Vestibular Schwannoma International Study of Active Surveillance Versus Stereotactic Radiosurgery: the VISAS Study

BACKGROUND

The present study assesses the safety and efficacy of stereotactic radiosurgery (SRS) versus observation for Koos grade I and II vestibular schwannoma (VS), benign tumors affecting hearing and neurological function.

METHODS

This multicenter study analyzed data from Koos grade I and II VS patients managed with SRS (SRS group) or observation (observation group). Propensity score matching balanced patient demographics, tumor volume, and audiometry. Outcomes measured were tumor control, serviceable hearing preservation (SHP), and neurological outcomes.

RESULTS

In 125 matched patients in each group with a 36-month median follow-up (p=0.49), SRS yielded superior 5- and 10-year tumor control rates (99%, CI: 97.1%-100%, and 91.9%, CI: 79.4%-100%) vs. observation (45.8%, CI: 36.8%-57.2%, and 22%, CI: 13.2%-36.7%; p<0.001). SHP rates at 5 and 9 years were comparable (SRS 60.4%, CI: 49.9%-73%, vs. observation 51.4%, CI: 41.3%-63.9%, and SRS 27%, CI: 14.5%-50.5%, vs. observation 30%, CI: 17.2%-52.2%; p=0.53). SRS were associated with lower odds of tinnitus (OR=0.39, p=0.01), vestibular dysfunction (OR=0.11, p=0.004), and any cranial nerve palsy (OR=0.36, p=0.003), with no change in cranial nerves V or VII (p>0.05). Composite endpoints of tumor progression and/or any of the previous outcomes showed significant lower odds associated with SRS compared to observation alone (p < 0.001).

CONCLUSION

SRS management in matched cohorts of Koos grade I and II VS patients demonstrated superior tumor control, comparable hearing preservation rates, and significantly lower odds of experiencing neurological deficits. These findings delineate the safety and efficacy of SRS in in the management of this patient population.

Hypofractionated Stereotactic Radiosurgery in the Management of Brain Metastases

Stereotactic radiosurgery (SRS) is an important weapon in the management of brain metastases. Single-fraction SRS is associated with local control rates ranging from approximately 70% to 100%, which are largely dependent on lesion and postoperative cavity size. The rates of local control and improved neurocognitive outcomes compared with conventional whole-brain radiation therapy have led to increased adoption of SRS in these settings. However, when treating larger targets and/or targets located in eloquent locations, the risk of normal tissue toxicity and adverse radiation effects within healthy brain tissue becomes significantly higher. Thus, hypofractionated SRS has become a widely adopted approach, which allows for the delivery of ablative doses of radiation while also minimizing the risk of toxicity. This approach has been studied in multiple retrospective reports in both the postoperative and intact settings. While there are no reported randomized data to date, there are trials underway evaluating this paradigm. In this article, we review the role of hypofractionated SRS in the management of brain metastases and emerging data that will serve to validate this treatment approach. Pertinent articles and references were obtained from a comprehensive search of PubMed/MEDLINE and clinicaltrials.gov.

Pre-operative vs. post-operative stereotactic radiosurgery for operative metastatic brain tumors: study protocol for a phase III clinical trial

BACKGROUND AND OBJECTIVES

Almost one third of cancer patients in the United States will develop brain metastases on an annual basis. Surgical resection is indicated in the setting of brain metastases for reasons, such as maximizing local control in select patients, decompression of mass effect, and/or tissue diagnosis. The current standard of care following resection of a brain metastasis has shifted from whole brain radiation therapy to post-operative stereotactic radiosurgery (SRS). However, there is a significant rate of local recurrence within one year of postoperative SRS. Emerging retrospective and prospective data suggest pre-operative SRS is a safe and potentially effective treatment paradigm for surgical brain metastases. This trial intends to determine, for patients with an indication for resection of a brain metastasis, whether there is an increase in the time to a composite endpoint of adverse outcomes; including the first occurrence of either: local recurrence, leptomeningeal disease, or symptomatic radiation brain necrosis - in patients who receive pre-operative SRS as compared to patients who receive post-operative SRS.

METHODS

This randomized phase III clinical trial compares pre-operative with post-operative SRS for brain metastases. A dynamic random allocation procedure will allocate an equal number of patients to each arm: pre-operative SRS followed by surgery or surgery followed by post-operative SRS.

EXPECTED OUTCOMES

If pre-operative SRS improves outcomes relative to post-operative SRS, this will establish pre-operative SRS as superior. If post-operative SRS proves superior to pre-operative SRS, it will remain a standard of care and halt the increasing utilization of pre-operative SRS. If there is no difference in pre- versus post-operative SRS, then pre-operative SRS may still be preferred, given patient convenience and the potential for a condensed timeline.

DISCUSSION

Emerging retrospective and prospective data have demonstrated some benefits of pre-op SRS vs. post-op SRS. This study will show whether there is an increase in the time to the composite endpoint. Additionally, the study will compare overall survival; patient-reported outcomes; morbidity; completion of planned therapies; time to systemic therapy; time to regional progression; time to CNS progression; time to subsequent treatment; rate of radiation necrosis; rate of local recurrence; and rate of leptomeningeal disease.

TRIAL REGISTRATION NUMBER

NCT03750227 (Registration date: 21/11/2018).

Estimating the risk of brain metastasis for patients newly diagnosed with cancer

BACKGROUND

Brain metastases (BM) affect clinical management and prognosis but limited resources exist to estimate BM risk in newly diagnosed cancer patients. Additionally, guidelines for brain MRI screening are limited. We aimed to develop and validate models to predict risk of BM at diagnosis for the most common cancer types that spread to the brain.

METHODS

Breast cancer, melanoma, kidney cancer, colorectal cancer (CRC), small cell lung cancer (SCLC), and non-small cell lung cancer (NSCLC) data were extracted from the National Cancer Database to evaluate for the variables associated with the presence of BM at diagnosis. Multivariable logistic regression (LR) models were developed and performance was evaluated with Area Under the Receiver Operating Characteristic Curve (AUC) and random-split training and testing datasets. Nomograms and a Webtool were created for each cancer type.

RESULTS

We identify 4,828,305 patients from 2010-2018 (2,095,339 breast cancer, 472,611 melanoma, 407,627 kidney cancer, 627,090 CRC, 164,864 SCLC, and 1,060,774 NSCLC). The proportion of patients with BM at diagnosis is 0.3%, 1.5%, 1.3%, 0.3%, 16.0%, and 10.3% for breast cancer, melanoma, kidney cancer, CRC, SCLC, and NSCLC, respectively. The average AUC over 100 random splitting for the LR models is 0.9534 for breast cancer, 0.9420 for melanoma, 0.8785 for CRC, 0.9054 for kidney cancer, 0.7759 for NSCLC, and 0.6180 for SCLC.

CONCLUSIONS

We develop accurate models that predict the BM risk at diagnosis for multiple cancer types. The nomograms and Webtool may aid clinicians in considering brain MRI at the time of initial cancer diagnosis.

Evaluating an Academic Radiation Oncology Position

What are the factors that physicians could consider in an academic radiation oncology practice job offer? In this minireview, we discuss how prospective academic faculty could evaluate the "big 3" domains: (1) the compensation, including the direct and indirect payments; (2) the daily job, including aspects of the clinic, research, and education; and (3) the location, including geography, atmosphere, environment, and culture. If a prospective academic radiation oncologist believes that the academic practice is "great" in at least 2 of the 3 and "good" in the remaining 1, then they should likely sign the contract.

Facial Nerve Schwannoma Treatment with Stereotactic Radiosurgery (SRS) versus Resection followed by SRS: Outcomes and a Management Protocol

Background  Stereotactic radiosurgery (SRS) and resection are treatment options for patients with facial nerve schwannomas without mass effect. Objective  This article evaluates outcomes of patients treated with SRS versus resection + SRS. Method  We retrospectively compared 43 patients treated with SRS to 12 patients treated with resection + SRS. The primary study outcome was unfavorable combined endpoint, defined as worsening or new clinical symptoms, and/or tumor radiological progression. SRS (38.81 ± 5.3) and resection + SRS (67.14 ± 11.8) groups had similar clinical follow-ups. Results  At the time of SRS, the tumor volumes of SRS (mean ± standard error; 1.83 ± 0.35 mL) and resection + SRS (2.51 ± 0.75 mL) groups were similar. SRS (12.15 ± 0.08 Gy) and resection + SRS (12.16 ± 0.14 Gy) groups received similar radiation doses. SRS group (42/43, 98%) had better local tumor control than the resection + SRS group (10/12, 83%, p  = 0.04). Most of SRS (32/43, 74%) and resection + SRS (10/12, 83%) group patients reached a favorable combined endpoint following SRS ( p  = 0.52). Considering surgical associated side effects, only 2/10 patients of the resection + SRS group reached a favorable endpoint ( p  < 0.001). Patients of SRS group, who are > 34 years old ( p  = 0.02), have larger tumors (> 4 mL, 0.04), internal auditory canal (IAC) segment tumor involvement ( p  = 0.01) were more likely to reach an unfavorable endpoint. Resection + SRS group patients did not show such a difference. Conclusion  While resection is still needed for larger tumors, SRS offers better clinical and radiological outcomes compared to resection followed by SRS for facial schwannomas. Younger age, smaller tumors, and non-IAC situated tumors are factors that portend a favorable outcome.

