Radiosurgery Society Case-Based Guide to Stereotactic Body Radiation Therapy for Challenging Cases of Spinal Metastases.

PURPOSE: Spinal stereotactic body radiation therapy (SBRT) has become the standard of care in management of patients with limited sites of metastatic disease, radio-resistant histologies, painful vertebral metastases with long life expectancy and cases of reirradiation. Our case-based guidelines aim to assist radiation oncologists in the appropriate utilization of SBRT for common, yet challenging, cases of spinal metastases. MATERIALS AND METHODS: Cases were selected to include scenarios of large volume sacral disease with nerve entrapment, medically inoperable disease abutting the thecal sac, and local failure after prior SBRT. Relevant literature was reviewed, and areas requiring further investigation were discussed to offer a framework for evidence-based clinical practice. RESULTS: Spinal SBRT can be effectively delivered in challenging cases following multidisciplinary discussion by utilizing a methodical approach to patient selection, appropriate dose selection, and adherence to evidence-based dose constraints. CONCLUSIONS: The Radiosurgery Society's case-based practice review offers guidance to practicing physicians treating technically challenging SBRT candidate patients with spinal metastases.

A Case-based Guide for World Health Organization (WHO) Grade 2 Meningioma Radiosurgery and Radiation Therapy from The Radiosurgery Society.

PURPOSE: Meningiomas represent the most common primary tumor of the central nervous system. Current treatment options include surgical resection with or without adjuvant radiation therapy (RT), definitive RT, and observation. However, the radiation dose, fractionation, and margins used to treat patients with WHO grade 2 meningiomas, which account for approximately 20% of all meningiomas, are not clearly defined, and deciding on the optimal treatment modality can be challenging owing to the lack of randomized data. METHODS AND MATERIALS: In this manuscript, 3 cases of patients with WHO grade 2 meningiomas are presented with descriptions of treatment options after gross total resection, subtotal resection, and previous irradiation. Treatment recommendations were compiled from 9 central nervous system radiation oncology and neurosurgery experts from The Radiosurgery Society, and the consensus of treatment recommendations is reported. RESULTS: Both conventional and stereotactic RT are treatment options for WHO grade 2 meningiomas. The majority of prospective data in the setting of WHO grade 2 meningiomas involve larger margins. Stereotactic radiosurgery/hypofractionated stereotactic RT are less appropriate in this setting. Conventionally fractionated RT to at least 59.4 Gy is considered standard of care with utilization of preoperative and postoperative imaging to evaluate the extent of disease and possible osseous involvement. After careful discussion, stereotactic radiosurgery/hypofractionated stereotactic RT may play a role for the subset of patients who are unable to tolerate the standard lengthy conventionally fractionated treatment course, for those with prior RT, or for small residual tumors. However, more studies are needed to determine the optimal approach. CONCLUSIONS: This case-based evaluation of the current literature seeks to provide examples for the management of grade 2 meningiomas and give examples of both conventional and stereotactic RT.

CyberKnife stereotactic radiosurgery for extramedullary plasmacytoma in the external auditory canal: illustrative case.

BACKGROUND: Plasmacytoma, a rare plasma cell disorder, often presents as a solitary or multiple tumors within the bone marrow or soft tissues, typically associated with multiple myeloma. Extramedullary plasmacytomas (EMPs), particularly those located in the external auditory canal (EAC), are exceedingly rare and pose significant treatment challenges given their location, anatomical complexity, and high risk of recurrence. OBSERVATIONS: The authors report the case of a 72-year-old male with a history of multiple myeloma, presenting with recurrent left EAC plasmacytoma. After initial conventional radiotherapy for the lesion, a recurrence was documented in 7 years. The patient subsequently underwent stereotactic radiosurgery, which proved successful, leading to complete resolution of the lesion without any long-term adverse effects or radiation-related complications over a 45-month period. LESSONS: This case is a unique instance of utilizing stereotactic radiosurgery for recurrent EMP in the EAC, highlighting its potential as an effective approach in managing complex plasmacytomas.

