title: Comparison of survival between radiation therapy and trans-oral laser microsurgery for early glottic cancer patients; a retrospective cohort study.
abstract: BACKGROUND
  The literature reports various treatment methodologies, such as trans-oral laser microsurgery, radiation therapy, total/partial laryngectomies, and concurrent radiation chemotherapy for patients with early larynx cancer. However, at the forefront of early glottis treatment is trans-oral laser microsurgery and radiation therapy, likely due to better functional and survival outcomes. Here we conduct the largest Canadian head-to-head comparison of consecutive patients treated with either radiation therapy or trans-oral laser microsurgery. Additionally, we compare these two treatments and their 5-year survival rates post treatment to add to the existing literature.
  
  
  METHODS
  Charts of patients who were diagnosed with early glottic cancer between 2006 and 2013 were reviewed. Seventy-five patients were identified, and split into 2 groups based on their primary treatment, trans-oral laser microsurgery and radiation therapy. Kaplan-Meier survival curves, life-tables, and the log-rank statistic were reported to determine if there was a difference between the two treatment groups and their disease-specific survival, disease-free survival, and total laryngectomy-free survival. Additionally, each different survival analysis was stratified by potential confounding variables, to help conclude which treatment is more efficacious in this population.
  
  
  RESULTS
  The 5-year disease-specific survival rate is 93.3 % σ = 0.063 and 90.8 % σ = 0.056 for patients treated with trans-oral laser microsurgery and radiation therapy, respectively (χ (2) < 0.001, p = 0.983). The disease free survival rate is 60.0 % (σ =0.121) for patients treated with trans-oral laser microsurgery, and 67.2 % (σ = 0.074) for those who received RT (χ (2) = 0.19, p = 0.663). Additionally, the total laryngectomy-free survival rate is 84.1 % (σ = 0.1) and 79.1 % (σ = 0.072) for patients' early glottic cancer treated by trans-oral laser microsurgery and radiation therapy, respectively (χ (2) = 0.235, p = 0.628). Chi-square analysis of age-group versus treatment group (χ (2) = 6.455, p = 0.04) and T-stage versus treatment group (χ (2) = 11.3, p = 0.001) revealed a statistically significant relationship, suggesting survival analysis should be stratified by these variables. However, after stratification, there was no statistically significant difference between the trans-oral laser microsurgery and radiation therapy groups in any of the survival analyses.
  
  
  CONCLUSIONS
  No difference was demonstrated in the 5-year disease-specific survival, disease-free survival, and total laryngectomy-free survival, between the RT and TLM treatment groups. Additionally, both groups showed similar 5-year survival after stratifying by confounding variables.
authors.affiliation: Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Suite M1 102, Toronto, ON, M4N 3 M5, Canada.
authors.forename: R J
authors.initials: RJ
authors.lastname: De Santis
authors.affiliation: Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, ON, M4N 3 M5, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Poon
authors.affiliation: Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, ON, M4N 3 M5, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, ON, M4N 3 M5, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Karam
authors.affiliation: Department of Otolaryngology - Head & Neck Surgery, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Suite M1 102, Toronto, ON, M4N 3 M5, Canada.
authors.forename: D J
authors.initials: DJ
authors.lastname: Enepekides
authors.affiliation: Department of Otolaryngology - Head & Neck Surgery, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Suite M1 102, Toronto, ON, M4N 3 M5, Canada. kevin.higgins@sunnybrook.ca.
authors.forename: K M
authors.initials: KM
authors.lastname: Higgins
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005931:Glottis / Q000601:surgery*; D006801:Humans; D007822:Laryngeal Neoplasms / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery*; D007825:Laryngectomy; D053685:Laser Therapy / Q000379:methods*; D008297:Male; D008866:Microsurgery / Q000379:methods*; D008875:Middle Aged; D012189:Retrospective Studies; D016019:Survival Analysis; D015996:Survival Rate
keywords: 5-year survival; Early glottic cancer; Radiation therapy; T1; T2; Trans-oral laser microsurgery