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

Abstract

PurposeTo confirm safety and feasibility of hypofractionated SBRT for early-stage glottic laryngeal cancer.MethodsTwenty 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).ResultsMedian 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.ConclusionsWe 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 registrationClinicalTrials.gov NCT01984502

A Review of Controversial Issues in the Management of Head and Neck Cancer: A Swiss Multidisciplinary and Multi-Institutional Patterns of Care Study—Part 2 (Radiation Oncology)

“…When compared with a historical control group, which was treated to the whole larynx (66 Gy in 33 fractions), single vocal cord irradiation yielded less grade ≥2 acute toxicity (17 vs. 66%, p < 0.01) and lower voice handicap index scores in almost all follow-up visits performed in regular short intervals until 18th month ( p < 0.01). In contrast, a recently published phase I trial with extremely hypofractionated radiotherapy using robotic SBRT yielded inferior local control and not necessarily less toxicity compared to the literature (51). This was possibly because of the irregular laryngeal motions occurring during a protracted dose delivery and the lack of the current robotic SBRT unit's capability to handle them.…”

Early Closure of a Phase 1 Clinical Trial for SABR in Early-Stage Glottic Cancer

“…23 Similar to prior reports, we observed that only patients who continued to smoke had serious adverse events. 24,25 The high number of active smokers (3 of 6) in the second arm and only 1 (of 7) in the first arm may be a limitation of our study in evaluating the impact of fraction size on late toxicity. However, considering that severe toxicity was rare (<2%) when the proportion of current smokers was high (50%-90%) in previous studies of conventional fractionated radiation therapy, fraction size might be an additional risk factor for severe toxicity independent of smoking habit, 8,23 The voice outcomes assessed by EGG were not significantly different between the 2 arms.…”

“…However, recent data from Schwartz et al revealed severe late toxicity during SABR for early-stage glottic cancer, in which grade 4 laryngeal edema occurred in 1 of 13 patients treated with 45 Gy in 10 fractions. 25 Moreover, Ling et al suggested that salvage SABR was safe and effective for recurrent head and neck cancer, except for patients with cancer of the larynx/hypopharynx, who experienced significantly greater late toxicity. 28…”

Efficacy of laryngectomy alone for treatment of locally advanced laryngeal cancer: A stage‐ and subsite‐specific survival analysis

“…Larynx cancer has been shown to be an independent risk factor for long‐term dysphagia among patients treated with radiation therapy for head and neck cancer . There are currently studies looking at dose modulation and hypofractionation to reduce this disabling side effect of therapy …”