Intensity-modulated radiation therapy in early stage squamous cell carcinoma of the larynx: treatment trends and outcomes

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.

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, 2024.

Long-Term Follow-up of a Randomized Controlled Trial on Accelerated Radiation Therapy Versus Standard Fractionated Radiation Therapy for Early Glottic Cancer (JCOG0701A3)

PURPOSE

We previously reported the primary results of JCOG0701, a randomized, multicenter, phase 3, noninferiority trial comparing accelerated fractionation (Ax) to standard fractionation (SF) for early glottic cancer. In the primary results, although the similar efficacy of 3-year progression-free survival and toxicity of Ax compared with SF was observed, the noninferiority of Ax was not confirmed statistically. To evaluate the long-term follow-up results of JCOG0701, we conducted JCOG0701A3 as an ancillary study of JCOG0701.

METHODS AND MATERIALS

In JCOG0701, 370 patients were randomly assigned to receive SF of 66 to 70 Gy (33-35 fractions; n = 184) or Ax of 60 to 64.8 Gy (25-27 fractions; n = 186). The data cutoff date for this analysis was in June 2020. Overall survival, progression-free survival, and late adverse events including central nervous system ischemia were analyzed.

RESULTS

With a median follow-up period of 7.1 years (range, 0.1-12.4), progression-free survival of the SF and Ax arms were 76.2% and 78.2% at 5 years and 72.7% and 74.8% at 7 years (P = .44). OS of the SF and Ax arms were 92.7% and 89.6% at 5 years and 90.8% and 86.5% at 7 years (P = .92). Among 366 patients with a protocol treatment, the cumulative incidence of late adverse events of the SF and Ax arms were 11.9% and 7.4% at 8 years (hazard ratio, 0.53; 95% CI, 0.28-1.01; P = .06). Central nervous system ischemia of grade 2 or higher was observed in 4.1% for the SF arm and 1.1% for the Ax arm (P = .098).

CONCLUSIONS

After long-term follow-up, Ax showed comparable efficacy to SF and a tendency for better safety. Ax may be suitable for early glottic cancer because of its convenience in minimizing treatment time, cost, and labor.

Early-Stage Glottic Carcinoma in the United States: Demographics and Treatment Choice

OBJECTIVE

Limited investigation of factors potentially contributing to treatment choice in early-stage glottic carcinoma (EGC) has been performed with large-scale data. The National Cancer Database (NCDB) represents >72% of all new cancer cases in the United States. We hypothesized that NCDB variables may lend insight into treatment decisions between surgery and radiation for EGC.

METHODS

The NCDB was queried for all cases of T_1-2  N₀  M₀ glottic carcinoma from 2004 to 2016. We used multivariable logistic regression analysis to examine factors associated with first-line treatment modality: radiation therapy (RT) versus surgery. All reported odds ratios (OR) were adjusted for age, gender, race, insurance, residence in a metropolitan area, region, and facility volume.

RESULTS

34,991 EGC patients received treatment: 6,687 (19%) surgery; 20,289 (58%) RT; and 8,015 (23%) surgery and RT. OR for receiving RT (vs. surgery alone) were >2 for: more advanced T stage cancers (OR 2.5 [95%CI: 2.3, 2.7]), treatment at non-academic facilities (OR 2.8, [95%CI: 2.6, 3.0]), and shorter travel distances to treatment centers (OR 2.2, [95%CI: 2.0, 2.4]). Surgery was more likely with treatment in the western US, higher income, private insurance, living in a metropolitan (vs. non-metropolitan) area, female gender, older age, and low facility volume. Hispanic ethnicity, education level, and race were not associated with treatment type in the multivariable model.

CONCLUSION

Most patients in the NCDB receive first-line treatment with radiation for EGC, and this decision is associated with various tumor, patient, and treatment facility characteristics.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:901-907, 2023.

