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

Assessment and validation of glottic motion using cone-beam CT and real-time cine MRI

PURPOSE

This study aimed to assess the margin for the planning target volume (PTV) using the Van Herk formula. We then validated the proposed margin by real-time magnetic resonance imaging (MRI).

METHODS

An analysis of cone-beam computed tomography (CBCT) data from early glottic cancer patients was performed to evaluate organ motion. Deformed clinical target volumes (CTV) after rigid registration were acquired using the Velocity program (Varian Medical Systems, Palo Alto, CA, USA). Systematic (Σ) and random errors (σ) were evaluated. The margin for the PTV was defined as 2.5 Σ + 0.7 σ according to the Van Herk formula. To validate this margin, we accrued healthy volunteers. Sagittal real-time cine MRI was conducted using the ViewRay system (ViewRay Inc., Oakwood Village, OH, USA). Within the obtained sagittal images, the vocal cord was delineated. The movement of the vocal cord was summed up and considered as the internal target volume (ITV). We then assessed the degree of overlap between the ITV and the PTV (vocal cord plus margins) by calculating the volume overlap ratio, represented as (ITV∩PTV)/ITV.

RESULTS

CBCTs of 17 early glottic patients were analyzed. Σ and σ were 0.55 and 0.57 for left-right (LR), 0.70 and 0.60 for anterior-posterior (AP), and 1.84 and 1.04 for superior-inferior (SI), respectively. The calculated margin was 1.8 mm (LR), 2.2 mm (AP), and 5.3 mm (SI). Four healthy volunteers participated for validation. A margin of 3 mm (AP) and 5 mm (SI) was applied to the vocal cord as the PTV. The average volume overlap ratio between ITV and PTV was 0.92 (range 0.85-0.99) without swallowing and 0.77 (range 0.70-0.88) with swallowing.

CONCLUSION

By evaluating organ motion by using CBCT, the margin was 1.8 (LR), 2.2 (AP), and 5.3 mm (SI). The margin acquired using CBCT fitted well in real-time cine MRI. Given that swallowing during radiotherapy can result in a substantial displacement, it is crucial to consider strategies aimed at minimizing swallowing and related motion.

The Evolving Role of Stereotactic Body Radiation Therapy for Head and Neck Cancer: Where Do We Stand?

Stereotactic body radiation therapy (SBRT) is a precise and conformal radiation therapy (RT) that aims to deliver a high dose of radiation to the tumor whilst sparing surrounding normal tissue, making it an attractive option for head and neck cancer (HNC) patients who are not suitable for the traditional long course of RT with comprehensive RT target volume. Definitive SBRT for HNC has been investigated in different settings, including early stage glottis cancer, and as an alternative to brachytherapy boost after external beam RT. It is also used as a primary treatment option for elderly or medically unfit patients. More recently, an SBRT combination with immunotherapy in the neoadjuvant setting for HNC showed promising results. Salvage or adjuvant SBRT for HNC can be used in appropriately selected cases. Future studies are warranted to determine the optimum dose and fractionation schedules in any of these indications.

Real-Time Tracking of Laryngeal Motion via the Surface Depth-Sensing Technique for Radiotherapy in Laryngeal Cancer Patients

Radiotherapy (RT) is an important modality for laryngeal cancer treatment to preserve laryngeal function. During beam delivery, laryngeal motion remains uncontrollable and may compromise tumor-targeting efficacy. We aimed to examine real-time laryngeal motion by developing a surface depth-sensing technique with preliminary testing during RT-based treatment of patients with laryngeal cancer. A surface depth-sensing (SDS) camera was set up and integrated into RT simulation procedures. By recording the natural swallowing of patients, SDS calculation was performed using the Pose Estimation Model and deep neural network technique. Seven male patients with laryngeal cancer were enrolled in this prospective study. The calculated motion distances of the laryngeal prominence (mean ± standard deviation) were 1.6 ± 0.8 mm, 21.4 ± 5.1 mm, 6.4 ± 3.3 mm, and 22.7 ± 4.9 mm in the left-right, cranio-caudal, and anterior-posterior directions and for the spatial displacement, respectively. The calculated differences in the 3D margins for generating the planning tumor volume by senior physicians with and without SDS data were -0.7 ± 1.0 mm (-18%), 11.3 ± 6.8 mm (235%), and 1.8 ± 2.6 mm (45%) in the left-right, cranio-caudal, and anterior-posterior directions, respectively. The SDS technique developed for detecting laryngeal motion during swallowing may be a practical guide for individualized RT design in the treatment of laryngeal cancer.