Automated contouring, treatment planning, and quality assurance for VMAT craniospinal irradiation (VMAT-CSI).

Purpose: Create a comprehensive automated solution for pediatric and adult VMAT-CSI including contouring, planning, and plan check to reduce planning time and improve plan quality. Methods: Seventy-seven previously treated CSI patients (age, 2-67 years) were used for creation of an auto-contouring model to segment 25 organs at risk (OARs). The auto-contoured OARs were evaluated using the Dice Similarity Coefficient (DSC), 95% Hausdorff Distance (HD95), and a qualitative ranking by one physician and one physicist (scale: 1-acceptable, 2-minor edits, 3-major edits). The auto-planning script was developed using the Varian Eclipse Scripting API and tested with 20 patients previously treated with either low-dose VMAT-CSI (12 Gy) or high-dose VMAT-CSI (36 Gy + 18 Gy boost). Clinically relevant metrics, planning time, and blinded physician review were used to evaluate significance of differences between the auto and manual plans. Finally, the plan preparation for treatment and plan check processes were automated to improve efficiency and safety of VMAT-CSI. Results: The auto-contours achieved an average DSC of 0.71 ± 0.15, HD95 of 4.81 ± 4.68, and reviewers' ranking of 1.22 ± 0.39, indicating close to "acceptable-as-is" contours. Compared to the manual CSI plans, the auto-plans for both dose regimens achieved statistically significant reductions in body V50% and Dmean for parotids, submandibular, and thyroid glands. The variance in the dosimetric parameters decreased for the auto-plans as compared to the manual plans indicating better plan consistency. From the blinded review, the auto-plans were marked as equivalent or superior to the manual-plans 88.3% of the time. The required time for the auto-contouring and planning was consistently between 1-2 hours compared to an estimated 5-6 hours for manual contouring and planning. Conclusions: Reductions in contouring and planning time without sacrificing plan quality were obtained using the developed auto-planning process. The auto-planning scripts and documentation will be made freely available to other institutions and clinics.

Stereotactic Radiosurgery in the Management of Brain Metastases: A Case-Based Radiosurgery Society Practice Guideline.

Purpose: Brain metastases are common among adult patients with solid malignancies and are increasingly being treated with stereotactic radiosurgery (SRS). As more patients with brain metastases are becoming eligible for SRS, there is a need for practical review of patient selection and treatment considerations. Methods and Materials: Two patient cases were identified to use as the foundation for a discussion of a wide and representative range of management principles: (A) SRS alone for 5 to 15 lesions and (B) a large single metastasis to be treated with pre- or postoperative SRS. Patient selection, fractionation, prescription dose, treatment technique, and dose constraints are discussed. Literature relevant to these cases is summarized to provide a framework for treatment of similar patients. Results: Treatment of brain metastases with SRS requires many considerations including optimal patient selection, fractionation selection, and plan optimization. Conclusions: Case-based practice guidelines developed by the Radiosurgery Society provide a practical guide to the common scenarios noted above affecting patients with metastatic brain tumors.

Automating the Treatment Planning Process for Volumetric Modulated Arc Therapy Craniospinal Irradiation.

PURPOSE: The purpose of this work is to develop a method to automate the treatment planning process of craniospinal irradiation (CSI) using volumetric modulated arc therapy. METHODS AND MATERIALS: Two scripts were developed using the Eclipse Scripting Application Programming Interface to perform auto-plan preparation and optimization. Ten patients (age, 5-44 years) previously treated at our institution with low dose volumetric modulated arc therapy CSI (prescription of 12 Gy) before total body irradiation were selected to evaluate the efficacy of the proposed auto-planning process. Paired t tests compared the dosimetric indices of the auto-plans to the manually generated clinical plans. All plans were normalized to 95% of planning target volume (PTV) coverage with the prescription dose. Two physicians and one physicist were asked to evaluate the manual plans and auto-plans of each patient in a blinded retrospective review and to indicate clinical acceptability and which plans were preferred for treatment. RESULTS: Compared with the manual CSI plans, the auto plans obtained significant reductions in Dmean to the parotids, submandibular glands, larynx, thyroid, and significant reduction in the plan PTV Dmax and D0.03 cc. The standard deviation range of the dosimetric parameters was greatly reduced for auto plans (range, 0.1-1.3 Gy) relative to manual plans (range, 0.4-5.9 Gy) indicating better plan consistency. Among the 10 patients, the auto-plans were preferred over the manual plans 90% of the time by the reviewing experts. The required time for auto-planning was approximately 1 hour compared with estimated 4 or more hours for manual planning. CONCLUSIONS: Reductions in planning time without sacrifices in plan quality were obtained using the auto-planning process compared with manual planning. Variation in plan quality was also reduced. The auto-planning scripts will be made freely available to other institutions and clinics.

