Stereotactic radiosurgery of the postoperative resection cavity for brain metastases

Stereotactic radiosurgery versus whole-brain radiotherapy for intracranial metastases: A systematic review and meta-analysis

Background

Brain metastasis has a negative influence on the morbidity and mortality of cancer patients. Conventionally, whole-brain radiotherapy (WBRT) was favored as the standard treatment for brain metastases. However, it has been linked to a significant decline in neuro-cognitive function and poor quality of life. Stereotactic radiosurgery (SRS) has recently gained prominence as an alternative modality, considering that it provides targeted high-dose radiation while minimizing adverse effects. This study evaluates the efficacy and safety of SRS versus WBRT in patients with intracranial metastases.

Methods

According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, through July 2024, we searched PubMed, Scopus, and Web of Science for articles comparing WBRT and SRS in patients with intracranial metastases. Outcomes included local and distant recurrence, leptomeningeal disease (LMD), and survival. We also used a random-effect model to perform a meta-analysis.

Results

The findings revealed no significant differences in local (risk ratio [RR] = 0.70, 95% confidence interval [CI] [0.46, 1.06]) or distant recurrence rates (RR = 0.83, 95% CI [0.54, 1.28], P = 0.41) between WBRT and SRS. However, SRS was associated with a greater risk of post-radiation LMD (hazard ratio [HR] = 3.09, 95% CI [1.47, 6.49], P = 0.003). Survival rates at 1 year (RR = 1.03, 95% CI [0.83, 1.29], P = 0.76) and 5 years (RR = 0.89, 95% CI [0.39, 2.04], P = 0.78) demonstrated no significant differences.

Conclusion

SRS and WBRT exhibited similar recurrence rates and overall survival (OS) at 1 and 5 years, with WBRT being more effective in managing post-radiation LMD. SRS patients, on the other hand, had longer OS when measured in months.

Comparative evaluation of outcomes amongst different radiosurgery management paradigms for patients with large brain metastasis

INTRODUCTION

This study compares four management paradigms for large brain metastasis (LMB): fractionated SRS (FSRS), staged SRS (SSRS), resection and postoperative-FSRS (postop-FSRS) or preoperative-SRS (preop-SRS).

METHODS

Patients with LBM (≥ 2 cm) between July 2017 and January 2022 at a single tertiary institution were evaluated. Primary endpoints were local failure (LF), radiation necrosis (RN), leptomeningeal disease (LMD), a composite of these variables, and distant intracranial failure (DIF). Gray's test compared cumulative incidence, treating death as a competing risk with a random survival forests (RSF) machine-learning model also used to evaluate the data.

RESULTS

183 patients were treated to 234 LBMs: 31.6% for postop-FSRS, 28.2% for SSRS, 20.1% for FSRS, and 20.1% for preop-SRS. The overall 1-year composite endpoint rates were comparable (21 vs 20%) between nonoperative and operative strategies, but 1-year RN rate was 8 vs 4% (p = 0.012), 1-year overall survival (OS) was 48 vs. 69% (p = 0.001), and 1-year LMD rate was 5 vs 10% (p = 0.052). There were differences in the 1-year RN rates (7% FSRS, 3% postop-FSRS, 5% preop-SRS, 10% SSRS, p = 0.037). With RSF analysis, the out-of-bag error rate for the composite endpoint was 47%, with identified top-risk factors including widespread extracranial disease, > 5 total lesions, and breast cancer histology.

CONCLUSION

This is the first study to conduct a head-to-head retrospective comparison of four SRS methods, addressing the lack of randomized data in LBM literature amongst treatment paradigms. Despite patient characteristic trends, no significant differences were found in LF, composite endpoint, and DIF rates between non-operative and operative approaches.

Novel radiotherapeutic strategies in the management of brain metastases: Challenging the dogma

The role of radiation therapy in the management of brain metastasis is evolving. Advancements in machine learning techniques have improved our ability to both detect brain metastasis and our ability to contour substructures of the brain as critical organs at risk. Advanced imaging with PET tracers and magnetic resonance imaging-based artificial intelligence models can now predict tumor control and differentiate tumor progression from radiation necrosis. These advancements will help to optimize dose and fractionation for each patient's lesion based on tumor size, histology, systemic therapy, medical comorbidities/patient genetics, and tumor molecular features. This review will discuss the current state of brain directed radiation for brain metastasis. We will also discuss future directions to improve the precision of stereotactic radiosurgery and optimize whole brain radiation techniques to improve local tumor control and prevent cognitive decline without forming necrosis.

Postoperative stereotactic radiosurgery and hypofractionated radiotherapy for brain metastases using Gamma Knife and CyberKnife: a dual-center analysis

BACKGROUND

Postoperative stereotactic radiosurgery (SRS) and hypofractionated stereotactic radiotherapy (hFSRT) to tumor cavities is emerging as a new standard of care after resection of brain metastases. Both Gamma Knife (GK) and CyberKnife (CK) are modalities commonly used for stereotactic radiotherapy, but fractional schemes are not consistent. The objective of this study was to evaluate outcomes in patients receiving postoperative stereotactic radiotherapy of resected brain metastases (BM) using different fractionation schedules and modalities in two large centers.

METHODS

Patients with newly diagnosed BM who underwent postoperative SRS or hFSRT with either GK or CK at two large cancer centers were retrospectively evaluated. We analyzed local control (LC), regional control (RC) and overall survival (OS).

RESULTS

From April 14th to May 18th, 2020, 79 patients with 81 resection cavities were treated. Forty-seven patients (59.5%) received GK and 32 patients (40.5%) received CK treatment. Fifty-four cavities (66.7%) were treated with hFSRT and 27 (33.3%) with SRS. The most common hFSRT and SRS scheme was 3x10 Gy and 1x16 Gy, respectively. Median OS was 11.7 months with survival rates of 44.7% at 1 year and 18.5% at 2 years. LC was 83.3% after 1 year. Median time to regional progression was 12.0 months with RC rates of 61.1% at 6 months and 41.0% at 12 months. There was no difference in OS, LC or RC between GK and CK treatments or SRS and hFSRT.

CONCLUSIONS

Both SRS and hFSRT provide high local control rates in resected BM regardless of the applied modality.

Socio-economic disparities influence likelihood of post-operative radiation to resection cavities of metastatic brain tumors

PURPOSE

Irradiating the surgical bed of resected brain metastases improves local and distant disease control. Over time, stereotactic radiosurgery (SRS) has replaced whole brain radiotherapy (WBRT) as the treatment standard of care because it minimizes long-term damage to neuro-cognition. Despite this data and growing adoption, socio-economic disparities in clinical access can result in sub-standard care for some patient populations. We aimed to analyze the clinical and socio-economic characteristics of patients who did not receive radiation after surgical resection of brain metastasis.