Clinical Outcomes After Stereotactic Body Radiation Therapy for Nonspinal Bone Metastases: A Systematic Review and Meta-analysis

There are limited data available on clinical outcomes after stereotactic body radiation therapy (SBRT) for nonspinal bone metastases. We performed a systematic review and meta-analysis to characterize local control (LC), overall survival (OS), pain response rates, and toxicity after SBRT. The primary outcomes were 1-year LC, incidence of acute and late grade 3 to 5 toxicities, and overall pain response rate at 3 months. The secondary outcome was 1-year OS. The Newcastle-Ottawa scale was used for assessment of study bias, with a median score of 5 for included studies (range, 4-8). Weighted random-effects meta-analyses were conducted to estimate effect sizes. We identified 528 patients with 597 nonspinal bone lesions in 9 studies (1 prospective study and 8 retrospective observational studies) treated with SBRT. The estimated 1-year LC rate was 94.6% (95% CI, 87.0%-99.0%). The estimated 3-month combined partial and complete pain response rate after SBRT was 87.7% (95% CI, 55.1%-100.0%). The estimated combined acute and late grade 3 to 5 toxicity rate was 0.5% (95% CI, 0%-5.0%), with an estimated pathologic fracture rate of 3.1% (95% CI, 0.2%-9.1%). The estimated 1-year OS rate was 71.0% (95% CI, 51.7%-87.0%). SBRT results in excellent LC and palliation of symptoms with minimal related toxicity. Prospective investigations are warranted to further characterize long-term outcomes of SBRT for patients with nonspinal bone metastases.

Extent of Surgical Resection as a Predictor of Tumor Progression in Skull Base Chordomas: A Multicenter Volumetric Analysis

INTRODUCTION

Skull-base chordomas are aggressive tumors with a propensity for recurrence/progression. Even with standard of care (SoC), 5-year recurrence rates are variable (19%-54%). This high recurrence/progression rate correlates with increased morbidity and mortality. We sought to analyze a multicenter cohort of skull base chordomas to identify predictors of progression in patients receiving SoC.

METHODS

The [Blinded]-Neurosurgery data registry was queried for skull base chordomas treated from 2008-2020. Patients with the histopathologic diagnosis of chordoma were included. The cohort was composed of patients with preoperative and postoperative magnetic resonance imaging. Tumor volume and radiologic characteristics were obtained from axial T2 sequences using a Digital Imaging and Communications in Medicine viewer. Survival analysis was performed using Kaplan-Meier method, and time-to-event multivariate regression was performed to identify independent predictors of progression.

RESULTS

The cohort included 195 patients, of which 66 patients met inclusion criteria; median age was 44, and 28 (42%) were females. Fifty-four (82%) received SoC, 7 (11%) resection only, and 5 (8%) radiotherapy only. Median preoperative and postoperative tumor volumes were 11.55 cm3 (0.33-54.89) and 0.34 cm3 (0-42.52), respectively. Recurrence rate with SoC was 37%. Postoperative tumor volume (P = 0.010) correlated with progression. A postoperative volume of >4.9 cm3 (P = 0.044), ≤81.3% of tumor resection (P = 0.02), and lower-clivus location (P < 0.005) correlated with decreased time to progression.

CONCLUSIONS

Skull base chordomas can be challenging to resect. Even though maximal resection and radiotherapy improve rate of tumor progression, many of these lesions eventually recur. We have identified a postoperative tumor volume of ≥4.9 cm3 and extent of resection of ≤81.3% in this cohort as predictors of progression in patients receiving SoC.

Phase 1, Dose Escalation, Nonrandomized, Open-Label, Clinical Trial Evaluating the Safety and Preliminary Efficacy of Allogenic Adipose-Derived Mesenchymal Stem Cells for Recurrent Glioblastoma: A Clinical Trial Protocol

Background and Objectives

Despite standard of care with maximal safe resection and chemoradiation, glioblastoma is the most common and aggressive type of primary brain cancer. Surgical resection provides a window of opportunity to locally treat gliomas while the patient is recovering, and before initiating concomitant chemoradiation. To assess the safety and establish the maximum tolerated dose of adipose-derived mesenchymal stem cells (AMSCs) for the treatment of recurrent glioblastoma (GBM). Secondary objectives are to assess the toxicity profile and long-term survival outcomes of patients enrolled in the trial. Additionally, biospecimens will be collected to explore the local and systemic responses to this therapy.

Methods

We will conduct a phase 1, dose escalated, non-randomized, open label, clinical trial of GBM patients who are undergoing surgical resection for recurrence. Up to 18 patients will receive intra-cavitary application of AMSCs encapsulated in fibrin glue during surgical resection. All patients will be followed for up to 5 years for safety and survival data. Adverse events will be recorded using the CTCAE V5.0.

Expected Outcomes

This study will explore the maximum tolerated dose (MTD) of AMSCs along with the toxicity profile of this therapy in patients with recurrent GBM. Additionally, preliminary long-term survival and progression-free survival outcome analysis will be used to power further randomized studies. Lastly, CSF and blood will be obtained throughout the treatment period to investigate circulating molecular and inflammatory tumoral/stem cell markers and explore the mechanism of action of the therapeutic intervention.

Discussion

This prospective translational study will determine the initial safety and toxicity profile of local delivery of AMSCs for recurrent GBM. It will also provide additional survival metrics for future randomized trials.

Local control and survival after stereotactic radiosurgery for colorectal cancer brain metastases: an international multicenter analysis

OBJECTIVE

The goal of this study was to characterize local tumor control (LC), overall survival (OS), and safety of stereotactic radiosurgery for colorectal brain metastasis (CRBM).

METHODS

Ten international institutions participating in the International Radiosurgery Research Foundation provided data for this retrospective case series. This study included 187 patients with CRBM (281 tumors), with a median age of 62 years and 56.7% being male. Most patients (53.5%) had solitary tumors, although 10.7% had > 5 tumors. The median tumor volume was 2.7 cm3 (IQR 0.22-8.1 cm3), and the median margin dose was 20 Gy (IQR 18-22 Gy).

RESULTS

The 3-year LC and OS rates were 72% and 20%, respectively. Symptomatic adverse radiation effects occurred in 1.6% of patients. In the multivariate analysis, age > 65 years and tumor volume > 4.0 cm3 were significant predictors of tumor progression (hazard ratio [HR] 2.6, 95% CI 1.4-4.9; p = 0.003 and HR 3.4, 95% CI 1.7-6.9; p < 0.001, respectively). Better performance status (Karnofsky Performance Scale score > 80) was associated with a reduced risk of tumor progression (HR 0.38, 95% CI 0.19-0.73; p = 0.004). Patient age > 62 years (HR 1.6, 95% CI 1.1-2.3; p = 0.03) and the presence of active extracranial disease (HR 1.7, 95% CI 1.1-2.4; p = 0.009) were significantly associated with worse OS.

CONCLUSIONS

Stereotactic radiosurgery offers a high LC rate and a low rate of symptomatic adverse radiation effects for the majority of CRBMs. The OS and LC favored younger patients with high functional performance scores and inactive extracranial disease.