The 2021 ACR/Radiology Business Management Association Workforce Survey: Diversity in Radiology.

The landscape of the radiology workforce is changing, especially in the diversity of the demographics of practicing radiologists across subspecialties, practice types, and leadership positions in both academic and nonacademic settings. The 2021 ACR/Radiology Business Management Association Workforce Survey examines these facets in detail and contributes to our understanding of the current state of diversity in the radiology workforce and potential barriers to change. The results suggest opportunities and future directions for improving diversity, equity, and inclusion.

Impact of Cochlear Dose on Hearing Preservation Following Stereotactic Radiosurgery in Treatment of Vestibular Schwannomas: A Multi-Center Study.

OBJECTIVE: Stereotactic radiosurgery (SRS) is a well-established treatment for vestibular schwannomas (VS). Hearing loss remains a main morbidity of VS and its treatments, including SRS. The effects of radiation parameters of SRS on hearing remain unknown. The goal of this study is to determine the effect of tumor volume, patient demographics, pretreatment hearing status, cochlear radiation dose, total tumor radiation dose, fractionation, and other radiotherapy parameters on hearing deterioration. METHODS: Multicenter retrospective analysis of 611 patients who underwent SRS for VS from 1990-2020 and had pre- and post-treatment audiograms. RESULTS: Pure tone averages (PTAs) increased and word recognition scores (WRSs) decreased in treated ears at 12-60 months while remaining stable in untreated ears. Higher baseline PTA, higher tumor radiation dose, higher maximum cochlear dose, and usage of single fraction resulted in higher post radiation PTA; WRS was only predicted by baseline WRS and age. Higher baseline PTA, single fraction treatment, higher tumor radiation dose, and higher maximum cochlear dose resulted in a faster deterioration in PTA. Below a maximum cochlear dose of 3 Gy, there were no statistically significant changes in PTA or WRS. CONCLUSIONS: Decline of hearing at one year in VS patients after SRS is directly related to maximum cochlear dose, single versus 3-fraction treatment, total tumor radiation dose, and baseline hearing level. The maximum safe cochlear dose for hearingtbrowd preservation at one year is 3 Gy, and the use of 3 fractions instead of one fraction was better at preserving hearing.

Patterns of Progression in Patients With Newly Diagnosed Glioblastoma Treated With 5-mm Margins in a Phase 1/2 Trial of 5-Fraction Stereotactic Radiosurgery With Concurrent and Adjuvant Temozolomide.