Effect of 0.35 T and 1.5 T magnetic fields on superficial dose in MR-guided radiotherapy of laryngeal cancer

Background

Treatment of head and neck cancer on linear accelerators with on-board magnetic resonance imaging (MR-linac) might be beneficial to reduce side effects and increase accuracy. For many head and neck cancer patients, dose coverage of the often superficially located planning target volumes (PTVs) is required. This study examines the impact of the electron return effect (ERE) on the surface dose in MR-guided radiotherapy (MRgRT) compared to conventional radiotherapy.

Materials and methods

For this bicentric dosimetric study, 14 cases of laryngeal carcinomas with PTVs reaching up to the skin surface were included. For each patient, five different plans were compared, two VMAT plans (with and without a 5 mm bolus) and three IMRT MRgRT plans (0.35 T, 1.5 T and 0 T, each without bolus). Dose distributions were also validated with film measurements.

Results

A similar coverage on the most superficial 3-5 mm of the PTV was achieved in the VMAT plans with bolus and the MRgRT plans for both 0.35 T and 1.5 T. However, coverage on this region was usually not achieved for VMAT without bolus and the 0 T plans. The film measurements on phantoms confirmed the results with the relative error never exceeding the calculated differences between the plans.

Conclusion

The present study could demonstrate that the ERE for both commercially available MR-linac variants provides sufficient coverage of the superficial tissue layers in MRgRT-plans for laryngeal carcinoma.

VoiceS: voice quality after transoral CO2 laser surgery versus single vocal cord irradiation for unilateral stage 0 and I glottic larynx cancer-a randomized phase III trial

Background

Surgery and radiotherapy are well-established standards of care for unilateral stage 0 and I early-stage glottic cancer (ESGC). Based on comparative studies and meta-analyses, functional and oncological outcomes after both treatment modalities are similar. Historically, radiotherapy (RT) has been performed by irradiation of the whole larynx. However, only the involved vocal cord is being treated with recently introduced hypofractionated concepts that result in 8 to 10-fold smaller target volumes. Retrospective data argues for an improvement in voice quality with non-inferior local control. Based on these findings, single vocal cord irradiation (SVCI) has been implemented as a routine approach in some institutions for ESGC in recent years. However, prospective data directly comparing SVCI with surgery is lacking. The aim of VoiceS is to fill this gap.

Methods

In this prospective randomized multi-center open-label phase III study with a superiority design, 34 patients with histopathologically confirmed, untreated, unilateral stage 0-I ESGC (unilateral cTis or cT1a) will be randomized to SVCI or transoral CO₂-laser microsurgical cordectomy (TLM). Average difference in voice quality, measured by using the voice handicap index (VHI) will be modeled over four time points (6, 12, 18, and 24 months). Primary endpoint of this study will be the patient-reported subjective voice quality between 6 to 24 months after randomization. Secondary endpoints will include perceptual impression of the voice via roughness – breathiness – hoarseness (RBH) assessment at the above-mentioned time points. Additionally, quantitative characteristics of voice, loco-regional tumor control at 2 and 5 years, and treatment toxicity at 2 and 5 years based on CTCAE v.5.0 will be reported.

Discussion

To our knowledge, VoiceS is the first randomized phase III trial comparing SVCI with TLM. Results of this study may lead to improved decision-making in the treatment of ESGC.

Trial registration

ClinicalTrials.gov NCT04057209. Registered on 15 August 2019. Cantonal Ethics Committee KEK-BE 2019-01506

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06841-5.