Carbon Ion Radiotherapy: An Evidence-Based Review and Summary Recommendations of Clinical Outcomes for Skull-Base Chordomas and Chondrosarcomas

Skull-base chordoma and chondrosarcoma are rare radioresistant tumors treated with surgical resection and/or radiotherapy. Because of the established dosimetric and biological benefits of heavy particle therapy, we performed a systematic and evidence-based review of the clinical outcomes of patients with skull-base chordoma and chondrosarcoma treated with carbon ion radiotherapy (CIRT). A literature review was performed using a MEDLINE search of all articles to date. We identified 227 studies as appropriate for review, and 24 were ultimately included. The published data illustrate that CIRT provides benchmark disease control outcomes for skull-base chordoma and chondrosarcoma, respectively, with acceptable toxicity. CIRT is an advanced treatment technique that may provide not only dosimetric benefits over conventional photon therapy but also biologic intensification to overcome mechanisms of radioresistance. Ongoing research is needed to define the magnitude of benefit, patient selection, and cost-effectiveness of CIRT compared to other forms of radiotherapy.

Prompt Pain Relief: Advanced Practice Provider Led Rapid Access Palliative Radiotherapy Clinic

PURPOSE/OBJECTIVE(S)

Patients (pts) commonly present to radiation oncology with painful bone metastases requiring urgent palliative radiotherapy (RT). Unfortunately, the pre-existing scheduling workflow for palliative referrals can be inefficient, causing significant delays before pts are seen by a radiation oncologist (RO). Our institution implemented an alternative workflow, which led to the creation of an advanced practice provider (APP) led Rapid Access Palliative RT Clinic (PRC). We investigated the impact of the PRC in reducing time from referral to consultation for pts in need of palliative RT.

MATERIALS/METHODS

In March 2022, we initiated an outpatient APP led PRC focused on the APP driving consultations supervised by the weekly on-call RO. Pts are offered a variety of options for consultation such as virtual, in clinic with reserved simulation time, and when appropriate virtual simulation, using diagnostic imaging for RT planning, and same day treatment requiring only one visit to the department. The clinic provides a point of contact that fosters multidisciplinary interaction and proactive continuity of care and follow up. Following institutional review board approval, pts who received palliative RT for painful bone metastases from June 2021 to December 2022 were retrospectively reviewed. Data was collected with respect to when the referral was placed for palliative RT and when the pts was seen for consultation by a provider. The cohort of pts seen between June 2022 and December 2022 represented the PRC cohort. A comparison cohort of pts treated between June 2021 and December 2021 represented the pre-PRC cohort. Unpaired T-test was used to analyze time from referral to consultation (TTC) between groups. P value < 0.05 was considered statistically significant.

RESULTS

During the pre-PRC period, 91 patients were treated, including 12 inpatients and 79 outpatients, while during the PRC period, 101 pts were treated, including 7 inpatients and 94 outpatients. The median dose was 8 Gy in 1 fraction for both cohorts. During the PRC period, there was a 19% increase in outpatients treated for bone metastases. Restricted to just outpatients, the average TTC was 10.4 days (SD 10.2) for pre-PRC cohort versus 6.3 days (SD 6.6) for the PRC cohort, which was statistically significant (p = 0.003). This was a 39% reduction in TTC. During the PRC period, 17 pts were not seen in the APP led PRC while 77 were seen in the PRC. The most common reason was an erroneous referral for curative intent treatment instead of palliative bone treatment. During the PRC period, those pts seen in the APP led PRC had an average TTC of 5.1 days (SD 4.6) versus 11.5 days (SD 10.64) for those not seen in the PRC (p = 0.03) with a 56% reduction in TTC.

CONCLUSION

The APP led PRC clinic significantly decreased time from referral to consultation for pts requiring urgent palliative RT for painful bone metastases. Further research is underway to determine if the PRC increases referrals, patients treated, patient satisfaction, and the impact on staffing RO.

Immune Checkpoint Inhibition and Single Fraction Stereotactic Radiosurgery in Non-Small Cell Lung Cancer Brain Metastases: An International Multicenter Study of 395 Patients

PURPOSE/OBJECTIVE(S)

Brain metastases most commonly arise from non-small cell lung cancer (NSCLC). In recent years, immune checkpoint inhibitors (ICI) have demonstrated improvements in overall survival (OS) in NSCLC. However, concerns remain about the risk of radiation necrosis (RN) when ICI are administered with stereotactic radiosurgery (SRS).

MATERIALS/METHODS

Logistic regression was used to evaluate prognostic factors associated with the development of any grade RN and symptomatic RN. Cumulative incidence of RN was evaluated using competing risks analysis and the Fine and Gray model, where the null hypothesis was rejected for p < 0.05.

RESULTS

There were 395 patients with 2,513 brain metastases treated across 11 international institutions included in the analysis. The median follow-up was 14.2 months. Median patient age was 67 years (Interquartile Range [IQR]: 61-73), 53.4% were male, the median Karnofsky Performance Status was 80 (IQR: 80-90), and 88.6% has active extracranial disease at the time of SRS. The median margin dose was 19 Gy (IQR: 18-20), 97.5% of patients were treated on the Gamma Knife ®, 3.8% underwent prior whole brain radiation therapy (WBRT). The median V12 Gy was 5.2 cm3 and 36.5% of patients had a V12 Gy ≥ 10 cm3, anti-PD-1 agents were administered in 91.6% of patients. A V12 Gy ³ 10 cm3 was associated with an increased risk of developing any grade RN; odds ratio (OR): 2.12, p = 0.04 and OR: 2.18; p = 0.03 on univariable and multivariable analysis, respectively. Similarly, a V12 Gy ≥ 10 cm3 was associated with an increased risk of developing symptomatic RN; OR: 3.80, p = 0.003 and OR: 3.95; p = 0.003 on univariable and multivariable analysis, respectively. Receipt of concurrent ICI and prior WBRT were not statistically significant. At 1-year, the cumulative incidence of any grade and symptomatic RN was 4.8% and 3.8%, respectively. The cumulative incidence of any grade RN was 3.8% vs. 5.3% for the concurrent and non-concurrent groups at 1-year, respectively (p = 0.35). The cumulative incidence of symptomatic RN was 3.8% vs. 3.6% for the concurrent and non-concurrent groups at 1-year, respectively (p = 0.95).

CONCLUSION

The risk of any grade and symptomatic RN following SRS and ICI administration for NSCLC brain metastases increases as the V12 Gy exceeds 10 cm3. Concurrent ICI and SRS does not appear to increase this risk. Radiosurgical planning techniques should aim to minimize the V12 Gy.

Selected-Lesion SRS as a Novel Strategy in Treatment of Patients with Multiple Brain Metastases

PURPOSE/OBJECTIVE(S)

With the increasing use of intracranial SRS (SRS) for treatment of patients with >10-15 brain metastases treatment; debate remains in the literature about how these patients should be treated. While many advocate for treatment of all lesions with either SRS or whole brain radiation therapy (WBRT), several groups are considering selected-lesion SRS (SL-SRS) where only a subset of intracranial lesions are treated. However, the current practice patterns of SL-SRS are not known.

MATERIALS/METHODS

A survey of 19 questions was created using open-ended and multiple-choice style questions on SL-SRS practices and indications. The survey was distributed to providers in the US and internationally who perform SRS frequently. Ten out of 50 institutions provided responses reflecting the practices of 16 providers. Descriptive statistics was used to compare answers to each question when applicable including percentages and ranges.

RESULTS

SL-SRS was performed at 8/10 institutions, (5 out of 6 US institutions and 3 out of 4 international institutions). Only 2 institutions had established clinical indications for SL-SRS (one in the US and one internationally) and one additional US institution reported clinical trials that require SL-SRS to study efficacy of CNS penetrating targeted therapies. One program reported research protocols for untreated brain metastases that would take priority over SL-SRS (program outside the US). Size of the lesion was cited as the most important factor (90%) when deciding to treat any single lesion. Next, lesion location and focal signs/symptoms were both considered moderately important. 80% ranked distance from prior SRS as the least important factor. Perilesional edema was also less important at most programs (90%). Lesion location and presence of symptoms were also considered important. There were several factors that would encourage providers to consider SL-SRS in a patient. Prior WBRT; progressing systemic disease and CNS-penetrating drug option available; and progressing systemic disease and immunotherapy option available were the most common responses. Most respondents cited "specific request by medical oncology" as well as "cooperative studies in this topic" as factors that might push them towards SL-SRS. Several institutions specified factors beyond the listed options. One institution reported that for patients with >20 lesions, they treated the largest lesions with SRS then follow with WBRT, termed the "pre-WBRT boost." Progression of untreated lesions was the most common reason why providers would bring back patients for additional treatment.

CONCLUSION

The responses to this survey demonstrate that patients with >15-20 intracranial lesions, prior WBRT, and worsening systemic disease with CNS penetrating systemic therapies available are being considered for SL-SRS.

