Single vocal cord irradiation (SVCI): image-guided intensity-modulated hypofractionated radiotherapy for T1a glottic cancer: early clinical results
Menée à partir de données portant sur 30 patients atteints cancer de la glotte de stade T1 (durée médiane de suivi : 30 mois), cette étude évalue l'efficacité, du point de vue du taux de contrôle local à 2 ans, et la faisabilité de l'irradiation d'une seule corde vocale par radiothérapie hypofractionnée avec modulation d'intensité et guidage à l'aide de l'imagerie
Résumé en anglais
Purpose/objectives : This retrospective analysis of prospectively collected data reports on feasibility, outcome, toxicity, and voice-handicap index (VHI) of patients with T1a glottic cancer treated by a novel IMRT technique developed at our institution to treat only the involved vocal cord; the single vocal cord irradiation (SVCI).
Methods and Materials : Thirty patients with T1a glottic cancer were treated by means of SVCI. Dose prescription was set to 16*3.63 Gy (TD 58.08 Gy). The clinical target volume (CTV) was the entire vocal cord. Set-up verification was done by means of an online correction protocol using cone-beam CT. Data for voice quality assessment were collected prospectively at baseline, end of treatment, 4,6, and 12 weeks and 6, 12, and 18 months after treatment using VHI questionnaires.
Results : After a median follow-up of 30 months (range, 7-50), the 2-year local control and overall survival rates were 100% and 90% since no single local recurrence was reported and three patients died because of comorbidity. All patients have completed the intended treatment schedule; no treatment interruptions and no grade 3 acute toxicity were reported. Grade 2 acute dermatitis or dysphagia was reported in only 5 patients (17%). No serious late toxicity was reported; only one patient developed temporary grade 2 laryngeal oedema, and responded to short-course of corticosteroid. VHI improved significantly from 33.5 at baseline to 9.5 and 10 at 6-weeks and 18-months, respectively (p<0.001). The control group, treated to the whole larynx, had comparable LC-rates (92.2% vs. 100%,p=0.24), but more acute toxicity (66% vs. 17%,p<0.0001) and higher VHI-scores (23.8 and 16.7 10 at 6- and 18-mothns, respectively, p<0.001).
Conclusion : SVCI is feasible and resulted in maximal local control rate at 2 years. The deterioration in VHI-scores was slight and temporary and subsequently improved to normal level. Long-term follow-up is needed to consolidate these promising results.
