SBRT for early-stage glottic larynx cancer-Initial clinical outcomes from a phase I clinical trial

Abstract

Purpose: To confirm safety and feasibility of hypofractionated SBRT for early-stage glottic laryngeal cancer.

Methods: Twenty consecutive patients with cTis-T2N0M0 carcinoma of glottic larynx were enrolled. Patients entered dose-fractionation cohorts of incrementally shorter bio-equivalent schedules starting with 50 Gy in 15 fractions (fx), followed by 45 Gy/10 fx and, finally, 42.5 Gy/5 fx. Maximum combined CTV-PTV expansion was limited to 5 mm. Patients were treated on a Model G5 Cyberknife (Accuray, Sunnyvale, CA).

Results: Median follow-up is 13.4 months (range: 5.6-24.6 months), with 12 patients followed for at least one year. Maximum acute toxicity consisted of grade 2 hoarseness and dysphagia. Maximum chronic toxicity was seen in one patient treated with 45 Gy/10 fx who continued to smoke >1 pack/day and ultimately required protective tracheostomy. At 1-year follow-up, estimated local disease free survival for the full cohort was 82%. Overall survival is 100% at last follow-up.

Conclusions: We were able to reduce equipotent total fractions of SBRT from 15 to 5 without exceeding protocol-defined acute/subacute toxicity limits. With limited follow-up, disease control appears comparable to standard treatment. We continue to enroll to the 42.5 Gy/5 fx cohort and follow patients for late toxicity.

Trial registration: ClinicalTrials.gov NCT01984502.

Conflict of interest statement

Competing Interests: Robert Timmerman, MD, FACR received research funding unrelated to this manuscript from Accuray, Inc. (Sunnyvale, CA), which manufactures Cyberknife.

Figures

Fig 1. CONSORT diagram.

Fig 2. Estimated local recurrence free survival by fractionation cohort.

Fig 3. Estimated local recurrence free survival for cT1 and cT2 lesions.