Sensitivity of the PROMIS-10 for Capturing Radiation-Related Quality of Life Changes

PURPOSE/OBJECTIVE(S)

Patient reported outcomes (PROs) are becoming more common when assessing the effects of radiotherapy (RT). The aim of this study was to assess the sensitivity of the Mental and Physical domains of the Patient-Reported Outcomes Measurement Information System 10 (PROMIS-10) to radiotherapy and determine what predictors were associated with change in quality of life.

MATERIALS/METHODS

Patients, regardless of cancer type, were enrolled on a multi-site prospective registry. Inclusion criteria included curative radiotherapy and completion of the PROMIS-10 prior to treatment (Baseline) and at End of Treatment (EOT). To assess the strongest predictors of change in the T score of mental and physical health, we included 14 demographic characteristics and treatment variables in a multivariable stepwise regression.

RESULTS

A total of 7,586 patients were eligible for the analysis. The median age was 65 (range 18-94), 54% were males, and 94% were white. A majority received photons (62.5%) and the others received protons (37.5%) with an average dose of 52.3 Gy (range 20-80 Gy) over an average of 22.6 fractions (range 1-66). Patient disease sites were sub-grouped into 12 categories: Breast (25.5%), GU (23.0%), H&N (11.1%), CNS (8.5%), Pancreas-Biliary (6.7%), Thoracic (5.7%), Soft Tissue/Bone (5.0%), Esophagus-Gastric (4.7%), Colorectal-Anus (4.4%), Heme/Lymph (2.6%), GYN (1.8%), and Skin/Melanoma (1.0%). For both outcomes, the model selected disease group as an important predictor and it explained the most variance in the outcome compared to the rest of the predictors. When probing the effect of disease group, H&N, Esophagus-Gastric, Skin/Melanoma, and Colorectal-Anus had the largest mean decrease in quality of life for both domains. For mental health, the model also selected radiation type. Patients treated with protons indicated a bigger decrease in mental health compared to patients treated with photons (b = 0.43, 95% CI: -0.01, 0.69). For physical health, the model selected total fractions, ethnicity, and T stage. As number of fractions increased, the physical health change scores became more negative, on average (b = -0.03, 95% CI: -0.05, -0.01). Hispanic/Latino patients indicated a smaller decrease in physical health compared to White (b = -1.50, 95% CI: -2.60, -0.40) and Unknown ethnicity patients (b = -1.82, 95% CI: -3.36, -0.27). Finally, patients with a T stage of 3 or greater indicated a smaller decrease in physical health than patients with a T stage less than 3 (b = 0.76, 95% CI: 0.35, 1.16).

CONCLUSION

The PROMIS-10 did not capture significant change for patients undergoing curative radiotherapy except for patients with Head & Neck, Esophagus-Gastric, Skin, and Colorectal-Anus cancer. Further analyses should explore which patients experience the greatest change in quality of life within disease group.

Immune checkpoint inhibition and single fraction stereotactic radiosurgery in brain metastases from non-small cell lung cancer: an international multicenter study of 395 patients

PURPOSE

Approximately 80% of brain metastases originate from non-small cell lung cancer (NSCLC). Immune checkpoint inhibitors (ICI) and stereotactic radiosurgery (SRS) are frequently utilized in this setting. However, concerns remain regarding the risk of radiation necrosis (RN) when SRS and ICI are administered concurrently.

METHODS

A retrospective study was conducted through the International Radiosurgery Research Foundation. Logistic regression models and competing risks analyses were utilized to identify predictors of any grade RN and symptomatic RN (SRN).

RESULTS

The study included 395 patients with 2,540 brain metastases treated with single fraction SRS and ICI across 11 institutions in four countries with a median follow-up of 14.2 months. The median age was 67 years. The median margin SRS dose was 19 Gy; 36.5% of patients had a V12 Gy ≥ 10 cm3. On multivariable analysis, V12 Gy ≥ 10 cm3 was a significant predictor of developing any grade RN (OR: 2.18) and SRN (OR: 3.95). At 1-year, the cumulative incidence of any grade and SRN for all patients was 4.8% and 3.8%, respectively. For concurrent and non-concurrent groups, the cumulative incidence of any grade RN was 3.8% versus 5.3%, respectively (p = 0.35); and for SRN was 3.8% vs. 3.6%, respectively (p = 0.95).

CONCLUSION

The risk of any grade RN and symptomatic RN following single fraction SRS and ICI for NSCLC brain metastases increases as V12 Gy exceeds 10 cm3. Concurrent ICI and SRS do not appear to increase this risk. Radiosurgical planning techniques should aim to minimize V12 Gy.

Prompt Pain Relief from Bone Metastases: Mature Results from the Virtual Simulation Program

PURPOSE/OBJECTIVE(S)

Rapidpain relief for patients with bone metastases can be a challenge due to the lengthy and complex radiotherapy workflow. The purpose of this study was to evaluate the time (in days) between initial radiation oncology consultation and start of palliative radiation treatment after implementing an alternative virtual simulation palliative workflow.

MATERIALS/METHODS

Patients meeting strict criteria were selected for virtual simulation, which included only those with painful bone metastases who were recommended palliative radiotherapy using standard AP/PA or opposed lateral fields. A recent (within 30 days) diagnostic CT scan clearly visualizing the target volume was required for treatment planning. For comparison, a reference group of 40 consecutive patients with bone metastases that underwent in-person CT simulation prior to virtual simulation implementation was reviewed.

RESULTS

Forty-five patients were treated for painful bone metastases as part of the virtual simulation program from May 2021 to October 2022. Regarding travel distance, 23 patients lived locally (<50 miles from treatment center) and 22 patients were distant (≥50 miles from treatment center). Average time from consult to treatment for all virtual simulation patients was 3.7 days compared to 7.5 days for in-person CT simulation patients (3.8 days sooner on average, p = <0.001). For outpatient treatments, average time from consult to treatment for distant virtual simulation patients was 4.0 days compared to 8.9 days for distant in-person CT simulation patients (4.9 days sooner on average, p = 0.003).

CONCLUSION

The virtual simulation program decreased the time from consult to start of treatment for patients recommended palliative radiotherapy for painful bone metastases by over 50%. This benefit was most significant for outpatients traveling ≥ 50 miles for treatment. Virtual simulation-based planning can be considered for patients anxious to proceed with radiotherapy quickly, or in underserved settings with limited transportation options to regional treatment centers.

Preoperative stereotactic radiosurgery as neoadjuvant therapy for resectable brain tumors

PURPOSE

Stereotactic radiosurgery (SRS) is a method of delivering conformal radiation, which allows minimal radiation damage to surrounding healthy tissues. Adjuvant radiation therapy has been shown to improve local control in a variety of intracranial neoplasms, such as brain metastases, gliomas, and benign tumors (i.e., meningioma, vestibular schwannoma, etc.). For brain metastases, adjuvant SRS specifically has demonstrated positive oncologic outcomes as well as preserving cognitive function when compared to conventional whole brain radiation therapy. However, as compared with neoadjuvant SRS, larger post-operative volumes and greater target volume uncertainty may come with an increased risk of local failure and treatment-related complications, such as radiation necrosis. In addition to its role in brain metastases, neoadjuvant SRS for high grade gliomas may enable dose escalation and increase immunogenic effects and serve a purpose in benign tumors for which one cannot achieve a gross total resection (GTR). Finally, although neoadjuvant SRS has historically been delivered with photon therapy, there are high LET radiation modalities such as carbon-ion therapy which may allow radiation damage to tissue and should be further studied if done in the neoadjuvant setting. In this review we discuss the evolving role of neoadjuvant radiosurgery in the treatment for brain metastases, gliomas, and benign etiologies. We also offer perspective on the evolving role of high LET radiation such as carbon-ion therapy.

METHODS

PubMed was systemically reviewed using the search terms "neoadjuvant radiosurgery", "brain metastasis", and "glioma". ' Clinicaltrials.gov ' was also reviewed to include ongoing phase III trials.

RESULTS

This comprehensive review describes the evolving role for neoadjuvant SRS in the treatment for brain metastases, gliomas, and benign etiologies. We also discuss the potential role for high LET radiation in this setting such as carbon-ion radiotherapy.

CONCLUSION

Early clinical data is very promising for neoadjuvant SRS in the setting of brain metastases. There are three ongoing phase III trials that will be more definitive in evaluating the potential benefits. While there is less data available for neoadjuvant SRS for gliomas, there remains a potential role, particularly to enable dose escalation and increase immunogenic effects.