Hypofractionated radiotherapy for early stage glottic cancer: efficacy of 3.5 Gy per fraction

Purpose

The purpose of this study was to evaluate the treatment outcomes and toxicity profile of patients with early glottic cancer who underwent hypofractionated radiation therapy (RT) with 3.5 Gy per fraction.

Materials and Methods

A retrospective review was performed of the medical records of 35 patients with early stage (T1-2N0M0) glottic cancer who underwent definitive RT. The dose fractionation scheme was 59.5 Gy in 17 fractions. Posterior commissure was excluded from the clinical target volume (CTV) for 26 patients (74.3%) without glottic lesions close to this region.

Results

With a median follow-up of 16.23 months (range, 6.82 to 67.15 months), no local, regional, or distant recurrence was reported. Acute hoarseness (65.7%), mucositis (68.6%), radiation dermatitis (60.0%) was frequent. One patient (2.9%) reported grade 3 acute toxicity (mucositis) and there was no grade 4–5 acute toxicity. There was no grade ≥3 late toxicities; however, grade 1 late intermittent hoarseness was frequent (45.7%). The receiver operative characteristic analysis revealed that mean hypopharyngeal dose was predictive for acute grade ≥2 mucositis (area under the curve=0.9314; 95% confidence interval, 0.8524–1). The optimal threshold of mean hypopharyngeal dose for occurrence of acute grade ≥2 mucositis was 26.31 Gy, with a specificity and sensitivity of 83.3% and 88.2%, respectively.

Conclusion

Hypofractionated RT with fraction size of 3.5 Gy for early glottic cancer is effective. The hypopharyngeal mean dose could predict the occurrence of grade ≥2 acute mucositis. The posterior commissure can be safely excluded from the CTV.

Advances in Organ Preservation for Laryngeal Cancer

OPINION STATEMENT

At the University of Wisconsin, all treatment of head and neck cancer patients begins with discussion at our multi-disciplinary tumor board. Most patients with T4 disease, with existing laryngeal dysfunction, considered unlikely to complete definitive CRT or who have a high risk of persistent aspiration after non-operative management undergo total laryngectomy. A laryngeal sparing approach is attempted on most other patients. Radiotherapy is delivered over 6.5 weeks, preferably with concurrent weekly cisplatin. If the patient is hesitant of chemotherapy or has contraindications to cisplatin, concurrent cetuximab may be offered. Patients treated with RT alone are often treated to the same dose, but via an accelerated schedule by adding a 6th fraction per week. The 6th fraction is given by delivering two treatments at least 6 h apart on a weekday of the patient's choosing. We consider the following to be major risk factors for clinically significant weight loss during treatment: a 10% or greater loss of weight in the 6 months prior to starting treatment, delivery of concurrent cisplatin, and treatment of the bilateral neck with radiation. Patients who have 2-3 of these characteristics are often given gastrostomy tubes prophylactically. Patients are seen 2 weeks after completion of therapy, and then every 3 months after completion for 2 years. A CT neck and PET-CT are performed at the first 3-month visit. They are seen twice in year three, and then yearly until years 5-7. At each of these visits, we have a low threshold to present the patient at our multidisciplinary tumor board for consideration of salvage laryngectomy if there are signs of progression.

Single vocal cord irradiation for early-stage glottic cancer: Excellent local control and favorable toxicity profile

OBJECTIVE

To validate the earlier reported promising oncologic outcomes and favorable toxicity profile following single vocal cord irradiation (SVCI) in an expanded cohort of patients with early-stage glottic cancer treated at our institute with longer follow-up time.

MATERIALS AND METHODS

Between February 2011 and January 2020, 111 consecutive patients with early-stage glottic cancer were treated with SVCI to the whole involved vocal cord (58.08 Gy, given in 16 fractions of 3.63 Gy). Setup verification was done using cone-beam CT, prior to each fraction. The endpoints were local control (LC), overall survival (OS), grade ≥ 3 toxicity and voice quality assessment using voice-handicap index (VHI) questionnaires.

