Intensity-Modulated Radiation Therapy for Early-Stage Squamous Cell Carcinoma of the Glottic Larynx: A Systematic Review and Meta-Analysis

Stereotactic Ablative Radiotherapy for T1 to T2 Glottic Larynx Cancer: Mature Results From the Phase 2 GLoTtic Larynx-SABR Trial

PURPOSE

Traditional radiation therapy for early-stage larynx cancer irradiates the whole larynx over 5.5 to 6 weeks. Phase 1 data suggest that stereotactic ablative radiotherapy (SABR) is a viable strategy to reduce the irradiated volume and compress treatment time. This phase 2 study evaluated the efficacy of gLoTtic larynx-SABR in 5 or 16 fractions.

METHODS AND MATERIALS

Eligibility required stage 0 to II squamous cell carcinoma of the glottic larynx. The arytenoid cartilage could not be involved beyond the vocal process, and patients smoking more than one pack per day were excluded. The treatment volume consisted of the gross tumor volume, with a 3 mm margin (5 mm craniocaudal) to create the planning target volume. Patients without active smoking and planning target volume <10 cc received 4250 cGy in 5 fractions, twice per week; other patients received 58.08 Gy in 16 daily fractions. The primary endpoint was the 2-year incidence of local failure.

RESULTS

Twenty-five patients were accrued to this study, with 21 and 4 treated with 5 and 16 fractions, respectively. The stage distribution was in situ (n = 1, 4%), T1a/b (n = 16/5, 64%/20%), and T2 (n = 3, 12%). The median age was 72 years, with a prior smoking history in 16 (64%) and active smoking in 1 (4%). At a median follow-up for surviving patients of 3.7 years (IQR, 3.1-4.4 years), there have been 2 in-field recurrences (1 in each dose cohort). The cumulative incidences of local failure were 4% (90% CI, 0.8%-20%) and 8% (90% CI, 3%-24%) at 1 and 2 years, respectively. There have been no acute or late grade 3+ toxicities in disease-free patients. The median baseline, 1, 6, 12, and 24 months Voice Handicap Index scores were 57 (IQR, 32-69), 28.5 (8-48), 4 (0-12), 7.5 (0-12), and 5 (0-24), respectively.

CONCLUSIONS

Highly conformal stereotactic radiation therapy appears safe and efficacious for early-stage glottic larynx cancer, with encouraging patient-reported outcomes. These results need to be interpreted with caution given the small sample size and large noninferiority margin. Additional follow-up and ultimately comparative studies are necessary to validate this paradigm.

Use of the 445-nm Blue Laser for Management of Early Glottic Carcinoma: Preliminary 1-Year Results

OBJECTIVE

To analyze oncological efficacy and voice outcomes of the 445-nm blue laser (BL) in the treatment of early glottic carcinoma and compare results with the 532-nm potassium-titanyl-phosphate (KTP) laser.

STUDY DESIGN

Single institution, retrospective chart review.

METHODS

All patients who underwent microlaryngoscopic KTP or BL laser excision of early glottic carcinoma from 2018 to the present day with at least 1-year follow-up were included. Primary and recurrent disease, including radiation and surgical failures, were included. Demographic data, voice outcomes and oncologic outcomes were compared between the two laser groups.

RESULTS

Forty-nine patients met the inclusion criteria for the BL group and 88 for the KTP group, with average follow-up of 635 and 1236 days, respectively. Oncologic outcomes were not significantly different, with disease-specific survival rates of 95.9% for BL and 100% for KTP (p = 0.13), organ preservation rates of 98.0% for BL and 95.6% for KTP (p = 0.39), and local control rates of 93.9% for BL and 92.1% for KTP (p = 0.81). Both BL and KTP groups showed significant improvement in CAPE-V (p = 0.04, 0.006 respectively) and VHI-10 scores (p = 0.003, <0.00001) following surgery.

CONCLUSIONS

Photoangiolytic removal of early glottic carcinoma with BL appears to be equally safe and effective as with KTP laser at minimum one-year follow-up, and with excellent voice outcomes. Additional study will be warranted over time to assess long-term outcomes in BL patients.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:4656-4660, 2024.

Patterns of Care for T1 Glottic Squamous Cell Carcinomas from 2004-2020

OBJECTIVE(S)

Describe recent national trends in overall treatment modalities for T1 glottic squamous cell carcinomas (SCC), and identify factors associated with treatment regimens.

METHODS

National Cancer Database from 2004-2020 was queried for all patients with glottic cT1N0M0 SCC. Treatment patterns over time were analyzed using the Cochran-Armitage test for trend. Multivariable logistic regressions were used to determine the factors associated with treatment regimens.

RESULTS

Of the 22,414 patients identified, most patients received RT only (57%), 21% received surgery only, and 22% received dual-modality treatment ("over-treatment"). Over the time period, there was a decreasing trend in rates of over-treatment for T1 glottic SCC (p < 0.001) and an increasing trend in surgery only (p < 0.001). Treatment in 2016-2018 (OR: 1.168 [1.004 to 1.359]), 2013-2015 (OR: 1.419 [1.221 to 1.648]), 2010-2012 (OR: 1.611 [1.388 to 1.871]), 2007-2009 (OR: 1.682 [1.450 to 1.951]), or 2004-2006 (OR: 1.795 [1.548 to 2.081]) versus 2019-2020 was associated with greater likelihood of over-treatment. T1b tumors were less likely to be over-treated (OR: 0.795 [0.707 to 0.894]) versus T1a tumors, and less likely to receive surgery first (OR: 0.536 [0.485 to 0.592]) versus T1a tumors.

CONCLUSION

Over-treatment for T1 glottic SCC has been declining, with increasing rates of surgery only. Year of treatment was significantly associated with the receipt of dual-modality treatment. Finally, patients with T1b disease were more likely to receive RT as the first and only treatment.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:3633-3644, 2024.

Dosimetric impact of VMAT delivery angles for early glottic cancer treatment

This study investigates the dosimetric effects of different gantry rotation angles used in volumetric modulated arc therapy (VMAT) for early glottic carcinoma. VMAT treatment plans using full-arc, half-arc, and partial-arc gantry rotation angles were generated from 22 computed tomography datasets of early-stage (T1-2N0) glottic laryngeal cancer. Dosimetric parameters associated with the planning target volume (PTV) and organs at risk (OARs), specifically the carotid arteries and thyroid, were compared. To assess the robustness of the VMAT plans, dose variations were analyzed by introducing positional shifts of 1, 3, and 5 mm from the isocenter of each plan along the superior-inferior, left-right, and anterior-posterior axes. Furthermore, we examined the size of the PTV, the air cavity volume within the PTV, and the variability of the beam path length through the gantry angles to investigate their correlations with PTV dose variations in the presence of positioning errors. Compared to full-arc and half-arc plans, the dosimetric parameters of partial-arc plans were found to be higher in PTV (D2%, D5%, D50%, and Dmean) and lower in OARs, while their dose variations of OAR parameters were greater for positioning errors. In addition, a correlation was observed between PTV size and PTV dose variations. Air cavity volume and depth variability were also correlated with some PTV parameters, depending on the arc plan. The results presented in this study suggest that the partial-arc gantry angles can allow higher PTV doses while minimizing OAR doses in VMAT treatment planning for early glottic cancer. However, the small delivery angles may lead to greater dose variations in the OARs when positioning errors occur.