PURPOSE: In patients with newly diagnosed glioblastoma (GBM), tumor margins of at least 20 mm are the standard of care. We sought to determine the pattern of tumor progression in patients treated with 5-fraction stereotactic radiosurgery with 5-mm margins. METHODS AND MATERIALS: Thirty adult patients with newly diagnosed GBM were treated with 5-fraction stereotactic radiosurgery in escalated doses from 25 to 40 Gy with a 5-mm total treatment margin. Progression was scored as "in-field" if the recurrent tumor was within or contiguous with the 5-mm margin, "marginal" if between 5 and 20 mm, and "distant" if entirely occurring greater than 20 mm. As geometric patterns of progression do not reflect the biologic dose received, we calculated the minimum equi-effective dose in 2 Gy (EQD2) per day at the site of tumor recurrence. Progression was "dosimetrically in-field" if covered by a minimum EQD2 per day of 48 Gy10. RESULTS: From 2010 to 2016, 27 patients had progressed. Progression was in-field in 17 (63%), marginal in 3 (11%), and distant in 7 (26%) patients. In the 3 patients with marginal progression, the minimum EQD2 to recurrent tumor were 48 Gy10, 56 Gy10 (both considered dosimetrically in-field), and 7 Gy10 (ie, dosimetrically out-of-field). Median overall survival was 12.1 months for in-field (95% confidence interval [CI], 8.9-17.6), 15.1 months (95% CI, 10.1 to not achieved) for marginal, and 21.4 months (95% CI, 11.2-33.5) for distant progression. Patients with radiation necrosis were less likely to have in-field progression (1 of 7; 14%) compared with those without radiation necrosis (16 of 20; 80%; P = .003); those with necrosis had a median overall survival of 27.2 months (95% CI, 11.2-48.3) compared with 11.7 months (95% CI, 8.9-17.6) for patients with no necrosis (P = .077). CONCLUSIONS: In patients with newly diagnosed GBM treated with a 5-mm clinical target volume margin, 3 patients (11%) had marginal progression within 5 to 20 mm; only 1 patient (4%) may have dosimetrically benefitted from conventional 20-mm margins. Radiation necrosis was associated with in-field tumor control.

Using Holistic Residency Applicant Review and Selection in Radiation Oncology to Enhance Diversity and Inclusion-An ASTRO SCAROP-ADROP-ARRO Collaboration.

Disproportionate sex, racial, and ethnic diversity remains in the radiation oncology physician workforce despite widespread awareness and longitudinal efforts to improve representation. In this collaborative review, we define the rationale and components of holistic review and how it can be best used to provide a comprehensive evaluation of applicants to residency programs in radiation oncology. We initially discuss the current state of diversity in the field of radiation oncology and highlight the components of the residency selection process that may serve to perpetuate existing biases. Subsequently, the Accreditation Council for Graduate Medical Education and Association of American Medical Colleges holistic review framework is reviewed in detail to demonstrate the balanced assessment of potential applicants. The implementation of holistic review in medical school and residency selection to date is examined to underscore the potential value of holistic review in the radiation oncology residency selection process. Finally, recommendations for the practical implementation of holistic review in radiation oncology trainee selection are outlined.

Stereotactic radiosurgery for trigeminal neuralgia secondary to tumor: a single-institution retrospective series.

OBJECTIVE: Trigeminal neuralgia (TN) secondary to tumor represents a rare and diverse entity, and treatment for secondary TN remains controversial. This report reviews a single institution's experience in treating secondary TN with stereotactic radiosurgery (SRS) and focuses on the durability of pain relief with respect to various treatment targets, i.e., the trigeminal nerve, offending tumor, or both. METHODS: Between the years 2009 and 2021, 21 patients with TN secondary to benign (n = 13) or malignant (n = 8) tumors underwent SRS. Barrow Neurological Institute (BNI) pain intensity scale scores were collected from patient electronic medical records at baseline, initial follow-up, and 1 and 3 years post-SRS. The interval change in BNI scale score (ΔBNI) at the various follow-up time points was also calculated to assess the durability of pain relief following SRS. RESULTS: The median follow-up period was 24 (range 0.5-155) months. Five patients (24%) received treatment to the trigeminal nerve only, 10 (48%) received treatment to the tumor only, and 6 (29%) had treatment to both the nerve and tumor. The overall radiation dosage ranged from 14 to 60 Gy delivered in 1-5 fractions, with a median overall dose of 26 Gy. The median dose to the tumor was 22.5 (range 14-35) Gy, delivered in 1-5 fractions. Of the treatments targeting the tumor, 25% were delivered in a single fraction with doses ranging from 14 to 20 Gy, 60% were delivered in 3 fractions with doses ranging from 18 to 27 Gy, and 15% were delivered in 5 fractions with doses ranging from 25 to 35 Gy. The most common dose regimen for tumor treatment was 24 Gy in 3 fractions. The median biologically effective dose (with an assumed alpha/beta ratio of 10 [BED10]) for tumor treatments was 43.1 (range 13.3-60.0) Gy. There was a significant difference in the proportion of patients with recurrent pain (ΔBNI score ≥ 0) at the time of last follow-up across the differing SRS treatment targets: trigeminal nerve only, tumor only, or both (p = 0.04). At the time of last follow-up, the median ΔBNI score after SRS to the nerve only was -1, 0 after SRS to tumor only, and -2 after SRS to both targets. CONCLUSIONS: SRS offers clinical symptomatic benefit to patients with TN secondary to tumor. For optimal pain relief and response durability, treatment targeting both the tumor and the trigeminal nerve appears to be most advantageous.