RESULTS

Median follow-up was 41 months (range; 8-84). Two patients developed in-field local failure (LF). The 3- and 5-year LC rates were 99.1% and 97.1%, respectively. As both patients with LF were successfully salvaged with total laryngectomy, the 5-year ultimate LC-rates was 99%. The 5-years OS was 80.6%. All patients finished treatment without any interruption. No patients developed acute grade ≥ 3 toxicity. Late grade 3 toxicity was reported in 7 patients (6.5%) out of 108 patients evaluable for late toxicity; 2 because of severe hoarseness and 5 because of laryngeal radionecrosis (4.5%). The 5-years laryngectomy-free survival was 98.1%. The VHI-scores improved over time, only 22% of patients had VHI > 30 at 3-years post-radiotherapy, compared to 38% at baseline.

CONCLUSIONS

Local control rate and laryngectomy-free survival of SVCI are excellent with favorable toxicity profile and good VHI-score. These results validate our early results.

[Radiotherapy for patients with early-stage glottic squamous cell carcinoma of the larynx: Interest of hypofractionation?]

Hypofractionated radiotherapy of early-stage squamous cell carcinoma of the glottic larynx is a promising treatment option. This can be divided into radiotherapy with moderate hypofractionation (up to 2.5Gy per fraction), more intense hypofractionation (between 2.5 and 4.5Gy per fraction) and stereotactic radiotherapy (above 4.5Gy per fraction). Most studies evaluating moderate hypofractionation show a local control rate between 85 and 95%. Acute laryngeal toxicity is superior to conventional treatment, but only for grades 1 and 2, with no significant difference reported for severe toxicity. Stereotactic radiotherapy in this pathology is also an emerging entity, but some authors have reported significant toxicity. There are currently no standardized guidelines for treatment and management regimen. We conducted a systemic review of published prospective and retrospective trials to evaluate efficacy, toxicity, and discuss future directions.

Stereotactic body radiotherapy for T1 glottic cancer: dosimetric data in 27 consecutive patients

AIM

Because the clinical feasibility of stereotactic body radiotherapy (SBRT) for early glottic cancer (T1) is controversial, we report dosimetric results in 27 consecutive patients from a prospective phase I and II study that started in 2017.

METHODS

In our approach, only the parts of the true vocal cord containing cancer and those immediately adjacent are planned to be treated to 36 Gy and 30 Gy, respectively, in 3 fractions. Several dosimetric metrics for both target volumes and organs at risk were extracted from individual plans and results were compared to those achieved by other authors in a similar setting.

RESULTS

Proper coverage was reached at planning in 2/3 of planning treatment volume 30 Gy, but only 4 planning treatment volume 36 Gy; conversely, the maximum dose objective was met for most of the patients on either arytenoid cartilage, but this was not the case for 51.9% and 96.3% of cricoid and thyroid cartilages, respectively. Our dosimetric results are similar to if not better than those achieved by others.

CONCLUSION

SBRT in 3 fractions for T1 glottic lesions is dosimetrically challenging. Clinical validation is awaited.

Stereotactic body radiotherapy (SBRT) for primary non-metastatic head and neck cancer: When less is enough

The advantage of highly conformal dose distribution and steep dose gradient has resulted in rapidly increasing use of stereotactic body radiotherapy (SBRT) in multiple cancer sites. Also there has been a surge in the use of SBRT in head neck cancer over the last decade. It is predominantly exploited in retreatment setting for recurrent and second primary head neck cancer as well as in metastatic setting. The literature on SBRT in primary non-metastatic head neck cancer is sparse and evolving. In the current review, available literature was critically analyzed focusing on the potential applications of SBRT in primary untreated non-metastatic head neck cancer. SBRT boost following external beam radiotherapy is temping as a method of dose escalation. Special attention was paid to the application of SBRT as a sole modality of treatment. The shorter treatment schedule makes it an attractive option for treatment in primary head neck cancer especially in elderly, co-morbid and medically unfits patients. Future investigation is needed to establish SBRT as an additional armamentarium in the radiotherapeutic management of head and neck cancers.