Organ-at-risk sparing with dynamic trajectory radiotherapy for head and neck cancer: comparison with volumetric arc therapy on a publicly available library of cases

Background

Dynamic trajectory radiotherapy (DTRT) extends volumetric modulated arc therapy (VMAT) with dynamic table and collimator rotation during beam-on. The aim of the study is to establish DTRT path-finding strategies, demonstrate deliverability and dosimetric accuracy and compare DTRT to state-of-the-art VMAT for common head and neck (HN) cancer cases.

Methods

A publicly available library of seven HN cases was created on an anthropomorphic phantom with all relevant organs-at-risk (OARs) delineated. DTRT plans were generated with beam incidences minimizing fractional target/OAR volume overlap and compared to VMAT. Deliverability and dosimetric validation was carried out on the phantom.

Results

DTRT and VMAT had similar target coverage. For three locoregionally advanced oropharyngeal carcinomas and one adenoid cystic carcinoma, mean dose to the contralateral salivary glands, pharynx and oral cavity was reduced by 2.5, 1.7 and 3.1 Gy respectively on average with DTRT compared to VMAT. For a locally recurrent nasopharyngeal carcinoma, D_0.03 cc to the ipsilateral optic nerve was above tolerance (54.0 Gy) for VMAT (54.8 Gy) but within tolerance for DTRT (53.3 Gy). For a laryngeal carcinoma, DTRT resulted in higher dose than VMAT to the pharynx and brachial plexus but lower dose to the upper oesophagus, thyroid gland and contralateral carotid artery. For a single vocal cord irradiation case, DTRT spared most OARs better than VMAT. All plans were delivered successfully on the phantom and dosimetric validation resulted in gamma passing rates of 93.9% and 95.8% (2%/2 mm criteria, 10% dose threshold).

Conclusions

This study provides a proof of principle of DTRT for common HN cases with plans that were deliverable on a C-arm linac with high accuracy. The comparison with VMAT indicates substantial OAR sparing could be achieved.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13014-022-02092-5.

Radiation Oncology Alternative Payment Model and Large Urban Academic Centers: Future Implications for Patients and Providers

The radiation oncology alternative payment model (RO-APM) was developed by the Center for Medicare and Medicaid Innovation, a part of the Centers for Medicare & Medicaid Services, as a vehicle to optimize value for patients undergoing radiation therapy. By shifting reimbursement away from fee-for-service and toward a prospective bundled payment system, the RO-APM is intended to bend the cost curve in radiation oncology while preserving or even enhancing outcomes. As with prior large-scale policy initiatives, the nature and magnitude of the RO-APM's impact on care delivery will vary substantially depending on a host of local factors, including practice setting. Urban academic centers play a key role in radiation oncology by spearheading innovation, managing the most complicated cases, training the next generation of radiation oncologists, and often caring for vulnerable patient populations. Thus, to protect patients' access to this high-quality cancer care, it will be crucial to characterize the RO-APM's projected impact on large urban academic institutions before its implementation, including possible unintended adverse consequences. Here, we provide an overview of this seismic change in radiation oncology reimbursement and discuss its unique potential implications for large urban academic institutions as a means to facilitate necessary preparations and inform future revisions to the model.

Early-Stage Glottic Squamous Cell Carcinoma in the Era of Image-Guided Radiotherapy

Early-stage squamous cell cancer (SCC) of the glottis has a good prognosis. Therefore, patients have long survival outcomes and may potentially suffer from late toxicities of radiotherapy. Radiotherapy with a conventional parallel-opposed-pair or anterior-oblique beam arrangements for stage 1 and 2 glottic SCC have field borders that traditionally cover the entire larynx, exposing organs-at-risk (e.g. carotid arteries, contralateral vocal cord, contralateral arytenoid and inferior pharyngeal constrictor muscles) to high radiation doses. The potential long-term risk of cerebrovascular events has attracted much attention to the dose that carotid arteries receive. Swallow and respiratory motion of laryngeal structures has been an important factor that previously limited reduction of the radiation treatment volume. Motion has been evaluated using multiple imaging modalities and this information has been used to calculate PTV margins for generation of more limited target volumes. This review discusses the current literature surrounding dose-effect relationships for various organs-at-risk and the late toxicities that are associated with them. This article also reviews the currently available data and effects of laryngeal motions on dosimetry to the primary target. We also review the current limitations and benefits of a more targeted approach of radiotherapy for early-stage glottic SCCs and the evolution of CT-based IGRT and MR-guided radiotherapy techniques that may facilitate a shift away from a conventional 3D-conformal radiotherapy approach.