Stereotactic radiosurgery for recurrent pediatric brain tumors: clinical outcomes and toxicity.

OBJECTIVE: Recurrence of brain tumors in children after the initial course of treatment remains a problem. This study evaluated the efficacy and safety of reirradiation using stereotactic radiosurgery (SRS) in patients with recurrent pediatric primary brain tumors. METHODS: This IRB-approved retrospective review included pediatric patients with recurrent primary brain tumors treated at Stanford University from 2000 to 2019 using frameless SRS. Time to local failure (LF) and distant intracranial failure (DIF) were measured from the date of SRS and analyzed using competing risk analysis. Overall survival (OS) and progression-free survival (PFS) were analyzed with the Kaplan-Meier method. RESULTS: In total, 37 patients aged 2-24 years (median age 11 years at recurrence) were treated for 48 intracranial tumors. Ependymoma (38%) and medulloblastoma (22%) were the most common tumor types. The median (range) single fraction equivalent dose of SRS was 16.4 (12-24) Gy. The median (range) follow-up time was 22.9 (1.5-190) months. The median OS of all patients was 36.8 months. Eight of 40 (20%) lesions with follow-up imaging locally recurred. The 2-year cumulative incidence of LF after reirradiation with SRS was 12.8% (95% CI 4.6%-25.4%). The 2-year cumulative incidence of DIF was 25.3% (95% CI 12.9%-39.8%). The median PFS was 18 months (95% CI 8.9-44). Five (10.4%) patients developed toxicities potentially attributed to SRS, including cognitive effects and necrosis. CONCLUSIONS: Reirradiation using SRS for recurrent pediatric brain tumors appears safe with good local control. Innovations that improve overall disease control should continue because survival outcomes after relapse remain poor.

Phase I/II Dose-Escalation Trial of 3-Fraction Stereotactic Radiosurgery for Resection Cavities From Large Brain Metastases: Health-related Quality of Life Outcomes.

OBJECTIVES: We investigated differences in quality of life (QoL) in patients enrolled on a phase I/II dose-escalation study of 3-fraction resection cavity stereotactic radiosurgery (SRS) for large brain metastases. METHODS: Eligible patients had 1 to 4 brain metastases, one of which was a resection cavity 4.2 to 33.5 cm3. European Organization for Research and Treatment of Cancer (EORTC) quality of life questionnaires core-30 (QLQ-30) and brain cancer specific module (QLQ-BN20) were obtained before SRS and at each follow-up. Nine scales were analyzed (global health status; physical, social, and emotional functioning; motor dysfunction, communication deficit, fatigue, insomnia, and future uncertainty). QoL was assessed with mixed effects models. Differences ≥10 points with q-value (adjusted P-value to account for multiplicity of testing) <0.10 were considered significant. RESULTS: Between 2009 and 2014, 50 enrolled patients completed 277 QoL questionnaires. Median questionnaire follow-up was 11.8 months. After SRS, insomnia demonstrated significant improvement (q=0.032, -17.7 points at 15 mo post-SRS), and future uncertainty demonstrated significant worsening (q=0.018, +9.9 points at 15 mo post-SRS). Following intracranial progression and salvage SRS, there were no significant QoL changes. The impact of salvage whole brain radiotherapy could not be assessed because of limited data (n=4 patients). In the 28% of patients that had adverse radiation effect, QoL had significant worsening in 3 metrics (physical functioning, q=0.024, emotional functioning q=0.001, and future uncertainty, q=0.004). CONCLUSIONS: For patients treated with 3-fraction SRS for large brain metastasis cavities, 8 of 9 QoL metrics were unchanged or improved after initial SRS. Intracranial tumor progression and salvage SRS did not impact QoL. Adverse radiation effect may be associated with at least short-term QoL impairments, but requires further investigation.