METHODS

Our sample was obtained from Clinformatics® Data Mart Database and included all patients from 2004 to 2021 who did or did not receive radiation treatment within sixty days after resection of tumors metastatic to the brain. Regression analysis was done to identify factors responsible for loss to adjuvant radiation treatment.

RESULTS

Of 8362 patients identified who had undergone craniotomy for resection of metastatic brain tumors, 3430 (41%) patients did not receive any radiation treatment. Compared to patients who did receive some form of radiation treatment (SRS or WBRT), patients who did not get any form of radiation were more likely to be older (p = 0.0189) and non-white (p = 0.008). Patients with Elixhauser Comorbidity Index ≥3 were less likely to receive radiation treatment (p < 0.01). Fewer patients with household income ≥ $75,000 did not receive radiation treatment (p < 0.01).

CONCLUSION

Age, race, household income, and comorbidity status were associated with differential likelihood to receive post-operative radiation treatment.

Advances in Radiotherapy for Brain Metastases

Radiotherapy remains a cornerstone treatment of brain metastases. With new treatment advances, patients with brain metastases are living longer, and finding solutions for mitigating treatment-related neurotoxicity and improving quality of life is important. Historically, whole-brain radiation therapy (WBRT) was widely used but treatment options such as hippocampal sparing WBRT and stereotactic radiosurgery (SRS) have emerged as promising alternatives. Herein, we discuss the recent advances in radiotherapy for brain metastases including the sparing of critical structures that may improve long-term neurocognitive outcomes (eg, hippocampus, fornix) that may improve long-term neurocognitive outcome, evidence supporting preoperative and fractionated-SRS, and treatment strategies for managing radiation necrosis.

Stereotactic Radiosurgery for Brain Metastases in Patients With a Heterozygous Germline Ataxia Telangiectasia Mutated Gene

Germline mutations in the ataxia telangiectasia mutated (ATM) gene are associated with increased radiation sensitivity. Present literature lacks consensus on whether patients with heterozygous germline ATM mutations may be at greater risk of radiation-associated toxicities when treated with radiation therapy (RT), and there is little data considering more modern and conformal RT techniques such as stereotactic radiosurgery (SRS). Our report presents two cases of patients with heterozygous germline ATM mutations treated with SRS for brain metastases. One patient developed grade 3 radiation necrosis (RN) of an irradiated 16.3 cm³ resection cavity, but did not develop RN at other sites of punctate brain metastases treated with SRS. Similarly, the second report describes a patient who did not develop RN at any of the 31 irradiated sites of sub-centimeter (all ≤5 mm) brain metastases. The described cases demonstrate that some patients with germline ATM variants can safely undergo SRS for smaller brain metastases; however, clinical caution should be considered for patients with larger targets or a history of prior radiation toxicity. Given these findings and the lingering uncertainty surrounding the degree of radiosensitivity across ATM variants, future research is needed to determine whether more conservative dose-volume limits would potentially mitigate the risk of RN when treating larger brain metastases in this radiosensitive population.

Mutational Status and Clinical Outcomes Following Systemic Therapy with or without Focal Radiation for Resected Melanoma Brain Metastases

BACKGROUND

Brain metastases occur frequently in advanced melanoma and traditionally require surgery and radiation therapy. New evidence demonstrates that systemic therapies are effective for controlling metastatic melanoma brain metastases. This study evaluated outcomes after resection of melanoma brain metastases treated with systemic therapy, with or without focal radiotherapy.

METHODS

All patients received immunotherapy or BRAF/MEK inhibitors preoperatively or in the immediate 3 months postoperatively. Resection cavity failure, distant central nervous system progression, and adverse radiation effects were reported in the presence and absence of focal radiotherapy using the Kaplan-Meier method.

RESULTS

Between 2011 and 2020, 37 resection cavities in 29 patients met criteria for analysis. Of lesions, 22 (59%) were treated with focal radiotherapy, and 15 (41%) were treated with targeted therapy or immunotherapy alone. The 12- and 24-month freedom from local recurrence was 64.8% (95% confidence interval [CI] 42.1%-99.8%) and 46.3% (95% CI 24.5%-87.5%), respectively, for systemic therapy alone and 93.3% (95% CI 81.5%-100%) at both time points for focal radiotherapy (P = 0.01). On univariate analysis, focal radiotherapy was the only significant factor associated with reduction of local recurrence risk (hazard ratio 0.10, 95% CI 0.01-0.85; P = 0.04). There were no significant differences in central nervous system progression-free survival or overall survival between patients who received systemic therapy plus focal radiotherapy compared with systemic therapy alone. BRAF mutation status was reviewed for either the brain metastasis (n = 9 patients, 31%) or the primary site (n = 20 patients, 69%), and patients harboring BRAFV600E mutations had worse progression-free survival (P = 0.043).

CONCLUSIONS

Focal radiotherapy with systemic therapy for resected melanoma brain metastases significantly decreased resection cavity recurrence compared with systemic therapy alone. BRAF mutation status correlated with poorer outcomes.

Gamma Knife Radiosurgery Irradiation of Surgical Cavity of Brain Metastases: Factor Analysis and Gene Mutations

(1) Background: Surgical resection for the removal of brain metastases often fails to prevent tumor recurrence within the surgical cavity; hence, researchers are divided as to the benefits of radiation treatment following surgical resection. This retrospective study assessed the effects of post-operative stereotactic radiosurgery (SRS) on local tumor control and overall survival. (2) Methods: This study examined the demographics, original tumor characteristics, and surgical outcomes of 97 patients who underwent Gamma Knife Radiosurgery (GKRS) treatment (103 brain metastases). Kaplan-Meier plots and Cox regression were used to correlate clinical features to tumor control and overall survival. (3) Results: The overall tumor control rate was 75.0% and overall 12-month survival was 89.6%. Tumor control rates in the radiation group versus the non-radiation group were as follows: 12 months (83.1% vs. 57.7%) and 24 months (66.1% vs. 50.5%). During the 2-year follow-up period after SRS, the intracranial response rate was higher in the post-craniotomy radiation group than in the non-radiation group (p = 0.027). Cox regression multivariate analysis determined that post-craniotomy irradiation of the surgical cavity is predictive of tumor control (p = 0.035). However, EGFR mutation was not predictive of overall survival or tumor control. (4) Conclusions: Irradiating the surgical cavity after surgery can enhance local tumor control; however, it does not have a significant effect on overall survival.

