0032), and regional recurrence-free survival (RFS, P = 0.0143). Multivariable analysis revealed that LNF and pT classification were independent risk factors for the entire pN3b cohort, whereas STI and pT classification were independent risk factors specifically for the LNF-positive subgroup. CONCLUSION: We identified two candidate prognostic features (LNF and STI) for pN3b HPSCC patients. These findings may assist clinicians in identifying high-risk patients and guiding more personalized treatment decisions.