Local Control and Survival Outcomes After Stereotactic Radiosurgery for Brain Metastases From Gastrointestinal Primaries: An International Multicenter Analysis

BACKGROUND

There are limited data regarding outcomes for patients with gastrointestinal (GI) primaries and brain metastases treated with stereotactic radiosurgery (SRS).

OBJECTIVE

To examine clinical outcomes after SRS for patients with brain metastases from GI primaries and evaluate potential prognostic factors.

METHODS

The International Radiosurgery Research Foundation centers were queried for patients with brain metastases from GI primaries managed with SRS. Primary outcomes were local control (LC) and overall survival (OS). Kaplan-Meier analysis was used for univariate analysis (UVA) of prognostic factors. Factors significant on UVA were evaluated with a Cox multivariate analysis proportional hazards model. Logistic regressions were used to examine correlations with RN.

RESULTS

We identified 263 eligible patients with 543 brain metastases. Common primary sites were rectal (31.2%), colon (31.2%), and esophagus (25.5%) with a median age of 61.6 years (range: 37-91.4 years) and a median Karnofsky performance status (KPS) of 90% (range: 40%-100%). One-year and 2-year LC rates were 83.5% (95% CI: 78.9%-87.1%) and 73.0% (95% CI: 66.4%-78.5%), respectively. On UVA, age >65 years ( P = .001), dose <20 Gy ( P = .006) for single-fraction plans, KPS <90% ( P < .001), and planning target volume ≥2cc ( P = .007) were associated with inferior LC. All factors other than dose were significant on multivariate analysis ( P ≤ .002). One-year and 2-year OS rates were 68.0% (95% CI: 61.5%-73.6%) and 31.2% (95% CI: 24.6%-37.9%), respectively. Age > 65 years ( P = .006), KPS <90% ( P = .005), and extracranial metastases ( P = .05) were associated with inferior OS.

CONCLUSION

SRS resulted in comparable LC with common primaries. Age and KPS were associated with both LC and OS with planning target volume and extracranial metastases correlating with LC and OS, respectively. These factors should be considered in GI cancer patient selection for SRS.

Selected-Lesion Stereotactic Radiosurgery (SL-SRS) as a Novel Strategy in the Treatment of Patients With Multiple Brain Metastases

INTRODUCTION

With the diminishing use of whole-brain radiotherapy (WBRT), there is increasing debate regarding the maximum number of brain metastases that should be treated with stereotactic radiosurgery (SRS). In patients with >10-15 lesions, some groups are proposing a new approach - selected-lesion SRS (SL-SRS) - where only a subset of intracranial lesions are chosen for irradiation. This study is an initial look into this practice.

METHODS

This is a cross-sectional exploratory survey study. A survey of 19 questions was created by the International Radiosurgery Research Foundation (IRRF) using open-ended and multiple-choice style questions on SL-SRS practices and indications with the goal of qualitatively understanding how SL-SRS is being implemented worldwide. The survey was distributed to physicians in the United States (US) and internationally who are members of the IRRF and who perform SRS frequently. Ten out of 50 IRRF institutions provided responses reflecting the practices of 16 physicians.

RESULTS

SL-SRS is being performed at 8/10 institutions. The most common reasons for using SL-SRS included patients with prior WBRT, patients with progressing systemic disease with central nervous system (CNS)-penetrating or immunotherapies available, specific requests from medical oncology, and cooperative studies using this approach. Lesion size was cited as the most important factor when choosing to irradiate any single lesion. The majority of respondents reported 30 mm and 40 mm as size cutoffs (by largest dimension) for treatment of a lesion in eloquent and non-eloquent locations, respectively. Eloquence of lesion location and attributable symptoms were also considered important. Progression of untreated lesions was the most common reason reported for bringing patients back for additional treatment.

CONCLUSION

The responses to this survey show that SL-SRS is being used, allowing for small/asymptomatic brain metastases to be left safely unirradiated. It is currently used in patients who have >10-15 lesions with prior WBRT, those with progression of extracranial disease but with acceptable systemic treatment options, and those with poor functional status. The incorporation of this new approach into clinical trials should be considered for the safe study of the efficacy of new CNS-penetrating systemic therapies.

Comparison of first-line radiosurgery for small-cell and non-small cell lung cancer brain metastases (CROSS-FIRE)

INTRODUCTION

Historical reservations regarding stereotactic radiosurgery (SRS) for small-cell lung cancer (SCLC) brain metastases include concerns for short-interval and diffuse central nervous system (CNS) progression, poor prognoses, and increased neurological mortality specific to SCLC histology. We compared SRS outcomes for SCLC and non-small cell lung cancer (NSCLC) where SRS is well established.

METHODS

Multicenter first-line SRS outcomes for SCLC and NSCLC from 2000 to 2022 were retrospectively collected (n = 892 SCLC, n = 4785 NSCLC). Data from the prospective Japanese Leksell Gamma Knife Society (JLGK0901) clinical trial of first-line SRS were analyzed as a comparison cohort (n = 98 SCLC, n = 814 NSCLC). Overall survival (OS) and CNS progression were analyzed using Cox proportional hazard and Fine-Gray models, respectively, with multivariable adjustment for cofactors including age, sex, performance status, year, extracranial disease status, and brain metastasis number and volume. Mutation-stratified analyses were performed in propensity score-matched retrospective cohorts of epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) positive NSCLC, mutation-negative NSCLC, and SCLC.

RESULTS

OS was superior for patients with NSCLC compared to SCLC in the retrospective dataset (median OS = 10.5 vs 8.6 months; P < .001) and in the JLGK0901 dataset. Hazard estimates for first CNS progression favoring NSCLC were similar in both datasets but reached statistical significance in the retrospective dataset only (multivariable hazard ratio = 0.82, 95% confidence interval = 0.73 to 0.92, P = .001). In the propensity score-matched cohorts, there were continued OS advantages for NSCLC patients (median OS = 23.7 [EGFR and ALK positive NSCLC] vs 13.6 [mutation-negative NSCLC] vs 10.4 months [SCLC], pairwise P values < 0.001), but no statistically significant differences in CNS progression were observed in the matched cohorts. Neurological mortality and number of lesions at CNS progression were similar for NSCLC and SCLC patients. Leptomeningeal progression was increased in patients with NSCLC compared to SCLC in the retrospective dataset only (multivariable hazard ratio = 1.61, 95% confidence interval = 1.14 to 2.26, P = .007).

CONCLUSIONS

After SRS, SCLC histology was associated with shorter OS compared to NSCLC. CNS progression occurred earlier in SCLC patients overall but was similar in patients matched on baseline factors. SCLC was not associated with increased neurological mortality, number of lesions at CNS progression, or leptomeningeal progression compared to NSCLC. These findings may better inform clinical expectations and individualized decision making regarding SRS for SCLC patients.

The incorporation of cognitive-sparing techniques into prophylactic cranial irradiation in the management of small cell lung cancer

The use of prophylactic cranial irradiation (PCI) remains an important component in the management of small cell lung cancer (SCLC). This is due to the high rates of subclinical brain metastases at the time of diagnosis. Following a response to initial treatment, PCI historically has been associated with improvements in overall survival and decreased development of brain metastases in patients with limited stage (LS-SCLC) and extensive stage (ES-SCLC) SCLC. However, PCI is commonly withheld in these settings in favor of observation, largely due to its association with cognitive sequelae following treatment. While randomized data has demonstrated that in patients with ES-SCLC, PCI may be withheld in favor of close MRI surveillance without a detriment in overall survival or cognitive functioning, these patients did not undergo formal neuropsychological assessments. In recent years, cognitive sparing techniques incorporated into whole brain radiation therapy and PCI, such as the addition of memantine and hippocampal avoidance, have demonstrated significant improvements in cognitive outcomes. As the overall survival in patients with SCLC continues to improve due to the incorporation of novel systemic therapies (e.g., immune checkpoint inhibitors), the role of PCI and maximizing quality of life remains a highly relevant topic. This article reviews the role of PCI and cognitive-sparing techniques in the management of SCLC.