A Pilot Study of Low-Dose Craniospinal Irradiation in Patients With Newly Diagnosed Average-Risk Medulloblastoma.

PURPOSE: Medulloblastoma is one of the most common malignant brain tumors in children. To date, the treatment of average-risk (non-metastatic, completely resected) medulloblastoma includes craniospinal radiation therapy and adjuvant chemotherapy. Modern treatment modalities and now risk stratification of subgroups have extended the survival of these patients, exposing the long-term morbidities associated with radiation therapy. Prior to advances in molecular subgrouping, we sought to reduce the late effects of radiation in patients with average-risk medulloblastoma. METHODS: We performed a single-arm, multi-institution study, reducing the dose of craniospinal irradiation by 25% to 18 Gray (Gy) with the goal of maintaining the therapeutic efficacy as described in CCG 9892 with maintenance chemotherapy. RESULTS: Twenty-eight (28) patients aged 3-30 years were enrolled across three institutions between April 2001 and December 2010. Median age at enrollment was 9 years with a median follow-up time of 11.7 years. The 3-year relapse-free (RFS) and overall survival (OS) were 79% (95% confidence interval [CI] 58% to 90%) and 93% (95% CI 74% to 98%), respectively. The 5-year RFS and OS were 71% (95% CI 50% to 85%) and 86% (95% CI 66% to 94%), respectively. Toxicities were similar to those seen in other studies; there were no grade 5 toxicities. CONCLUSIONS: Given the known neurocognitive adverse effects associated with cranial radiation therapy, studies to evaluate the feasibility of dose reduction are needed. In this study, we demonstrate that select patients with average-risk medulloblastoma may benefit from a reduced craniospinal radiation dose of 18 Gy without impacting relapse-free or overall survival. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00031590.

Tumor Control Following Stereotactic Radiosurgery in Patients with Vestibular Schwannomas - A Retrospective Cohort Study.

BACKGROUND: To better counsel vestibular schwannoma patients, it is necessary to understand the tumor control rates of stereotactic radiosurgery (SRS). OBJECTIVES: To determine tumor control rates, factors determining control and complication rates following SRS. METHODS: Tertiary hospital retrospective cohort. RESULTS: 579 tumors (576 patients) were treated with SRS. 477 tumors (474 patients, 82%) had ≥1 year follow up and 60% (344) ≥3 years follow up. 88% of tumors had primary SRS and 6.7% salvage SRS. Median follow up time was 4.6 years. At 3 years, the tumor control rate of primary SRS was 89% (258 of 290) in sporadic tumors compared to 43% in Neurofibromatosis type II (3 of 17) (p < 0.01). Our bivariable survival data analysis showed that Neurofibromatosis type II, documented pre-SRS growth, tumor measured by maximum dimension, SRS given as nonprimary treatment increased hazard of failure to control. There was one case of malignancy and another of rapid change following intra-tumoral hemorrhage. For tumors undergoing surgical salvage (25 of 59), 56% had a total or near-total resection, 16% had postoperative CSF leak, with 12% new facial paralysis (House-Brackmann grade VI) and worsening of facial nerve outcomes (House-Brackmann grade worse in 59% at 12 mo). CONCLUSIONS: Control of vestibular schwannoma after primary SRS occurs in the large majority. Salvage surgical treatment was notable for higher rates of postoperative complications compared to primary surgery reported in the literature.