Hypofractionated radiotherapy for early glottic cancer: a retrospective interim analysis of a single institution

Outcomes of hypofractionation for early-stage glottic carcinoma

BACKGROUND

Our goal is to evaluate hypofractionation in early-stage glottic carcinoma of a single center in line with randomized trials.

MATERIALS AND METHODS

Between June 2016 and January 2021, 33 early glottic carcinoma patients treated with IMRT (intensity-modulated radiotherapy) in the Radiation Oncology Department were analyzed. Descriptive statistics and survival analysis were applied. Survival analysis and curves were done via the Kaplan-Meier method. Survival curves were analyzed due to the T stage. Log-rank test was used for the analysis of T stage survival curves.

RESULTS

Twenty (60.1%) patients were T1 whereas six (18.2%) and seven (21.2%) were Tis. 56.25 Gy, 63 Gy, and 65.25 Gy were delivered to the patients with Tis, T1, and T2, respectively. All groups were treated with 2.25 Gy per fraction. T2 stage had lesser DFS (disease-free survival) compared to Tis and T1 stage and it was statistically significant (P = 0.035).

CONCLUSION

Hypofractionation with 2.25 Gy per fraction may be standard for early glottic carcinoma with similar results compared to microsurgery and conventional fractionation radiotherapy.

Hypofractionated (2.75 Gy per fraction) versus Conventionally Fractionated Primary Radiotherapy for T2N0M0 Carcinoma of the Glottis

Introduction  Radiotherapy provides excellent outcome in early stage glottic cancer; however, the optimal radiotherapy dose fractionation remains unknown. Objective  To investigate the outcome of patients with T2N0M0 treated with either hypofractionated (HypoFxn) or conventionally fractionated radical (ConFxn) radiotherapy. Methods  According to our institutional protocol, patients with T2N0M0 glottic cancer can be treated either with ConfFxn or HypoFxn radiotherapy, as per clinician's and patient's choice, following shared decision making discussing the advantages and disadvantages of both modalities. A total of 77 patients with T2N0M0 squamous cell carcinoma of glottis treated with either HypoFxn 55Gy in 20 fractions ( n  = 19) or ConFxn 63 to 65Gy in 30 fractions ( n  = 58) were included. Results  With median follow-up of 3.4 years, there was no significant difference in disease-free survival (median: HypoFxn = 65.2 months, and ConFxn = 75.3 months; p  = 0.874), local recurrence free survival rates (median: HypoFxn = 78.8 months vs. ConFxn = 81.2 months; p  = 0.274), and overall survival (median: HypoFxn = 65.9 months vs. ConFxn = 67.7 months; p  = 0.532). Elective neck irradiation was given to 43 patients, all in the ConFxn group, and this was associated with poorer local control ( p  = 0.027). The use of radiotherapy modality, three-dimensional conformal radiotherapy (3DRT) versus intensity modulated radiotherapy (IMRT), was not a prognostic factor ( p  = 0.36). In the HypoFxn group, grade III acute dysphagia requiring nasogastric tube was 16%, compared with 25% in the ConFxn group ( p  = 0.446). Conclusion  HypoFxn radiotherapy provides a comparable treatment outcome with acceptable toxicity. The addition of prophylactic irradiation of the neck lymph nodes has no impact on regional control.

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.

[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.

Prediction of VMAT delivery accuracy with textural features calculated from fluence maps

Background

Comprehensively textural feature performance test from volumetric modulated arc therapy (VMAT) fluences to predict plan delivery accuracy.

Methods

A total of 240 VMAT plans for various treatment sites were analyzed, with Trilogy and TrueBeam STx systems. Fluence maps superposed fluences at each control point per plan. The textural features were the angular second moment (ASM), inverse difference moment (IDM), contrast, variance, correlation, and entropy, calculated from fluence maps using three displacement distances. Correlation analysis of textural feature performance as predictors of VMAT delivery accuracy used global gamma passing rates with MapCHECK2 and ArcCHECK dosimeters, and mechanical delivery errors calculated from machine log files.

Results

Spearman’s rank correlation coefficients (r) of the ASM (d = 10) to the gamma passing rates with 1%/2 mm using the MapCHECK2 were 0.358 and 0.519, respectively (p <  0.001). For the ArcCHECK, they were 0.273 (p = 0.001) and 0.259 (p = 0.009), respectively. The r-values of the ASM (d = 10) to the Trilogy and TrueBeam STx MLC errors were − 0.843 and − 0.859, respectively (p <  0.001), and those to the MU delivery errors were − 0.482 and − 0.589, respectively (p <  0.001). The ASM (d = 10) showed better performance in predicting VMAT delivery accuracy.

Conclusions

The ASM (d = 10) calculated from VMAT plan fluence maps were strongly correlated with global gamma passing rates and MLC delivery errors, and can predict VMAT delivery accuracy.