Date of Award

January 2024

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Saral Mehra

Abstract

Stage T3 laryngeal cancer is defined by the presence of vocal cord fixation and/or invasion into any of the following: pre-epiglottic space, paraglottic fat, post-cricoid space, or inner cortex of the thyroid cartilage. These cancers are usually treated with chemoradiation rather than upfront total laryngectomy. To our knowledge, no studies have directly compared differences in survival among the varied features within the T3 staging category. This study aims to determine how the presence of each of these staging features impacts overall and laryngectomy-free survival.Patients with clinically-diagnosed T3 laryngeal squamous cell carcinoma seen at our institution between 2010-2021 were retrospectively identified. Medical record information was collected for patient demographics, tumor characteristics, treatment course, and survival. Records were reviewed with head and neck surgeons and neuroradiologists when there was uncertainty. Patients were excluded if tumor and/or treatment information was incomplete, if metastatic disease was present at diagnosis, or if they were treated with upfront laryngectomy. For statistical analysis, the cohort was stratified in two ways: by number of T3 staging features and by type of feature. Pre-epiglottic, paraglottic, and post-cricoid space invasion were grouped together as “soft tissue invasion”. The primary outcome was overall survival (OS), and the secondary outcome was laryngectomy-free survival (LFS, the proportion of patients alive without laryngectomy, out of all alive patients at a certain timepoint). 102 patients met inclusion criteria for analysis, who were 79.4% male (81) and were diagnosed at a mean age of 65.3 ± 11.4 years. 68.4% of patients (67) presented with a single T3 staging feature. 48.0% of patients (49) had vocal cord fixation (either alone or in combination with other features), 63.7% (65) had soft tissue invasion, and 10.8% (11) had thyroid cartilage involvement. OS was 68.6% at 2 years and 47.9% at 5 years. LFS was 74.2% at 2 years and 72.1% at 5 years. On Kaplan-Meier survival analysis comparing different staging features, thyroid cartilage involvement had a significant impact on OS (p<0.001). Cox proportional hazard regression analysis showed that older age at diagnosis (p<0.001), higher overall cancer stage (p=0.003), and thyroid cartilage involvement (p<0.001) all had significant impacts on OS. There were no demographic or clinical features which had a significant impact on LFS, i.e. features of patients who were more likely to receive salvage laryngectomy. Our results suggest that overall survival may be worse for patients with thyroid cartilage invasion. The difficulty of radiologically determining the degree of thyroid cartilage invasion, which distinguishes stage T3 from stage T4 laryngeal cancer, may contribute to this finding. However, the possibility that any thyroid cartilage invasion portends worse survival cannot be excluded. In order to optimize survival for patients with T3 laryngeal cancer, our findings should be further validated with larger datasets and prospective studies to assess the need for potential changes in tumor staging or treatment guidelines.

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This is an Open Access Thesis.

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