National Cancer Institute Collaborative Workshop on Shaping the Landscape of Brain Metastases Research: challenges and recommended priorities

Brain metastases are an increasing global public health concern, even as survival rates improve for patients with metastatic disease. Both metastases and the sequelae of their treatment are key determinants of the inter-related priorities of patient survival, function, and quality of life, mandating a multidimensional approach to clinical care and research. At a virtual National Cancer Institute Workshop in September, 2022, key stakeholders convened to define research priorities to address the crucial areas of unmet need for patients with brain metastases to achieve meaningful advances in patient outcomes. This Policy Review outlines existing knowledge gaps, collaborative opportunities, and specific recommendations regarding consensus priorities and future directions in brain metastases research. Achieving major advances in research will require enhanced coordination between the ongoing efforts of individual organisations and consortia. Importantly, the continual and active engagement of patients and patient advocates will be necessary to ensure that the directionality of all efforts reflects what is most meaningful in the context of patient care.

Unknown Causes of Death in Cancer Patients

OBJECTIVES

Deaths from an unknown cause are difficult to adjudicate and oncologic studies of comparative effectiveness often demonstrate inconsistencies in incorporating these deaths and competing events (eg, heart disease and stroke) in their analyses. In this study, we identify cancer patients most at risk for death of an unknown cause.

METHODS

This retrospective, population-based study used cancer registry data from the Surveillance, Epidemiology, and End Results database (1992-2015). The absolute rate of unknown causes of death (COD) cases stratified by sex, marital status, race, treatment, and cancer site were calculated and a multivariable logistic regression model was applied to obtain adjusted odds ratios with 95% CIs.

RESULTS

Out of 7,154,779 cancer patients across 22 cancer subtypes extracted from Surveillance, Epidemiology, and End Results, 3,448,927 died during follow-up and 276,068 (7.4%) of these deaths were from unknown causes. Patients with an unknown COD had a shorter mean survival time compared with patients with known COD (36.3 vs 65.7 mo, P < 0.001). The contribution of unknown COD to total mortality was highest in patients with more indolent cancers (eg, prostate [12.7%], thyroid [12.3%], breast [10.7%]) and longer follow-up (eg, >5 to 10 y). One, 3, and 5-year cancer-specific survival (CSS) calculations including unknown COD were significantly decreased compared with CSS estimates excluding cancer patients with unknown COD.

CONCLUSION

Of the patients, 7.4% died of unknown causes during follow-up and the proportion of death was higher with longer follow-up and among more indolent cancers. The attribution of high percentages of unknown COD to cancer or non-cancer causes could impact population-based cancer registry studies or clinical trial outcomes with respect to measures involving CSS and mortality.

Development and validation of a recursive partitioning analysis-based pretreatment decision-making tool identifying ideal candidates for spine stereotactic body radiation therapy

BACKGROUND

This study was aimed at developing and validating a decision-making tool predictive of overall survival (OS) for patients receiving stereotactic body radiation therapy (SBRT) for spinal metastases.

METHODS

Three hundred sixty-one patients at one institution were used for the training set, and 182 at a second institution were used for external validation. Treatments most commonly involved one or three fractions of spine SBRT. Exclusion criteria included proton therapy and benign histologies.

RESULTS

The final model consisted of the following variables and scores: Spinal Instability Neoplastic Score (SINS) ≥ 6 (1), time from primary diagnosis < 21 months (1), Eastern Cooperative Oncology Group (ECOG) performance status = 1 (1) or ECOG performance status > 1 (2), and >1 organ system involved (1). Each variable was an independent predictor of OS (p < .001), and each 1-point increase in the score was associated with a hazard ratio of 2.01 (95% confidence interval [CI], 1.79-2.25; p < .0001). The concordance value was 0.75 (95% CI, 0.71-0.78). The scores were discretized into three groups-favorable (score = 0-1), intermediate (score = 2), and poor survival (score = 3-5)-with 2-year OS rates of 84% (95% CI, 79%-90%), 46% (95% CI, 36%-59%), and 21% (95% CI, 14%-32%), respectively (p < .0001 for each). In the external validation set (182 patients), the score was also predictive of OS (p < .0001). Increasing SINS<zaq;6> was predictive of decreased OS as a continuous variable (p < .0001).

CONCLUSIONS

This novel score is proposed as a decision-making tool to help to optimize patient selection for spine SBRT. SINS may be an independent predictor of OS.

The Role of Stereotactic Radiosurgery for Functioning and Nonfunctioning Pituitary Adenomas

Pituitary adenomas are benign brain tumors that comprise 10%-20% of all central nervous system neoplasms. In recent years, stereotactic radiosurgery (SRS) has emerged as a highly effective treatment option in the management of functioning and nonfunctioning adenomas. It is associated with tumor control rates frequently ranging from 80% to 90% in published reports. While permanent morbidity is uncommon, potential side effects include endocrine dysfunction, visual field deficits, and cranial nerve neuropathies. In patients where single fraction SRS would pose an unacceptable risk (e.g. large lesion size or close proximity to the optic apparatus), hypofractionated SRS delivered in 1-5 fractions is a potential treatment option; however, available data are limited. A comprehensive literature search of PubMed/MEDLINE, CINAHL, Embase, and the Cochrane Library was conducted to identify articles reporting on the use of SRS in functioning and nonfunctioning pituitary adenomas.

Stereotactic Radiosurgery for Intraventricular Metastases: A Multicenter Study

BACKGROUND

Intraventricular metastases (IVMs) are uncommon, and their optimal management remains debatable.

OBJECTIVE

To define the safety and efficacy of stereotactic radiosurgery (SRS) in the treatment of IVMs.

METHODS

This retrospective, multicenter study included patients managed with SRS for IVMs. SRS-induced adverse events, local tumor or intracranial progression, and the frequency of new-onset hydrocephalus or leptomeningeal spread were documented. Analyses of variables related to patient neuroimaging or clinical outcomes were also performed.

RESULTS

The cohort included 160 patients from 11 centers who underwent SRS for treatment of 1045 intracranial metastases, of which 196 were IVMs. The median survival from SRS was 10 months. Of the 154 patients and 190 IVMs with imaging follow-up, 94 patients (61%) experienced distant intracranial disease progression and 16 IVMs (8.4%) progressed locally. The 12- and 24-month local IVM control rates were 91.4% and 86.1%, respectively. Sixteen (10%) and 27 (17.5%) patients developed hydrocephalus and leptomeningeal dissemination post-SRS, respectively. Adverse radiation effects were documented in 24 patients (15%). Eleven patients (6.9%) died because of intracranial disease progression.

CONCLUSION

SRS is an effective treatment option for IVMs, with a local IVM control rate comparable with SRS for parenchymal brain metastases. Leptomeningeal spread and hydrocephalus in patients with IVM occur in a minority of patients, but these patients warrant careful follow-up to detect these changes.

Contemporary radiotherapy and radiosurgery techniques for refractory pituitary adenomas

The pituitary gland is a potential site for a range of pathologies, for which treatment can involve resection and/or ionizing radiation. Modern stereotactic radiosurgery (SRS) involves highly conformal radiation, allowing for the delivery of high doses to the tumor while simultaneously sparing nearby healthy structures. SRS has become a standard treatment option for residual or recurrent pituitary adenomas. It has been used for both functioning and nonfunctioning pituitary adenomas, with reported local tumor control over 90% and moderate rates of endocrine remission in functioning adenomas. We aim to briefly review the existing indictions and supporting literature for the use of SRS for refractory adenomas.

Exposure to radon and heavy particulate pollution and incidence of brain tumors

BACKGROUND

Global incidence for brain tumors varies substantially without explanation. Studies correlating radon exposure and incidence are inconclusive. Particulate pollution has been linked to increased tumor incidence. Particulates may disrupt the blood-brain barrier allowing intracranial exposure to oncogenic radon. We investigated the relationship between exposure to residential radon, particulate pollution, and brain tumor incidence in the United States (US).

METHODS

County-level median radon testing results and annual air quality index values were obtained and divided into tertiles. Counties without both values were excluded. Four groups of counties were generated: high particulate/high radon (high/high), high/low, low/high, and low/low. Using incidence data from the Central Brain Tumor Registry of the US (provided by CDC's National Program of Cancer Registries and NCI's SEER), annual age-adjusted incidence rates (AAAIRs) by group were generated by behavior. Incidence rate ratios were calculated to examine for significant differences (α = .05). Poisson regression accounting for possible confounders was conducted.

RESULTS

Counties with available data included 83% of the US population. High/high exposure was significantly associated with increased AAAIR of all non-malignant tumors (up to 26% higher, including most meningiomas) even after accounting for potential confounders. An increased AAAIR was noted for all malignant tumors (up to 10% higher), including glioblastoma, but was negated after accounting for demographic/socioeconomic differences.

