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Thesis Format



Master of Science


Epidemiology and Biostatistics


Dr. Amit Garg

2nd Supervisor

Dr. Amardeep Thind


Background: Subglottic squamous cell carcinoma is a rare subsite of laryngeal cancer, which is believed to behave more aggressively and portend a worse prognosis than other laryngeal cancer subsites (supraglottis and glottis). Our objective was to utilize a population-based cancer registry to report the overall survival and laryngectomy-free survival in patients diagnosed with subglottic squamous cell carcinoma, and to examine trends in outcomes over time. We also compared overall survival in patients treated with primary laryngectomy versus radiation.

Methods: We carried out a retrospective population-based study of patients with a new diagnosis of squamous cell carcinoma in the province of Ontario, Canada over a 15-year period (1995-2009). We identified patients with a new diagnosis of subglottic squamous cell carcinoma using the Ontario Cancer Registry. We determined demographics, comorbidity measures, staging, survival and primary treatment with laryngectomy using the linked population-based healthcare databases in Ontario. We first determined the overall survival and laryngectomy free survival of patients with subglottic cancer. In a secular trends study, we then examined the trends in overall survival and laryngectomy-free survival over the study period.

Results: A total of 4927 cases of laryngeal carcinoma were identified, with 89 patients defined as primary subglottic carcinoma (1.8%). Among the subglottic cohort, 68 (76.4%) were male, and the mean (25th, 75th percentile) age at diagnosis was 68 (60- 77 years). The 5-year overall survival was 47.2%, while the 5-year laryngectomy-free survival was 31.5%. No differences were observed in overall survival (OS) or laryngectomy-free survival (LFS) across years over the 15-year study period (p=0.42 OS, p=0.83 LFS). Thirteen patients (15%) were treated with primary laryngectomy. Primary treatment with laryngectomy was not associated with a different risk of mortality compared with radiation.

Conclusions: The overall survival and laryngectomy-free survival of patients with subglottic carcinoma is poor and has remained stable over time (1995-2009). Primary treatment with laryngectomy does not appear to improve overall survival compared with primary radiation.

Summary for Lay Audience

Cancer that occurs below the level of the vocal cords, also known as subglottic cancer, is very rare. Subglottic cancer is thought to lead to a higher chance of death than cancer that occurs in the vocal cords or above the vocal cords, but we don’t know for sure because it is so rare. Our goal with this study was to use a large database of patients with subglottic cancer to determine if it does have a higher chance of death than other vocal cord cancers and whether treatment with surgery or radiation is better. We looked at all patients in Ontario from 1995-2009 who were diagnosed with subglottic cancer. We searched the database for other factors that might contribute to the survival of patients with subglottic caner and impact their chance of cure. We used the data to determine how many patients were still alive at 5 years after a diagnosis of subglottic cancer and how many patients were still alive at 5 years and still retained their voice box (that is, they did not have to have it removed to cure the cancer).

In total we found 89 patients who had subglottic cancer in Ontario during our study period. At 5 years, 47.2% of patients were still alive and 31.5% of patients will still alive and still had their voice box. Over the 15 years of our study, we did not find that the chance of survival from subglottic cancer changed. Fifteen percent of patients were treated with surgery and the rest were treated with radiation. We found that the treatment chosen did not impact survival from subglottic cancer.

Patients with subglottic cancer have a lower chance of survival than patients with cancer in the vocal cords or above the vocal cords, and survival has not changed over the study timeframe 1995-2009. The treatment chosen for subglottic cancer does not appear to impact survival at 5 years. More research is needed to improve the overall survival for patients with subglottic cancer and to determine the best treatment options.

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License