Outcomes Of Carotid Sparing Radiotherapy For Early Stage Glottic Cancer: Turkish Society For Radiation Oncology Group (TROD) Retrospective Study

Abstract

To report clinical outcomes after on carotid-sparing intensity modulated radiotherapy for early stage laryngeal cancer. We retrospectively analyzed disease, and treatment characteristics for 201 patients with early-stage glottic laryngeal cancer treated in 6 TROD centers between 2012-2019. Using AJCC 8th., TNM staging system, 28 (14%) patients were classified as Tis, 153 (76%) as T1 and 20 (10%) as T2. Dosimetric parameters and local-regional control results of patients treated with carotid sparing IMRT / VMAT (Intensity-modulated radiation therapy / volumetric modulated arc therapy) techniques were evaluated. Median follow-up time was 31 (6-88) months. Median age was 64 (range 39-87) and 188 (93.5%) of the cases were male and 13 (6.5%) female. Anterior commissure involvement was detected in 47 (23.4%) cases. A total of 174 (87%) cases were treated with VMAT and 27 (13%) with IMRT. Total dose ranged from 63 to 70 Gy (median 66Gy) in 28 to 35 fractions using 2 to 2.25 Gy (Median: 2.25 Gy) daily fractions. Local recurrence was detected in six patients (3%), regional recurrence in 3 patients (1.5%), and local and regional recurrence in 1 patient (0.5%). The actuarial 1- and 3-year local control rates were 99.4% and 94.7%, respectively. The actuarial 1 and 3 year local-regional control rates were 98.4% and 93%. Five of seven local recurrences were observed in patients treated with hypofractionation. Stage, anterior commissure involvement, IMRT technique and type of fractionation were not found to be prognostic factor on local control. Nine patients experienced Grade 3-4 acute laryngeal edema (Gr 3; 8 patients, Gr 4; 1 patient), and 3 patients experienced grade 3-4 late laryngeal edema (Gr 3; 2 patients, Gr 4; 1 patients). The second primary cancer was seen in 18 (9%) cases. No transient ischemic attack or stroke was observed. Oncologic outcomes of patients treated with carotid sparing IMRT were excellent with acceptable side effect. Long-term follow-up is needed to demonstrate outcomes for long-term toxicity.