Outcomes of Early-stage Glottic Carcinoma Treated with Radiation Therapy: A Single Institution Experience.

ABSTRACT

OBJECTIVE:  To evaluate the outcomes of radical intent radiation therapy in early glottic carcinoma (EGC), including local control rate (LCR), disease-free survival (DFS), death specific free survival (DSFS), and overall survival (OS) rates, in Saudi patients treated at a single institution.  Materials and methods: This is an institutional review board (IRB) approved, retrospective study of 27 patients with T1-2 N0 M0, early glottic carcinoma (EGC) who were treated from 2010 to 2015 at our institution with different radiotherapy (RT) fractionation regimens. The regimens included six different fractionation schedules of radiotherapy (RT) 50 Gy (20 x 2.5 Gy) dose prescribed to 95% isodose line, 52.4 Gy (20 x 2.52 Gy), 63 Gy (28 x 2.25 Gy), 66 Gy (33 x 2 Gy), and 70 Gy (35 x 2 Gy). The cohort was stratified into two groups, ≤ 52.5 Gy (n=15) and > 52.5 Gy (n=12). The median follow-up of all patients was 31.7 months (range 7-82). RESULTS: The mean age of the cohort was 64.5 years (median 65, range 41-83). Eleven patients (40.7%) had a history of smoking. The majority of the cohort was with T1a EGC (70.4%, n=19), and anterior commissure invasion was seen in three patients (11.1%). The mean RT doses were 55.6 Gy (range 50-70). The five-year LCR, DFS, DSFS, and OS rates were 83.1%, 80.0%, 96.2%, and 92.6%, respectively. The LCR rates for those receiving a dose of 52.5 Gy or less were 61.3 months compared to 89.5 months for those who received more than 52.5 Gy (p=0.994). Non-smokers and patients with an unknown smoking history achieved a five-year LCR of 100%, while patients with a positive smoking history achieved a five-year LCR of 60.6% (p=0.044). CONCLUSION:  Radiation therapy for EGC in our patients showed reasonable five-year LCR with larynx preservation at 83.1%, DFS 80.0%, five-year OS rate 92.6%, and DSFS rate 96.2%. We found that smoking had a significant correlation with LCR. However, large prospective trials are warranted to evaluate the efficacy of overall treatment time, dose per fraction of above 2 Gy, and smoking effect.