CONCLUSIONS

We present the first report suggesting increased non-malignant brain tumor incidence in regions with high particulate and radon exposure. These findings provide insight into unexplained variation in tumor incidence. Future studies are needed to validate these findings in other populations.

Current advances in the surgical treatment of glossopharyngeal neuralgia

Glossopharyngeal neuralgia (GPN) is a neurological condition characterized by paroxysmal, stabbing-like pain along the distribution of the glossopharyngeal nerve that lasts from a couple of seconds to minutes. Pharmacological treatment with anticonvulsants is the first line of treatment; however, about 25% of patients remain symptomatic and require surgical intervention, which is usually done via microvascular decompression (MVD) with or without rhizotomy. More recently, the use of stereotactic radiosurgery (SRS) has been utilized as an alternative treatment method to relieve patient symptoms by causing nerve ablation. We conducted a systematic review to analyze whether MVD without rhizotomy is an equally effective treatment for GPN as MVD with the use of concurrent rhizotomy. Moreover, we sought to explore if SRS, a minimally invasive alternative surgical option, achieves comparable outcomes. We included retrospective studies and case reports in our search. We consulted PubMed and Medline, including articles from the year 2000 onwards. A total of 36 articles were included for review. Of all included patients with glossopharyngeal neuralgia, the most common offending artery compressing the glossopharyngeal nerve was the posterior inferior cerebellar artery (PICA). MVD alone was successful achieving pain relief immediately postoperatively in about 85% of patients, and also long term in 65-90% of patients. The most common complication found on MVD surgery was found to be transient hoarseness and transient dysphagia. Rhizotomy alone shows an instant pain relief in 85-100% of the patients, but rate of long-term pain relief was lower compared to MVD. The most common adverse effects observed after a rhizotomy were dysphagia and dysesthesia along the distribution of the glossopharyngeal nerve. SRS had promising results in pain reduction when using 75 Gy radiation or higher; however, long-term rates of pain relief were lower. MVD, rhizotomy, and SRS are effective methods to treat GPN as they help achieve instant pain relief and the decrease use of medication. Patients with MVD alone presented with less adverse effects than the group that underwent MVD plus rhizotomy. Although SRS may be a viable alternative treatment for GPN, further studies must be done to evaluate long-term treatment efficacy.

Concurrent Administration of Immune Checkpoint Inhibitors and Single Fraction Stereotactic Radiosurgery in Patients With Non-Small Cell Lung Cancer, Melanoma, and Renal Cell Carcinoma Brain Metastases is Not Associated With an Increased Risk of Radiation Necrosis Over Nonconcurrent Treatment: An International Multicenter Study of 657 Patients

PURPOSE

Stereotactic radiosurgery (SRS) and immune checkpoint inhibitors (ICI) are highly effective treatments for brain metastases, particularly when these therapies are administered concurrently. However, there are limited data reporting the risk of radiation necrosis (RN) in this setting.

METHODS AND MATERIALS

Patients with brain metastases from primary non-small cell lung cancer, renal cell carcinoma, or melanoma treated with SRS and ICI were considered. Time-to-event analyses were conducted for any grade RN and symptomatic RN (SRN) with death incorporated as a competing risk. As a secondary analysis, recursive partitioning analysis (RPA) was used for model development, and a loop of potential models was analyzed, with the highest-fidelity model selected. Brain V12 Gy thresholds identified on RPA were then incorporated into the competing risks analysis. Concurrent SRS and ICI administration.

RESULTS

Six hundred fifty-seven patients with 4182 brain metastases across 11 international institutions were analyzed. The median follow-up for all patients was 13.4 months. The median follow-up was 12.8 months and 14.1 months for the concurrent and nonconcurrent groups, respectively (P = .03). The median patient age was 66 years, and the median Karnofsky Performance Status was 90. In patients with any grade RN, 1- and 2-year rates were 6.4% and 9.9%, respectively. In patients with SRN, 1- and 2-year rates were 4.8% and 7.2%, respectively. On RPA, the highest-fidelity models consistently identified V12 Gy as the dominant variable predictive of RN. Three risk groups were identified by V12 Gy: (1) < 12 cm³; (2) 20 cm³ ≥ V12 Gy ≥ 12 cm³; (3) V12 Gy > 20 cm³. In patients with any grade RN, 1-year rates were 3.7% (V12 Gy < 12 cm³), 10.3% (20 cm³ ≥ V12 Gy ≥ 12 cm³), and 12.6% (V12 Gy > 20 cm³); the 2-year rates were 7.5% (V12 Gy < 12 cm³), 13.8% (20 cm³ ≥ V12 Gy ≥ 12 cm³), and 15.4% (V12 Gy > 20 cm³) (P < 0.001). In patients with any SRN, 1-year rates were 2.4% (V12 Gy < 12 cm³), 8.9% (20 cm³ ≥ V12 Gy ≥ 12 cm³), and 10.3% (V12 Gy > 20 cm³); the 2-year rates were 4.4% (V12 Gy < 12 cm³), 12.4% (20 cm³ ≥ V12 Gy ≥ 12 cm³), and 13.1% (V12 Gy > 20 cm³; P < 0.001). There were no statistically significant differences in rates of any grade RN or SRN when accounting for therapy timing for all patients and by V12 risk group identified on RPA.

CONCLUSIONS

The use of SRS and ICI results in a low risk of any grade RN and SRN. This risk is not increased with concurrent administration. Therefore, ICI can safely be administered within 4-weeks of SRS. Three risk groups based on V12 Gy were identified, which clinicians may consider to further reduce rates of RN.

Effects of Neuroanatomic Structural Distances on Pituitary Function After Stereotactic Radiosurgery: A Multicenter Study

BACKGROUND

Delayed hypopituitarism is the most common complication after stereotactic radiosurgery (SRS) for pituitary adenomas.

OBJECTIVE

To investigate the relationship between neuroanatomic structure distances from the radiation target and anterior pituitary function preservation after SRS through multicenter study.

METHODS

We retrospectively reviewed the International Radiosurgery Research Foundation database from January 2002 to December 2021 for adult patients undergoing SRS for pituitary adenomas with >6 months of follow-up. Distances between centers or edges of hypothalamic-pituitary axis structures and SRS target volumes were measured using MRI. The primary outcome was anterior pituitary function preservation. Predictors were analyzed using multivariable logistic regression and area under the receiver operating curve (AUROC) curve analyses.

RESULTS

Four hundred eighty-seven patients were categorized by preservation (n = 384) and no preservation (n = 103) of anterior pituitary function. The mean margin dose was 19.1(6.2) Gy. Larger distance from the center of the stalk to the tumor margin isodose was a positive predictor (adjusted odds ratio [aOR] = 1.162 [1.046-1.291], P = .005), while pre-SRS hypopituitarism (aOR = 0.646 [0.405-1.031], P = .067) and larger treatment volume (aOR = 0.965 [0.929-1.002], P = .061) were near negative predictors of the primary outcome. An interaction between the treatment volume and center stalk to margin isodose distance was found (aOR = 0.980 [0.961-0.999], P = .045). Center stalk to margin isodose distance had an AUROC of 0.620 (0.557-0.693), at 3.95-mm distance. For patients with treatment volumes of <2.34 mL, center stalk to margin isodose distance had an AUROC of 0.719 (0.614-0.823), at 2.95-mm distance.

CONCLUSION

Achieving a distance between the center of the pituitary stalk and the tumor margin isodose ≥3.95 mm predicted anterior pituitary function preservation. For smaller treatment volumes <2.34 mL, the optimal distance was ≥2.95 mm. This may be modifiable during trans-sphenoidal resection to preserve pituitary function.

Concurrent Administration of Immune Checkpoint Inhibitors and Stereotactic Radiosurgery Is Well-Tolerated in Patients With Melanoma Brain Metastases: An International Multicenter Study of 203 Patients

BACKGROUND

Melanoma brain metastases are commonly treated with stereotactic radiosurgery (SRS) and immune checkpoint inhibitors (ICIs). However, the toxicity of these 2 treatments is largely unknown when administered concurrently.

OBJECTIVE

To evaluate the risk of radiation necrosis (RN) with concurrent and nonconcurrent SRS and ICIs.

METHODS

The guidelines from the Strengthening the Reporting of Observational Studies in Epidemiology checklist were used. Inverse probability of treatment weighting, univariable and multivariable logistic regression, and the Kaplan-Meier method was utilized.