Metastatic Lesions of the Brain and Spine

Brain and spinal metastases are common in cancer patients and are associated with significant morbidity and mortality. Continued advancement in the systemic care of cancer has increased the life expectancy of patients, and consequently, the incidence of brain and spine metastasis has increased. There has been an increase in the understanding of oncogenic mutations, and research has also demonstrated spatial and temporal mutations in patients that may drive overall treatment resistance and failure. Combinatory treatments with radiation, surgery, and newer systemic therapies have continued to increase the life expectancy of patients with brain and spine metastases. Given the overall complexity of brain and spine metastases, this chapter aims to give a comprehensive overview and cover important topics concerning brain and spine metastases. This will include the molecular, genetic, radiographic, surgical, and non-surgical treatments of brain and spinal metastases.

Dosimetric Analysis of Intra-Fraction Motion Detected by Surface-Guided Radiation Therapy During Linac Stereotactic Radiosurgery

Purpose

Stereotactic radiosurgery (SRS) immobilization with an open face mask is more comfortable and less invasive than frame based, but concerns about intrafraction motion must be addressed. Surface-guided radiation therapy (SGRT) is an attractive option for intrafraction patient monitoring because it is continuous, has submillimeter accuracy, and uses no ionizing radiation. The purpose of this study was to investigate the dosimetric consequences of uncorrected intrafraction patient motion detected during frameless linac-based SRS.

Methods and Materials

Fifty-five SRS patients were monitored during treatment using SGRT between January 1, 2017, and September 30, 2020. If SGRT detected motion >1 mm, imaging was repeated and the necessary shifts were made before continuing treatment. For the 25 patients with intrafraction 3-dimensional vector shifts of ≥1 mm, we moved the isocenter in the planning system using the translational shifts from the repeat imaging and recalculated the plans to determine the dosimetric effect of the shifts. Planning target volume (PTV) coverage, minimum gross tumor volume (GTV) dose (relative and absolute), and normal brain V12 were evaluated. Wilcoxon signed rank tests were used to compare planned and simulated dosimetric parameters and median 2 sample tests were used to investigate these differences between cone and multileaf collimator (MLC) plans.

Results

For simulated plans, V12 increased by a median of 0.01 cc (P = .006) and relative GTV minimum dose and PTV coverage decreased by a median of 15.8% (P < .001) and 10.2 % (P < .001), respectively. Absolute minimum GTV dose was found to be significantly lower in the simulated plans (P < .001). PTV coverage decreased more for simulated cone plans than for simulated MLC plans (11.6% vs 4.7%, P = .011) but median V12 differences were found to be significantly larger for MLC plans (-0.34 cc vs -0.01 cc, P = .011). Differences in GTV minimum dose between cone and MLC plans were not statistically significant.

Conclusions

SGRT detected clinically meaningful intrafraction motion during frameless SRS, which could lead to large underdoses and increased normal brain dose if uncorrected.

Neoadjuvant stereotactic radiosurgery for brain metastases: a new paradigm

OBJECTIVE

For patients with surgically accessible solitary metastases or oligometastatic disease, treatment often involves resection followed by postoperative stereotactic radiosurgery (SRS). This strategy has several potential drawbacks, including irregular target delineation for SRS and potential tumor "seeding" away from the resection cavity during surgery. A neoadjuvant (preoperative) approach to radiation therapy avoids these limitations and offers improved patient convenience. This study assessed the efficacy of neoadjuvant SRS as a new treatment paradigm for patients with brain metastases.

METHODS

A retrospective review was performed at a single institution to identify patients who had undergone neoadjuvant SRS (specifically, Gamma Knife radiosurgery) followed by resection of a brain metastasis. Kaplan-Meier survival and log-rank analyses were used to evaluate risks of progression and death. Assessments were made of local recurrence and leptomeningeal spread. Additionally, an analysis of the contemporary literature of postoperative and neoadjuvant SRS for metastatic disease was performed.

RESULTS

Twenty-four patients who had undergone neoadjuvant SRS followed by resection of a brain metastasis were identified in the single-institution cohort. The median age was 64 years (range 32-84 years), and the median follow-up time was 16.5 months (range 1 month to 5.7 years). The median radiation dose was 17 Gy prescribed to the 50% isodose. Rates of local disease control were 100% at 6 months, 87.6% at 12 months, and 73.5% at 24 months. In 4 patients who had local treatment failure, salvage therapy included repeat resection, laser interstitial thermal therapy, or repeat SRS. One hundred thirty patients (including the current cohort) were identified in the literature who had been treated with neoadjuvant SRS prior to resection. Overall rates of local control at 1 year after neoadjuvant SRS treatment ranged from 49% to 91%, and rates of leptomeningeal dissemination from 0% to 16%. In comparison, rates of local control 1 year after postoperative SRS ranged from 27% to 91%, with 7% to 28% developing leptomeningeal disease.

CONCLUSIONS

Neoadjuvant SRS for the treatment of brain metastases is a novel approach that mitigates the shortcomings of postoperative SRS. While additional prospective studies are needed, the current study of 130 patients including the summary of 106 previously published cases supports the safety and potential efficacy of preoperative SRS with potential for improved outcomes compared with postoperative SRS.

Pre-operative Stereotactic Radiosurgery for Cerebral Metastatic Disease: A Retrospective Dose-Volume Study

BACKGROUND AND PURPOSE

Stereotactic radiosurgery (SRS) after maximal safe resection is an accepted treatment strategy for patients with cerebral metastatic disease. Despite its high conformality profile, the incidence of radionecrosis (RN) remains high. SRS delivered pre-operatively could be associated with a reduced incidence of RN. We sought to evaluate whether neoadjuvant SRS could reduce radiotherapy doses in a cohort of patients treated with post-operative SRS.

METHODS

A cohort of 47 brain metastases (BM) treated at 2 academic institutions was retrospectively analyzed. Subjects underwent surgical extirpation of BMs and subsequent SRS to surgical bed. Post-operative volumetric and dosimetric data was collected from records or recreations of delivered plans; pre-operative data were derived from hypothetical radiotherapy courses and compared using Wilcoxon signed-rank tests.

