Prognostic impact of the number of metastatic lymph nodes after surgery in locally advanced hypopharyngeal cancer

BACKGROUND: Postoperative chemoradiotherapy (CRT) is a standard therapy for patients with high-risk factors for head and neck squamous cell carcinoma, including positive margin and extra-nodal extension (ENE). However, the prognostic impact of the number of pathological metastatic lymph nodes (pLNs) in hypopharyngeal carcinoma (HPC) is unclear. Thus, this study aimed to investigate postoperative prognostic factors for locally advanced hypopharyngeal squamous cell carcinoma (LA-HPSCC) with a focus on the number of pLNs. METHODS: We retrospectively analyzed medical records of 99 consecutive patients with LA-HPSCC who underwent total pharyngo-laryngo-esophagectomy (TPLE) and bilateral neck dissection (ND) between December 2002 and May 2019. RESULTS: The median follow-up time for all censored patients was 63.2 months. The median overall survival (OS) was 101.0 months (95% confidence interval [CI] 48.1–134.9). patients had pLNs ≥ 3. Forty-six (45.5%) patients were diagnosed with ENE. Twenty (20.2%) patients received postoperative CRT. The multivariate analysis revealed that pLNs ≥ 3 (median OS: 163.2 vs. 31.8 months, hazard ratio [HR] 2.39, 95% CI 1.16–4.94, p < 0.01) and ENE (median OS: 161.0 vs. 26.3 months, HR 4.60, 95% CI 2.26–9.36, p < 0.01) were significantly associated with poor prognosis and that postoperative CRT (HR 0.34, 95% CI 0.16–0.72, p < 0.01) was significantly associated with better prognosis. The cumulative incidence of distant metastasis was higher in patients with pLNs ≥ 3 than in those with pLNs < 3 (p < 0.01). CONCLUSION: pLNs ≥ 3 and ENE were significant poor prognostic factors for patients with LA-HPSCC who underwent TPLE and bilateral ND.