Stereotactic Radiation Therapy for De Novo Head and Neck Cancers: A Systematic Review and Meta-Analysis

Purpose

Stereotactic body radiation therapy (SBRT) for de novo (previously untreated) head and neck cancers (HNCs) is increasingly being used in medically unfit patients. A systematic review of SBRT was conducted for previously untreated HNCs.

Methods and Materials

Medline (PubMed), excerpta medica database, and Cochrane Library databases were queried from inception until July 2020. Comparative outcome data were extracted where available up to 5 years. Results from random-effect models were presented in forest plots, with between-study heterogeneity evaluated by I² statistics and Q-tests.

Results

Nine studies met inclusion criteria, representing 157 patients. Local control rates at 1, 2, and 3 years were as follows: 90.7% (95% confidence interval, 80.6%-95.6%), 81.8% (67.2%-90.7%), and 73.5% (40.4%-90.5%), respectively. Overall survival at 1, 2, and 3 years was 75.9% (75.1%-76.6%), 61.1% (60.3%-61.9%), and 50.0% (48.8%-51.4%), respectively. Late grade 3 to 4 toxicity rate was 3.3% (0.2%-10.2%), and late grade 5 toxicity rate was 0.1% (0.0%-1.0%).

Conclusions

SBRT for de novo HNC is safe and effective in providing locoregional control, with acceptable toxicities in most subsites. This finding warrants broader validation to guide its scope.

Is Single Cord Irradiation Going to Be a New Standard for T1a Glottic Carcinoma?

Purpose and Objective: To evaluate the disease-free survival, overall survival, dosimetric, and voice handicap index (VHI) results of T1a glottic invasive squamous cell carcinoma (SCC) patients who underwent hypofractionated single vocal cord irradiation (HSVCI).

Materials and Methods: The data of 18 patients with stage T1a glottic SCC were collected prospectively and analyzed retrospectively between July 2016 and July 2019. Patients were immobilized using a custom-fitted thermoplastic face and shoulder mask in hyperextension position. The CT scan was performed with 1-mm-thick slices. A planned target volume (PTV) margin of 3 mm was given to clinical target volume (CTV) in all directions, and 13 organs at risk were identified. Patients were prescribed a total of 5760–5808 cGy in 15–16 fractions. Patients had daily cone-beam computed tomography (CBCT), and the treatment was carried out with the physician. VHI test was applied to patients before and at the end of radiotherapy (RT) and 1, 2, 3, 4, and 6 months after the completion of RT.

Results: Local control and overall survival rate is 100% for a median of 18 months (6–44 months) of follow-up. A patient was diagnosed with 2nd primary lung cancer and active treatment still continues. All patients completed the treatment within the scheduled time. Grade 1–2 dysphagia and dermatitis occurred in all patients, and no grade 3 and above side effects were observed. The mean values of VHI were 37.00, 39.83, 38.28, 17.17, 12.22, 8.56, and 6.06 at the beginning of RT, at the end of RT, and 1, 2, 3, 4, and 6 months after RT, respectively.

Conclusion: Compared to surgery and conventional laryngeal radiotherapy, HSVCI is an alternative treatment method for T1a glottic cancer by reducing the treatment time to 3 weeks, facilitating recurrence treatment, and providing effective sound quality without compromising local control. Considering that ~80% of recurrences in glottic cancer occur within the first 2 years, 100% local control in a median of 18 months is extremely successful, but long-term follow-up is essential to observe possible late side effects.

Emerging Concepts and Novel Strategies in Radiation Therapy for Laryngeal Cancer Management

Laryngeal squamous cell carcinoma is the second most common head and neck cancer. Its pathogenesis is strongly associated with smoking. The management of this disease is challenging and mandates multidisciplinary care. Currently, accepted treatment modalities include surgery, radiation therapy, and chemotherapy—all focused on improving survival while preserving organ function. Despite changes in smoking patterns resulting in a declining incidence of laryngeal cancer, the overall outcomes for this disease have not improved in the recent past, likely due to changes in treatment patterns and treatment-related toxicities. Here, we review emerging concepts and novel strategies in the use of radiation therapy in the management of laryngeal squamous cell carcinoma that could improve the relationship between tumor control and normal tissue damage (therapeutic ratio).