Lymphnode metastasis patterns in primary sites of hypopharyngeal cancer: A retrospective analysis from multicenter data.

Abstract

e18559 Background: Understanding the pattern of lymph node metastasis (LNM) in hypopharyngeal cancers (HPC) could help both surgeons and radiologists make decisions in the management of cervical lymph node. Our objective is to identify the pattern of nodal spread and the relationship between features of primary tumor and LNM in HPC. Methods: 244 newly diagnosed HPC patients during 2014 to 2017 were recruited from 3 specialized cancer hospitals in mainland China. All patients underwent head and neck magnetic resonance imaging(MRI) and received definitive radiotherapy ± concurrent chemotherapy. The features of primary tumor (tumor size, primary location, and extent of invasion) and the involvement of lymph nodes in each level were reassessed. According to the incidence of LNM, these levels were sequenced and sorted into drainage stations. Meanwhile, univariate and multivariate analysis was used to determine the risk factors for bilateral and regional lymph node metastasis. Results: The cohort consisted 195 piriform sinus cancers (PSC), 47 posterior wall cancers (PWC), 2 Post-cricoid cancers (PCC). 176 patients (72.1%) presented with MRI-detectable LNM. The overall LNM rates for level II-VI and retropharyngeal lymph nodes (RPLNs) were 59.0%, 52.9%, 14.3%, 1.6%, 2.9% and 14.7% respectively. Based on the prevalence of LNM in each level, we suppose that the lymphatic drainage of PSC was carried out in sequence along three stations: Level II & III (61.0% & 55.4%), Level IV & RPLN (15.9% & 10.3%), and Level V & VI(1.5% & 3.1%). While, for PWC the lymphatic drainage is carried out along two stations: Level II, III & RPLN (48.9%,40.4% & 34.0%), and Level IV-VI (6.4%, 0% and 2.1%). According to univariate analysis, primary subsite, posterior wall, post-cricoid and non-pyriform sinus invasion were correlated with bilateral LNM. The presence of RPLNs was correlated with larger tumor size(>4cm), primary subsite, posterior wall and non-pyriform sinus invasion. In further multivariate analysis, posterior wall invasion was significantly correlated with bilateral LNM (P = 0.030, HR = 2.853 95%CI, 1.110-7.338). Tumor size > 4cm(P = 0.017, HR = 2.545, 95%CI,1.180-5.488) and posterior wall invasion(P = 0.017, HR = 2.880 95%CI, 1.209-6.862) were correlated with RPLN metastasis. Conclusions: Different primary sites of HPC have different lymphnode metastasis patterns. Piriform sinus cancer tends to metastasize to the ipsilateral Level II&III. Posterior wall cancer tends to metastasize bilaterally to Level II, III and RPLN.