Has that been studied? The traditional glottic fields include some of the lymphatics and larynx treatment as a whole always includes the bilateral neck, unlike say, early stage tonsil.
Int J Radiat Oncol Biol Phys. 2015 Jun 14. pii: S0360-3016(15)00637-9. doi: 10.1016/j.ijrobp.2015.06.016. [Epub ahead of print]
Single Vocal Cord Irradiation: Image Guided Intensity Modulated HypofractionatedRadiation Therapy for T1a Glottic Cancer: Early Clinical Results.
Al-Mamgani A1,
Kwa SL2,
Tans L2,
Moring M2,
Fransen D2,
Mehilal R2,
Verduijn GM2,
Baatenburg de Jong RJ3,
Heijmen BJ2,
Levendag PC2.
Author information
Abstract
PURPOSE:
To report, from a retrospective analysis of prospectively collected data, on the feasibility, outcome, toxicity, and voice-handicap index (VHI) of patients with T1a glottic cancer treated by a novel intensity modulated radiation therapy technique developed at our institution to treat only the involved vocal cord: 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 (total dose 58.08 Gy). The clinical target volume was the entire vocal cord. Setup verification was done by means of an online correction protocol using cone beam computed tomography. Data for voice quality assessment were collected prospectively at baseline, end of treatment, and 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 months), the 2-year local control and overall survival rates were 100% and 90% because no single local recurrence was reported and 3 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 1 patient developed temporary grade 2 laryngeal edema, and responded to a short-course of corticosteroid. The VHI improved significantly, from 33.5 at baseline to 9.5 and 10 at 6 weeks and 18 months, respectively (P<.001). The control group, treated to the whole larynx, had comparable local control rates (92.2% vs 100%, P=.24) but more acute toxicity (66% vs 17%, P<.0001) and higher VHI scores (23.8 and 16.7 at 6 weeks and 18 months, respectively, P<.0001).
CONCLUSION:
Single vocal cord irradiation 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 levels. Long-term follow-up is needed to consolidate these promising results.
Int J Radiat Oncol Biol Phys. 2015 Sep 1;93(1):190-5. doi: 10.1016/j.ijrobp.2015.04.049. Epub 2015 May 10.
Inter- and Intrafraction Target Motion in Highly Focused Single Vocal Cord Irradiation of T1a Larynx Cancer Patients.
Kwa SL1,
Al-Mamgani A2,
Osman SO2,
Gangsaas A2,
Levendag PC2,
Heijmen BJ2.
Author information
Abstract
PURPOSE:
The purpose of this study was to verify clinical target volume-planning target volume (CTV-PTV) margins insingle vocal cord irradiation (SVCI) of T1a larynx tumors and characterize inter- and intrafraction target motion.
METHODS AND MATERIALS:
For 42 patients, a single vocal cord was irradiated using intensity modulated radiationtherapy at a total dose of 58.1 Gy (16 fractions × 3.63 Gy). A daily cone beam computed tomography (CBCT) scan was performed to online correct the setup of the thyroid cartilage after patient positioning with in-room lasers (interfraction motion correction). To monitor intrafraction motion, CBCT scans were also acquired just after patient repositioning and after dose delivery. A mixed online-offline setup correction protocol ("O2 protocol") was designed to compensate for both inter- and intrafraction motion.
RESULTS:
Observed interfraction, systematic (Σ), and random (σ) setup errors in left-right (LR), craniocaudal (CC), and anteroposterior (AP) directions were 0.9, 2.0, and 1.1 mm and 1.0, 1.6, and 1.0 mm, respectively. After correction of these errors, the following intrafraction movements derived from the CBCT acquired after dose delivery were: Σ = 0.4, 1.3, and 0.7 mm, and σ = 0.8, 1.4, and 0.8 mm. More than half of the patients showed a systematic non-zero intrafraction shift in target position, (ie, the mean intrafraction displacement over the treatment fractions was statistically significantly different from zero; P<.05). With the applied CTV-PTV margins (for most patients 3, 5, and 3 mm in LR, CC, and AP directions, respectively), the minimum CTV dose, estimated from the target displacements observed in the last CBCT, was at least 94% of the prescribed dose for all patients and more than 98% for most patients (37 of 42). The proposed O2 protocol could effectively reduce the systematic intrafraction errors observed after dose delivery to almost zero (Σ = 0.1, 0.2, 0.2 mm).
CONCLUSIONS:
With adequate image guidance and CTV-PTV margins in LR, CC, and AP directions of 3, 5, and 3 mm, respectively, excellent target coverage in SVCI could be ensured.
Copyright © 2015 Elsevier Inc. All rights reserved.