RESULTS

Higher planned tumor volume post-operatively (median[IQR] 12.28 [6.54, 18.69]cc vs. 10.20 [4.53, 21.70]cc respectively, p=0.4150) was observed. The median prescribed radiotherapy dose (DRx) was 16Gy pre-operatively and 24Gy post-operatively(p<0.0001). Further investigations revealed improved pre-operative conformity index (1.23[1.20, 1.29] vs. 1.29[1.23, 1.39], p=0.0098) and gradient index (2.72[2.59, 2.98] vs. 2.94[2.69, 3.47], p=0.0004). A significant difference was found in normal brain tissue exposed to 10Gy (12.97[6.78, 25.54]cc vs. 32.13[19.42, 48.40]cc, p<0.0001), 12Gy (9.31[4.56, 17.43]cc vs. 23.80[14.74, 36.56]cc, p<0.0001), and 14Gy (5.62[3.23, 11.61]cc vs. 17.47[9.00, 28.31]cc, p<0.0001), favoring pre-operative SRS.

CONCLUSIONS

Neoadjuvant SRS is associated reduced DRx, better conformality profile and decreased radiation to normal tissue. These findings could support the use of neoadjuvant SRS for the treatment of BMs.

Impact of socio-economic factors on radiation treatment after resection of metastatic brain tumors: trends from a private insurance database

BACKGROUND

Stereotactic radiosurgery (SRS) to the surgical bed of resected brain metastases is now considered the standard of care due to its advantages over whole brain radiation therapy (WBRT). Despite the upward trend in SRS adoption since the 2000s, disparities have been reported suggesting that socio-economic factors can influence SRS utilization.

OBJECTIVE

To analyze recent trends in SRS use and identify factors that influence treatment.

METHODS

We conducted a retrospective cohort study with the Optum Commercial Claims and Encounters Database and included all patients from 2004 to 2021 who received SRS or WBRT within 60 days after resection of tumors metastatic to the brain.

RESULTS

A total of 3495 patients met the inclusion and exclusion criteria. There were 1998 patients in the SRS group and 1497 patients in the WBRT group. SRS use now supersedes WBRT by a wide margin. Lung, breast and colon were the most common sites of primary tumor. Although we found no significant differences based on race among the treatment groups, patients with annual household income greater than $75,000 and those with some college or higher education are significantly more likely to receive SRS (OR 1.44 and 1.30; 95% CI 1.18-1.76 and 1.08-1.56; P = 0.001 and 0.005, respective). Patients with Elixhauser Comorbidity Index of three or more were significantly more likely to receive SRS treatment.

CONCLUSION

The use of post-surgical SRS for brain metastasis has increased significantly over time, however education and income were associated with differential SRS utilization.

Salvage brachytherapy for multiply recurrent metastatic brain tumors: a matched-case analysis

Background

Patients with recurrent brain metastases who have exhausted external radiation options pose a treatment challenge in the setting of advances in systemic disease control which have improved quality of life and survival. Brachytherapy holds promise as salvage therapy given its ability to enforce surgical cytoreduction and minimize regional toxicity. This study investigates the role of salvage brachytherapy in maintaining local control for recurrent metastatic lesions.

Methods

We retrospectively reviewed our institution’s experience with brachytherapy in patients with multiply recurrent cerebral metastases who have exhausted external radiation treatment options (14 cases). The primary outcome of the study was freedom from local recurrence (FFLR). To capture the nuances of tumor biology, we compared FFLR achieved by brachytherapy to the preceding treatment for each patient. We further compared the response to brachytherapy in patients with lung cancer (8 cases) against a matched cohort of maximally radiated lung brain metastases (10 cases).

Results

Brachytherapy treatment conferred significantly longer FFLR compared to prior treatments (median 7.39 vs 5.51 months, P = .011) for multiply recurrent brain metastases. Compared to an independent matched cohort, brachytherapy demonstrated superior FFLR (median 8.49 vs 1.61 months, P = .004) and longer median overall survival (11.07 vs 5.93 months, P = .055), with comparable side effects.

Conclusion

Brachytherapy used as salvage treatment for select patients with a multiply recurrent oligometastatic brain metastasis in the setting of well-controlled systemic disease holds promise for improving local control in this challenging patient population.

Management Strategies for Large Brain Metastases

Brain metastases represent the most common intracranial neoplasm and pose a significant disease burden on the individual and the healthcare system. Although whole brain radiation therapy was historically a first line approach, subsequent research and technological advancements have resulted in a larger armamentarium of strategies for treatment of these patients. While chemotherapeutic options remain limited, surgical resection and stereotactic radiosurgery, as well as their combination therapies, have shifted the paradigms for managing intracranial metastatic disease. Ultimately, no single treatment is shown to be consistently effective across patient groups in terms of overall survival, local and distant control, neurocognitive function, and performance status. However, close consideration of patient and tumor characteristics may help delineate more favorable treatment strategies for individual patients. Here the authors present a review of the recent literature surrounding surgery, whole brain radiation therapy, stereotactic radiosurgery, and combination approaches.

Recent Advances and Applications of Radiation Therapy for Brain Metastases

PURPOSE OF REVIEW

Radiation therapy (RT) is a mainstay of treatment for brain metastases from solid tumors. Treatment of these patients is complex and should focus on minimizing symptoms, preserving functional status, and prolonging survival.

RECENT FINDINGS

Whole-brain radiotherapy (WBRT) can lead to toxicity, and while it does reduce recurrence in the CNS, this has not been shown to provide a survival benefit. Recent advances focus on reducing the toxicity of WBRT or using more targeted radiation therapy. New paradigms including the use of proton RT for leptomeningeal metastases (LM) and stereotactic radiosurgery (SRS) before craniotomy hold promise in improving treatment efficacy and reducing toxicity. Omission or replacement of WBRT is often safe and the use of SRS is expanding to include patients with more lesions and preoperative RT. Proton RT holds promise for LM. Progress is being made in improving patient-centered outcomes and reducing toxicity for patients with brain metastases.

Multimodality durable salvage of recurrent brain metastases refractory to LITT, SRS and immunotherapy with resection and cesium-131 brachytherapy: case report and literature review

Brain metastases (BrM) are treated with multimodality therapy, however the optimal combination and timing of modalities in the setting of recurrent tumours that have failed prior treatments remain poorly defined. We present a case of a patient with biopsy-confirmed renal cell carcinoma BrM with good performance status initially treated with laser interstitial thermal ablation therapy (LITT) followed by stereotactic radiosurgery and dual checkpoint inhibitor immunotherapy. He subsequently developed rapid in-field recurrence which was treated with salvage surgical resection and implantation of intracavitary cesium-131 brachytherapy. The patient's disease remained stable through 18 months postoperatively. This case illustrates the range of options available and provides a combination salvage therapy strategy in a select group of locally recurrent patients who have exhausted conventional treatment options.