RESULTS

There were 203 patients with 1388 brain metastases across 11 international institutions in 4 countries with a median follow-up of 15.6 months. The rates of symptomatic RN were 9.4% and 8.2% in the concurrent and nonconcurrent groups, respectively ( P =.766). On multivariable logistic regression, V12 ≥ 10 cm 3 (odds ratio [OR]: 2.76; P =.006) and presence of BRAF mutation (OR: 2.20; P =.040) were associated with an increased risk of developing symptomatic RN; the use of concurrent over nonconcurrent therapy was not associated with an increased risk (OR: 1.06; P =.877). There were 20 grade 3 toxic events reported, and no grade 4 events reported. One patient experienced a grade 5 intracranial hemorrhage. The median overall survival was 36.1 and 19.8 months for the concurrent and nonconcurrent groups (log-rank P =.051), respectively.

CONCLUSION

Concurrent administration of ICIs and SRS are not associated with an increased risk of RN. Tumors harboring BRAF mutation, or perhaps prior exposure to targeted agents, may increase this risk. Radiosurgical optimization to maintain V12 < 10 cm 3 is a potential strategy to reduce the risk of RN.

Stereotactic radiosurgery and local control of brain metastases from triple-negative breast cancer

OBJECTIVE

Stereotactic radiosurgery (SRS) is an effective treatment for intracranial metastatic disease, but its role in triple-negative breast cancer requires further study. Herein, the authors report overall survival (OS) and local tumor control in a multiinstitutional cohort with triple-negative breast cancer metastases treated with SRS.

METHODS

Patients treated from 2010 to 2019 at 9 institutions were included in this retrospective study if they had biopsy-proven triple-negative breast cancer with intracranial metastatic lesions treated with SRS. Patients were excluded if they had undergone prior SRS, whole-brain radiation therapy, or resection of the metastatic lesions. A retrospective chart review was conducted to determine OS, local control, and treatment efficacy.

RESULTS

Sixty-eight patients with 315 treated lesions were assessed. Patients had a median Karnofsky Performance Status of 80 (IQR 70-90) and age of 57 years (IQR 48-67 years). Most treated patients had 5 or fewer intracranial lesions, with 34% of patients having a single lesion. Treated lesions were small, having a median volume owf 0.11 cm3 (IQR 0.03-0.60 cm3). Patients were treated with a median margin dose of 18 Gy (IQR 18-20 Gy) to the median 71% isodose line (IQR 50%-84%). Overall, patients had a 1-year OS of 43% and 2-year OS of 20%. Most patients (88%) were followed until death, by which time local tumor progression had occurred in only 7% of cases. Furthermore, 76% of the lesions demonstrated regression. Tumor volume was correlated with local tumor progression (p = 0.012). SRS was very well tolerated, and only 3 patients (5%) developed symptomatic radiation necrosis.

CONCLUSIONS

SRS is a safe and efficacious treatment for well-selected patients with triple-negative breast cancer, especially for those with a favorable performance status and small- to moderate-volume metastatic lesions.

Preoperative stereotactic radiosurgery in the management of brain metastases and gliomas

Stereotactic radiosurgery (SRS) is the delivery of a high dose ionizing radiation in a highly conformal manner, which allows for significant sparing of nearby healthy tissues. It is typically delivered in 1-5 sessions and has demonstrated safety and efficacy across multiple intracranial neoplasms and functional disorders. In the setting of brain metastases, postoperative and definitive SRS has demonstrated favorable rates of tumor control and improved cognitive preservation compared to conventional whole brain radiation therapy. However, the risk of local failure and treatment-related complications (e.g. radiation necrosis) markedly increases with larger postoperative treatment volumes. Additionally, the risk of leptomeningeal disease is significantly higher in patients treated with postoperative SRS. In the setting of high grade glioma, preclinical reports have suggested that preoperative SRS may enhance anti-tumor immunity as compared to postoperative radiotherapy. In addition to potentially permitting smaller target volumes, tissue analysis may permit characterization of DNA repair pathways and tumor microenvironment changes in response to SRS, which may be used to further tailor therapy and identify novel therapeutic targets. Building on the work from preoperative SRS for brain metastases and preclinical work for high grade gliomas, further exploration of this treatment paradigm in the latter is warranted. Presently, there are prospective early phase clinical trials underway investigating the role of preoperative SRS in the management of high grade gliomas. In the forthcoming sections, we review the biologic rationale for preoperative SRS, as well as pertinent preclinical and clinical data, including ongoing and planned prospective clinical trials.

Radiotherapy for elderly patients with glioblastoma: an assessment of hypofractionation and modern treatment techniques

Glioblastoma (GBM) is a disease with a poor prognosis. For decades, radiotherapy has played a critical role in the management of GBM. The standard of care radiation prescription is 60 Gy in 30 fractions, but landmark trials have historically excluded patients older than 70 years. Currently, there is considerable variation in the management of elderly patients with GBM. Shortened radiation treatment (hypofractionated) regimens have been explored since conventional treatment schedules are lengthy and many elderly patients have functional, cognitive, and social limitations. Clinical trials have demonstrated the effectiveness of hypofractionated radiotherapy (40 Gy in 15 fractions) to treat elderly or frail patients with GBM. Although previous studies have suggested these unique hypofractionation prescriptions effectively treat these patients, there are many avenues for improvement in this patient population. Herein, we describe the unique tumor biology of glioblastoma, key hypofractionated radiotherapy studies, and health-related quality of life (HRQOL) studies for elderly patients with GBM. Hypofractionated radiation has emerged as a shortened alternative and retrospective studies have suggested survival outcomes are similar for elderly patients with GBM. Prospective studies comparing hypofractionation with conventional treatment regiments are warranted. In addition to evaluating survival outcomes, HRQOL endpoints should be incorporated into future studies.

Imaging-defined necrosis after treatment with single-fraction stereotactic radiosurgery and immune checkpoint inhibitors and its potential association with improved outcomes in patients with brain metastases: an international multicenter study of 697 patients

OBJECTIVE

Immune checkpoint inhibitors (ICIs) and stereotactic radiosurgery (SRS) are commonly utilized in the management of brain metastases. Treatment-related imaging changes (TRICs) are a frequently observed clinical manifestation and are commonly classified as imaging-defined radiation necrosis. However, these findings are not well characterized and may predict a response to SRS and ICIs. The objective of this study was to investigate predictors of TRICs and their impact on patient survival.

METHODS

This retrospective multicenter cohort study was conducted through the International Radiosurgery Research Foundation. Member institutions submitted de-identified clinical and dosimetric data for patients with non-small cell lung cancer (NSCLC), melanoma, and renal cell carcinoma (RCC) brain metastases that had been treated with SRS and ICIs. Data were collected from March 2020 to February 2021. Univariable and multivariable Cox and logistic regression analyses were performed. The Kaplan-Meier method was used to evaluate overall survival (OS). The diagnosis-specific graded prognostic assessment was used to guide variable selection. TRICs were determined on the basis of MRI, PET/CT, or MR spectroscopy, and consensus by local clinical providers was required.

RESULTS

The analysis included 697 patients with 4536 brain metastases across 11 international institutions in 4 countries. The median follow-up after SRS was 13.6 months. The median age was 66 years (IQR 58-73 years), 54.1% of patients were male, and 57.3%, 36.3%, and 6.4% of tumors were NSCLC, melanoma, and RCC, respectively. All patients had undergone single-fraction radiosurgery to a median margin dose of 20 Gy (IQR 18-20 Gy). TRICs were observed in 9.8% of patients. The median OS for all patients was 24.5 months. On univariable analysis, Karnofsky Performance Status (KPS; HR 0.98, p < 0.001), TRICs (HR 0.67, p = 0.03), female sex (HR 0.67, p < 0.001), and prior resection (HR 0.60, p = 0.03) were associated with improved OS. On multivariable analysis, KPS (HR 0.98, p < 0.001) and TRICs (HR 0.66, p = 0.03) were associated with improved OS. A brain volume receiving ≥ 12 Gy of radiation (V12Gy) ≥ 10 cm3 (OR 2.78, p < 0.001), prior whole-brain radiation therapy (OR 3.46, p = 0.006), and RCC histology (OR 3.10, p = 0.01) were associated with an increased probability of developing TRICs. The median OS rates in patients with and without TRICs were 29.0 and 23.1 months, respectively (p = 0.03, log-rank test).

CONCLUSIONS

TRICs following ICI and SRS were associated with a median OS benefit of approximately 6 months in this retrospective multicenter study. Further prospective study and additional stratification are needed to validate these findings and further elucidate the role and etiology of this common clinical scenario.