Outcomes between intensity-modulated radiation therapy versus 3D-conformal in early stage glottic cancer

BACKGROUND

The purpose of this study is to evaluate practice patterns and outcomes between intensity-modulated radiation therapy (IMRT) and 3D-conformal radiation (3D-CRT) in early stage glottic cancer.

METHODS

The linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database was used to identify and compare patient and disease profiles, mortality, and toxicity in patients with T1-2 larynx cancer undergoing definitive radiation (RT).

RESULTS

A total of 1520 patients underwent definitive radiation with 3D-CRT (n = 1309) or IMRT (n = 211). Non-white race, those with a Charlson Comorbidity Index ≥2, T2 disease, and those treated at community practices were more likely to undergo IMRT. Rates of IMRT increased from 2006 to 2015, while relative rates of 3D-CRT decreased. Two-year CSS was superior with 3D-CRT (hazard ratio [HR], 0.38; 95% confidence interval [CI], 0.22-0.65; p < 0.001). There was no difference in OS between 3D-CRT and IMRT (p = 0.119).

CONCLUSIONS

Patients receiving 3D-CRT had improved CSS compared to IMRT with no difference in OS.

Radiotherapy in the management of glottic squamous cell carcinoma

INTRODUCTION

Our purpose is to review the role radiotherapy (RT) in the treatment of glottic squamous cell carcinoma (SCC).

METHODS

A concise review of the pertinent literature.

RESULTS

RT cure rates are Tis- T1N0, 90% to 95%; T2N0, 70% to 80%; low-volume T3-T4a, 65% to 70%. Concomitant cisplatin is given for T3-T4a SCCs. Severe complications occur in 1% to 2% for Tis-T2N0 and 10% for T3-T4a SCCs. Patients with high-volume T3-T4 SCCs undergo total laryngectomy, neck dissection, and postoperative RT. Those with positive margins and/or extranodal extension receive concomitant cisplatin. The likelihood of local-regional control at 5 years is 85% to 90%. Severe complications occur in 5% to 10%.

CONCLUSIONS

RT is a good treatment option for patients with Tis-T2N0 and low-volume T3-T4a glottic SCCs. Patients with higher volume T3-T4 cancers are best treated with surgery and postoperative RT.

Occult Lymph Node Metastasis in Early-Stage Glottic Cancer in the National Cancer Database

OBJECTIVES

Early-stage glottic cancer (cT1-T2 cN0) may be treated by primary surgery or radiation. Elective treatment of the neck in clinically N0 disease is usually not performed due to low rates of regional lymph node metastasis. This study examines the role of elective neck dissection (END) and rate of occult nodal metastasis in cT1-T2 cN0 glottic cancer treated with primary surgery.

STUDY DESIGN

Retrospective cohort study.

METHODS

The National Cancer Database was used to identify patients treated for early-stage glottic cancer. Demographic variables, disease characteristics, and overall survival were compared between the subgroups of patients who did and did not receive END. Factors predictive of occult lymph node metastasis were also identified using a multivariate logistic regression model.

RESULTS

Thirty-eight percent of the 991 patients in this cohort underwent END. Younger age, treatment at an academic facility, advanced T-stage, and higher tumor grade were associated with receiving END. Sixteen percent of the 372 patients undergoing END had occult nodal metastasis. Higher tumor histopathologic grade was associated with occult metastasis (P = .004). While undergoing END did not affect significantly survival, those with occult metastasis had poorer survival (P < .001).

CONCLUSIONS

END should be considered in cT1-T2 N0 glottic cancers with poorly differentiated or undifferentiated tumor histopathology. While END itself may not improve overall survival, identification of occult nodal metastasis is an important finding for prognostication.

LEVEL OF EVIDENCE

Level 3 Laryngoscope, 131:E1139-E1146, 2021.