The Stanford stereotactic radiosurgery experience on 7000 patients over 2 decades (1999-2018): looking far beyond the scalpel

OBJECTIVE

The CyberKnife (CK) has emerged as an effective frameless and noninvasive method for treating a myriad of neurosurgical conditions. Here, the authors conducted an extensive retrospective analysis and review of the literature to elucidate the trend for CK use in the management paradigm for common neurosurgical diseases at their institution.

METHODS

A literature review (January 1990-June 2019) and clinical review (January 1999-December 2018) were performed using, respectively, online research databases and the Stanford Research Repository of patients with intracranial and spinal lesions treated with CK at Stanford. For each disease considered, the coefficient of determination (r2) was estimated as a measure of CK utilization over time. A change in treatment modality was assessed using a t-test, with statistical significance assessed at the 0.05 alpha level.

RESULTS

In over 7000 patients treated with CK for various brain and spinal lesions over the past 20 years, a positive linear trend (r2 = 0.80) in the system's use was observed. CK gained prominence in the management of intracranial and spinal arteriovenous malformations (AVMs; r2 = 0.89 and 0.95, respectively); brain and spine metastases (r2 = 0.97 and 0.79, respectively); benign tumors such as meningioma (r2 = 0.85), vestibular schwannoma (r2 = 0.76), and glomus jugulare tumor (r2 = 0.89); glioblastoma (r2 = 0.54); and trigeminal neuralgia (r2 = 0.81). A statistically significant difference in the change in treatment modality to CK was observed in the management of intracranial and spinal AVMs (p < 0.05), and while the treatment of brain and spine metastases, meningioma, and glioblastoma trended toward the use of CK, the change in treatment modality for these lesions was not statistically significant.

CONCLUSIONS

Evidence suggests the robust use of CK for treating a wide range of neurological conditions.

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.

Whole-Brain Radiotherapy vs. Localized Radiotherapy after Resection of Brain Metastases in the Era of Targeted Therapy: A Retrospective Study

Simple Summary

The paradigm shift from cytotoxic chemotherapy to molecular targeted therapy dramatically improved the survival and quality of life of cancer patients. In radio-oncological aspects, there also was a paradigm shift from whole-brain radiotherapy to localized radiotherapy including stereotactic radiosurgery. This retrospective study analyzed 124 consecutive patients who had undergone surgical resection of brain metastases. We found targeted therapies to improve overall survival and distant control with decreased incidence of leptomeningeal metastasis. Our data suggest that localized radiotherapy is sufficient after resection of brain metastases when systemic targeted therapy is available.

Abstract

Whether targeted therapy (TT) and radiotherapy impact survival after resection of brain metastases (BM) is unknown. The purpose of this study was to analyze the factors affecting overall survival (OS), local control (LC), distant control (DC), and leptomeningeal metastases (LMM) in patients who had undergone resection of BM. We retrospectively analyzed 124 consecutive patients who had undergone resection of BM between 2004 and 2020. Patient information about age, sex, Karnofsky Performance Scale (KPS), origin of cancer, synchronicity, tumor size, status of primary cancer, use of TT, extent of resection, and postoperative radiotherapy was collected. Radiation therapy was categorized into whole-brain radiotherapy (WBRT), localized radiotherapy (local brain radiotherapy or stereotactic radiosurgery (LBRT/SRS)), and no radiation. We identified factors that affect OS, LC, DC, and LMM. In multivariable analysis, significant factors for OS were higher KPS score (≥90) (HR 0.53, p = 0.011), use of TT (HR 0.43, p = 0.001), controlled primary disease (HR 0.63, p = 0.047), and single BM (HR 0.55, p = 0.016). Significant factors for LC were gross total resection (HR 0.29, p = 0.014) and origin of cancer (p = 0.041). Both WBRT and LBRT/SRS showed superior LC than no radiation (HR 0.32, p = 0.034 and HR 0.38, p = 0.018, respectively). Significant factors for DC were use of TT (HR 0.54, p = 0.022) and single BM (HR 0.47, p = 0.004). Reduced incidence of LMM was associated with use of TT (HR 0.42, p = 0.038), synchronicity (HR 0.25, p = 0.028), and controlled primary cancer (HR 0.44, p = 0.047). TT was associated with prolonged OS, improved DC, and reduced LMM in resected BM patients. WBRT and LBRT/SRS showed similar benefits on LC. Considering the extended survival of cancer patients and the long-term effect of WBRT on cognitive function, LBRT/SRS appears to be a good option after resection of BM.

Internal dose escalation associated with increased local control for melanoma brain metastases treated with stereotactic radiosurgery

OBJECTIVE

The internal high-dose volume varies widely for a given prescribed dose during stereotactic radiosurgery (SRS) to treat brain metastases (BMs). This may be altered during treatment planning, and the authors have previously shown that this improves local control (LC) for non-small cell lung cancer BMs without increasing toxicity. Here, they seek to identify potentially actionable dosimetric predictors of LC after SRS for melanoma BM.

METHODS

The records of patients with unresected melanoma BM treated with single-fraction Gamma Knife RS between 2006 and 2017 were reviewed. LC was assessed on a per-lesion basis, defined as stability or a decrease in lesion size. Outcome-oriented approaches were utilized to determine optimal dichotomization for dosimetric variables relative to LC. Univariable and multivariable Cox regression analysis was implemented to evaluate the impact of collected parameters on LC.

RESULTS

Two hundred eighty-seven melanoma BMs in 79 patients were identified. The median age was 56 years (range 31-86 years). The median follow-up was 7.6 months (range 0.5-81.6 months), and the median survival was 9.3 months (range 1.3-81.6 months). Lesions were optimally stratified by volume receiving at least 30 Gy (V30) greater than or equal to versus less than 25%. V30 was ≥ and < 25% in 147 and 140 lesions, respectively. For all patients, 1-year LC was 83% versus 66% for V30 ≥ and < 25%, respectively (p = 0.001). Stratifying by volume, lesions 2 cm or less (n = 215) had 1-year LC of 82% versus 70% (p = 0.013) for V30 ≥ and < 25%, respectively. Lesions > 2 to 3 cm (n = 32) had 1-year LC of 100% versus 43% (p = 0.214) for V30 ≥ and < 25%, respectively. V30 was still predictive of LC even after controlling for the use of immunotherapy and targeted therapy. Radionecrosis occurred in 2.8% of lesions and was not significantly associated with V30.

CONCLUSIONS

For a given prescription dose, an increased internal high-dose volume, as indicated by measures such as V30 ≥ 25%, is associated with improved LC but not increased toxicity in single-fraction SRS for melanoma BM. Internal dose escalation is an independent predictor of improved LC even in patients receiving immunotherapy and/or targeted therapy. This represents a dosimetric parameter that is actionable at the time of treatment planning and warrants further evaluation.

