ESTRO 2024 - Abstract Book

S1228

Clinical - Head & neck

ESTRO 2024

Patterns of lymphatic spread in hypopharyngeal and laryngeal squamous cell carcinoma

Esmée L Looman, Roman Ludwig, Lars Widmer, Nil Dülek, Matthias Guckenberger, Panagiotis Balermpas, Jan Unkelbach

University Hospital Zurich, Radiation Oncology, Zurich, Switzerland

Purpose/Objective:

Regional lymph node metastases are common in squamous cell carcinomas (SCC) of the hypopharynx and larynx (1, 2). Yet, detailed reports of lymphatic progression patterns in these carcinomas are rare. With the current guidelines on elective clinical target volume (CTV-N) definition, a large part of the cervical lymph drainage system, which is at risk of harboring occult metastases is irradiated, leading to increased early and late toxicity (1-4). Aiming for further personalization of the CTV-N, this study describes the regional lymphatic spread patterns and risk of lymph node metastases in hypopharyngeal and laryngeal SCC, considering not only T-stage, location and lateralization of the primary tumor, but also involvement of adjacent lymph node levels (LNL) (5, 6).

Material/Methods:

Patients diagnosed with SCC of the hypopharynx or larynx at the University Hospital of Zurich, Zurich, Switzerland, between 2013-2021 were retrospectively analyzed. Baseline patient characteristics and clinicopathological data at time of diagnosis were recorded. Lymph node involvement per level was assessed based on clinical imaging and, if available, pathology. Patterns of lymph node involvement can be visualized through a previously developed web based graphical user interface (www.LyProX.org), which allows querying the number of patients with combinations of co-involved LNLs and tumor characteristics. The dataset will be made publicly available with an upcoming publication.

Results:

A total of 366 patients were included, 119 (33%) patients were diagnosed with hypopharyngeal SCC and 247 (67%) with laryngeal SCC. The most prevalent T-stage at time of diagnosis was T4 (37%) for hypopharynx- and T1 (36%) for larynx-SCC. For hypopharynx-SCC, 73% of patients had regional lymph node metastases, whereas this was 21% for larynx-SCC patients. Ipsilateral lymph node levels II and III were most commonly involved for both hypopharynx- (Level II 59%, Level III 51%) and larynx- (Level II 15%, Level III 15%) SCC. For early T-stage (T1-2) hypopharynx-SCC, the prevalence of lymph node metastases in levels II, III, IV and V was 40%, 40%, 13%, 9% on the ipsilateral side, and 9%, 6%, 2%, 2% on the contralateral side, respectively. For late T stage (T3-4) hypopharynx-SCC, the respective prevalence of LNL involvement was 71%, 58%, 26%, 7% for ipsilateral levels and 31%, 26%, 11%, 3% for contralateral levels. For early T-stage larynx-SCC, involvement of levels II, III, IV and V was found in 4%, 5%, 3%, 1% ipsilateral and 1%, 2%, 1%, 0% contralateral. For late T-stage larynx-SCC, the respective prevalence of LNL involvement was 31%, 28%, 2%, 2% for ipsilateral levels and 11%, 9%, 2%, 4% for contralateral levels.