Resection of isolated brain metastases in non-small cell lung cancer (NSCLC) patients - evaluation of outcome and prognostic factors: A retrospective multicenter study

BACKGROUND AND OBJECTIVES

Brain metastases occur in about 30% of all patients with non-small cell lung cancer (NSCLC). In selected patients, long-term survival can be achieved by resection of brain metastases. In this retrospective study, we investigate the prognosis of NSCLC patients with resected brain metastases and possible prognostic factors.

METHODS

In 119 patients with NSCLC and resected brain metastases, we report the following parameters: extent of resection, resection status, postoperative complications and overall survival (OS). We used the log-rank test to compare unadjusted survival probabilities and multivariable Cox regression to investigate potential prognostic factors with respect to OS.

RESULTS

A total of 146 brain metastases were resected in 119 patients. The median survival was 18.0 months. Postoperative cerebral radiotherapy was performed in 86% of patients. Patients with postoperative radiotherapy had significantly longer survival (median OS 20.2 vs. 9.0 months, p = 0.002). The presence of multiple brain metastases was a negative prognostic factor (median OS 13.5 vs. 19.5 months, p = 0.006). Survival of patients with extracerebral metastases of NSCLC was significantly shorter than in patients who had exclusively brain metastases (median OS 14.0 vs. 23.1 months, p = 0.005). Both of the latter factors were independent prognostic factors for worse outcome in multivariate analysis.

CONCLUSIONS

Based on these data, resection of solitary brain metastases in patients with NSCLC and controlled extracerebral tumor disease is safe and leads to an overall favorable outcome. Postoperative radiotherapy is recommended to improve prognosis.

A radiomics-based model for predicting local control of resected brain metastases receiving adjuvant SRS

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SRS has emerged as an alternative to WBRT for surgically resected brain metastases.

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Pre-therapy radiomic features are predictive of local control after cavity SRS.

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Radiomic features were superior to clinical features for predicting local control.

Purpose

Adjuvant radiosurgery to the cavities of surgically resected brain metastases provides excellent local tumor control while reducing the risk of deleterious cognitive decline associated with whole brain radiotherapy. A subset of these patients, however, will develop disease recurrence following radiosurgery. In this study, we sought to assess the predictive capability of radiomic-based models, as compared with standard clinical features, in predicting local tumor control.

Methods

We performed a retrospective chart review of patients treated with adjuvant radiosurgery for resected brain metastases at the “Institution” from 2009 to 2019. Shape, intensity and texture based radiomics features of the cavities were extracted from the pre-radiosurgery treatment planning MRI scans and trained using a gradient boosting technique with K-fold cross validation.

Results

In total, 71 cavities from 67 treated patients were included for analysis. The 6 and 12 month local control estimates were 86% and 76%, respectively. The 6 and 12 month overall survival was 78% and 55%, respectively. Thirty-six patients developed intracranial failures outside of the surgical cavity. The predictive model for local control trained on imaging features from the whole cavity achieved an area-under-the-curve (AUC) of 0.73 on the validation set versus an AUC of 0.40 for the clinical features.

Conclusions

Here we report a single institutional experience using radiomic-based predictive modeling of local tumor control following adjuvant Gamma Knife radiosurgery for resected brain metastases. We found the radiomics features to provide more robust predictive models of local control rates versus clinical features alone. Such techniques could potentially prove useful in the clinical setting and warrant further investigation.

Current status and recent advances in resection cavity irradiation of brain metastases

Despite complete surgical resection brain metastases are at significant risk of local recurrence without additional radiation therapy. Traditionally, the addition of postoperative whole brain radiotherapy (WBRT) has been considered the standard of care on the basis of randomized studies demonstrating its efficacy in reducing the risk of recurrence in the surgical bed as well as the incidence of new distant metastases. More recently, postoperative stereotactic radiosurgery (SRS) to the surgical bed has emerged as an effective and safe treatment option for resected brain metastases. Published randomized trials have demonstrated that postoperative SRS to the resection cavity provides superior local control compared to surgery alone, and significantly decreases the risk of neurocognitive decline compared to WBRT, without detrimental effects on survival. While studies support the use of postoperative SRS to the resection cavity as the standard of care after surgery, there are several issues that need to be investigated further with the aim of improving local control and reducing the risk of leptomeningeal disease and radiation necrosis, including the optimal dose prescription/fractionation, the timing of postoperative SRS treatment, and surgical cavity target delineation. We provide a clinical overview on current status and recent advances in resection cavity irradiation of brain metastases, focusing on relevant strategies that can improve local control and minimize the risk of radiation-induced toxicity.

Clinical outcome after CyberKnife® radiosurgery re-irradiation for recurrent brain metastases

PURPOSE

The objective of this study was to elucidate the impact on clinical outcomes resulting from re-irradiation for locally recurrent (LR) brain metastases (BM) using CyberKnife® stereotactic radiosurgery (SRS).

MATERIALS AND METHODS

Seventy-seven patients with 254 LR BM lesions treated using SRS re-irradiation between January 2014 and December 2018 were analysed in this retrospective study. The local control (LC), overall survival (OS) rates, and adverse events were assessed. The adverse events were classified according to the Common terminology for adverse event (CTCAE) v5.0.

RESULTS

The median follow-up duration was 8.9 months. The median age of the patients was 55 years (IQR: 47-62). The 3, 6, and 9-month LC and OS rates were 92.2%, 73.4%, and 73.4% and 79.2%, 61.0%, and 48.1%, respectively. On multivariate analysis the gender (male vs. female; HR, 1.79; 95% CI, 1.06-3.01; P=0.028), type of first brain radiation (WBI vs. SRS) followed by re-irradiation using SRS (HR, 9.32; 95% CI, 2.77-15.27; P<0.001) tumour volume (>12cc vs. ≤12cc; HR, 1.84; 95% CI, 1.10-3.11; P=0.02), and recursive partitioning analysis (RPA) (I vs. II & III; HR, 0.38; 95% CI, 0.19-0.70; P=0.001) were independent predictive factor for OS. Radionecrosis was reported in 3 patients.

CONCLUSION

With acceptable toxicity, SRS re-irradiation for LR BM showed a favourable rate for LC and OS and reported better OS for the female gender, a patient undergoing first brain radiation with SRS, tumour volume ≤12cc, and RPA-I. This result needs to be further evaluated in future clinical studies.

Local failure after stereotactic radiosurgery (SRS) for intracranial metastasis: analysis from a cooperative, prospective national registry

INTRODUCTION

Stereotactic radiosurgery (SRS) has been increasingly employed to treat patients with intracranial metastasis, both as a salvage treatment after failed whole brain radiation therapy (WBRT) and as an initial treatment. "Several studies have shown that SRS may be as effective as WBRT with the added benefit of preserving neuro-cognition". However, some patients may have local failure following SRS for intracranial metastasis, defined as increase in total lesion volume by 25% after at least 3 months of follow up.

METHODS

The SRS registry, established by the Neuro point alliance (NPA) under the auspices of the American Association of Neurological Surgeons (AANS), was queried for patients with intracranial metastasis receiving SRS at the participating sites. Demographic, clinical symptoms, tumor, and treatment characteristics as well as follow up status were summarized for the cohort. A multivariable explanatory cox- regression was performed to evaluate the impact of each of the factors on time to local failure.at last follow-up.

RESULTS

A total of 441 patients with 1255 intracranial metastatic lesions undergoing SRS were identified. The most common primary cancer histology was non-small cell lung cancer (43.8%, n = 193). More than half of the cohort had more than 1 metastatic lesion (2-3 lesions: 29.5%, n = 130; more than 3 lesions: 25.2% (n = 111). The average duration of follow-up for the cohort was found to be 8.4 months (SD = 7.61). The mean clinical treatment volume (CTV), after adding together the volume of each lesion for each patient was 5.39 cc (SD = 7.6) at baseline. A total of 20.2% (n = 89) had local failure (increase in volume by  > 25%) with a mean time to progression of 7.719 months (SD = 6.09). The progression free survival (PFS) for the cohort at 3, 6 and 12 months were found to be 94.9%, 84.3%, and 69.4%, respectively. On multivariable cox regression analysis, factors associated with increased hazard of local failure included male gender (HR 1.65, 95% CI 1.03-2.66, p = 0.037), chemotherapy at or before SRS (HR = 2.39, 95% CI 1.41-4.05, p = 0.001), WBRT at or before SRS (HR = 2.21, 95% CI 1.16- 4.22, p = 0.017), while surgical resection (HR 0.45, 95% CI 0.21-0. 97, p = 0.04) and immunotherapy (0.34, 95% CI 0.16-0.50, p = 0.014) were associated with lower hazard of local failure.

CONCLUSION

Factors found to be predictive of local failure included higher RPA score and those receiving chemotherapy, while patients undergoing surgical resection and those with occipital lobe lesions were less likely to experience local failure. Our analyses not only corroborate those previously reported but also demonstrate the utility of a multi-institutional registry to advance real-world SRS research for patients with intracranial metastatic lesions.

A Phase II Study of Neoadjuvant Stereotactic Radiosurgery for Large Brain Metastases: Clinical Trial Protocol

BACKGROUND

Brain metastases which require resection are treated with surgery followed by whole brain radiation therapy or postoperative cavity boost stereotactic radiosurgery (POCBS). Recently a novel strategy using neoadjuvant stereotactic radiosurgery (NaSRS) followed by resection was reported, demonstrating lower rates of postoperative leptomeningeal dissemination (LMD) and symptomatic radiation toxicity compared to a comparative cohort of patients treated with postoperative SRS.

OBJECTIVE

To determine if the rate of symptomatic radiation toxicity at 1 yr in patients who receive NaSRS differs significantly from historical rates for patients treated with POCBS.

METHODS

This is a multi-center, non-randomized, open phase II clinical trial. A total of 30 patients with up to 10 brain metastases, at least 1 of which is appropriate for surgical resection, will be enrolled for over 4 yr. All enrolled patients will be assigned to receive NaSRS followed by surgery.

EXPECTED OUTCOME

This study will clarify whether symptomatic radiation toxicity caused by NaSRS is significantly decreased compared to historical rates associated with POCBS. Secondary endpoints will include 1-yr local control (LC) of the treated lesion, 1-yr rates of LMD, median survival and 2-yr rates of progression-free and overall survival. Tertiary analyses will include correlation between LC and radiation toxicity with pretreatment clinical factors, serum markers, radiomic features, and molecular assessments of the resected tumors.

DISCUSSION

This prospective study will determine the toxicity associated with NaSRS and provide additional quantitative metrics of efficacy for future comparative trials.

Stereotactic Radiosurgery to Prevent Local Recurrence of Brain Metastasis After Surgery: Neoadjuvant Versus Adjuvant

Over the past 15-20 years, stereotactic radiosurgery (SRS) has become the dominant method for treating patients with brain metastases (BM). The role of surgery for management of large tumors also remains important. Combining these two treatment modalities may well achieve the best local control, safety, and symptomatic relief in cases of neoplasms for which resection is desirable. After 10 years of retrospective studies that suggested patients might do better if surgery were followed by early adjuvant SRS, a prospective, randomized, controlled trial was conducted to compare such treatment with postoperative observation after tumor removal, and it showed significantly better local control in the former cohort, especially in smaller lesions, but no difference in overall survival. On the other hand, in the past 5 years, some groups have argued that neoadjuvant SRS before resection of BM might be superior to adjuvant SRS, while no clinical trial has yet been concluded that compares these two treatment strategies. For now, adjuvant and neoadjuvant SRS show evidence of utility in achieving better local control after surgical removal of BM in comparison with surgery alone, but no specific guidelines exist favoring one method over the other, and both should be considered beneficial in clinical care.

Tumor Control Probability of Radiosurgery and Fractionated Stereotactic Radiosurgery for Brain Metastases

PURPOSE

As part of the American Association of Physicists in Medicine Working Group on Stereotactic Body Radiotherapy, tumor control probability (TCP) after stereotactic radiosurgery (SRS) and fractionated stereotactic radiosurgery (fSRS) for brain metastases was modeled based on pooled dosimetric and clinical data from published English-language literature.

METHODS AND MATERIALS

PubMed-indexed studies published between January 1995 and September 2017 were used to evaluate dosimetric and clinical predictors of TCP after SRS or fSRS for brain metastases. Eligible studies had ≥10 patients and included detailed dose-fractionation data with corresponding ≥1-year local control (LC) data, typically evaluated as a >20% increase in diameter of the targeted lesion using the pre-SRS diameter as a reference.

RESULTS

Of 2951 potentially eligible manuscripts, 56 included sufficient dose-volume data for analyses. Accepting that necrosis and pseudoprogression can complicate the assessment of LC, for tumors ≤20 mm, single-fraction doses of 18 and 24 Gy corresponded with >85% and 95% 1-year LC rates, respectively. For tumors 21 to 30 mm, an 18 Gy single-fraction dose was associated with 75% LC. For tumors 31 to 40 mm, a 15 Gy single-fraction dose yielded ∼69% LC. For 3- to 5-fraction fSRS using doses in the range of 27 to 35 Gy, 80% 1-year LC has been achieved for tumors of 21 to 40 mm in diameter.

CONCLUSIONS

TCP for SRS and fSRS are presented. For small lesions ≤20 mm, single doses of ≈18 Gy appear generally associated with excellent rates of LC; for melanoma, higher doses seem warranted. For larger lesions >20 mm, local control rates appear to be ≈ 70% to 75% with usual doses of 15 to 18 Gy, and in this setting, fSRS regimens should be considered. Greater consistency in reporting of dosimetric and LC data is needed to facilitate future pooled analyses. As systemic and biologic therapies evolve, updated analyses will be needed to further assess the necessity, efficacy, and toxicity of SRS and fSRS.

The Judicious Use of Stereotactic Radiosurgery and Hypofractionated Stereotactic Radiotherapy in the Management of Large Brain Metastases

Simple Summary

Brain metastases are the most common cause of cancerous brain tumors in adults. Large brain metastases are an especially difficult clinical scenario as patients often have debilitating symptoms from these tumors, and large tumors are more difficult to control with traditional single treatment radiation regimens alone or after surgery. Hypofractionated stereotactic radiotherapy is a novel way to deliver the higher doses of radiation to control large tumors either after surgery (most common), alone (common), or potentially before surgery (uncommon). Herein, we describe how delivering high doses over three or five treatments may improve tumor control and decrease complication rates compared to more traditional single treatment regimens for brain metastases larger than 2 cm in maximum dimension.

Abstract

Brain metastases are the most common intracranial malignant tumor in adults and are a cause of significant morbidity and mortality for cancer patients. Large brain metastases, defined as tumors with a maximum dimension >2 cm, present a unique clinical challenge for the delivery of stereotactic radiosurgery (SRS) as patients often present with neurologic symptoms that require expeditious treatment that must also be balanced against the potential consequences of surgery and radiation therapy—namely, leptomeningeal disease (LMD) and radionecrosis (RN). Hypofractionated stereotactic radiotherapy (HSRT) and pre-operative SRS have emerged as novel treatment techniques to help improve local control rates and reduce rates of RN and LMD for this patient population commonly managed with post-operative SRS. Recent literature suggests that pre-operative SRS can potentially half the risk of LMD compared to post-operative SRS and that HSRT can improve risk of RN to less than 10% while improving local control when meeting the appropriate goals for biologically effective dose (BED) and dose-volume constraints. We recommend a 3- or 5-fraction regimen in lieu of SRS delivering 15 Gy or less for large metastases or resection cavities. We provide a table comparing the BED of commonly used SRS and HSRT regimens, and provide an algorithm to help guide the management of these challenging clinical scenarios.

Multi-institutional Analysis of Prognostic Factors and Outcomes After Hypofractionated Stereotactic Radiotherapy to the Resection Cavity in Patients With Brain Metastases

IMPORTANCE

For brain metastases, the combination of neurosurgical resection and postoperative hypofractionated stereotactic radiotherapy (HSRT) is an emerging therapeutic approach preferred to the prior practice of postoperative whole-brain radiotherapy. However, mature large-scale outcome data are lacking.

OBJECTIVE

To evaluate outcomes and prognostic factors after HSRT to the resection cavity in patients with brain metastases.

DESIGN, SETTING, AND PARTICIPANTS

An international, multi-institutional cohort study was performed in 558 patients with resected brain metastases and postoperative HSRT treated between December 1, 2003, and October 31, 2019, in 1 of 6 participating centers. Exclusion criteria were prior cranial radiotherapy (including whole-brain radiotherapy) and early termination of treatment.

EXPOSURES

A median total dose of 30 Gy (range, 18-35 Gy) and a dose per fraction of 6 Gy (range, 5-10.7 Gy) were applied.

MAIN OUTCOMES AND MEASURES

The primary end points were overall survival, local control (LC), and the analysis of prognostic factors associated with overall survival and LC. Secondary end points included distant intracranial failure, distant progression, and the incidence of neurologic toxicity.

RESULTS

A total of 558 patients (mean [SD] age, 61 [0.50] years; 301 [53.9%] female) with 581 resected cavities were analyzed. The median follow-up was 12.3 months (interquartile range, 5.0-25.3 months). Overall survival was 65% at 1 year, 46% at 2 years, and 33% at 3 years, whereas LC was 84% at 1 year, 75% at 2 years, and 71% at 3 years. Radiation necrosis was present in 48 patients (8.6%) and leptomeningeal disease in 73 patients (13.1%). Neurologic toxic events according to the Common Terminology Criteria for Adverse Events grade 3 or higher occurred in 16 patients (2.8%) less than 6 months and 24 patients (4.1%) greater than 6 months after treatment. Multivariate analysis identified a Karnofsky Performance Status score of 80% or greater (hazard ratio [HR], 0.61; 95% CI, 0.46-0.82; P < .001), 22 to 33 days between resection and radiotherapy (HR, 1.50; 95% CI, 1.07-2.10; P = .02), and a controlled primary tumor (HR, 0.69; 95% CI, 0.52-0.90; P = .007) as prognostic factors associated with overall survival. For LC, a single brain metastasis (HR, 0.57; 95% CI, 0.35-0.93; P = .03) and a controlled primary tumor (HR, 0.59; 95% CI, 0.39-0.92; P = .02) were significant in the multivariate analysis.

CONCLUSIONS AND RELEVANCE

To date, this cohort study includes one of the largest series of patients with brain metastases and postoperative HSRT and appears to confirm an excellent risk-benefit profile of local HSRT to the resection cavity. Additional studies will help determine radiation dose-volume parameters and provide a better understanding of synergistic effects with systemic and immunotherapies.

Current Multimodality Treatments Against Brain Metastases from Renal Cell Carcinoma

Simple Summary

Brain metastasis (BM) is generally one of poor prognostic factors in patients with advanced renal cell carcinoma. However, because of longer control of extra-cranial disease by the recent introduction of molecular target therapy and immune checkpoint inhibitor, the incidence of BM has been recently increasing and to progress the treatment of BM is one of urgent medical unmet needs. Although the pivotal clinical trials usually excluded patients with BM, BM subgroup data from the prospective and retrospective series have been gradually accumulated. To select the appropriate strategy, individual patient and tumor characteristics (e.g., Karnofsky Performance Status (KPS), systemic cancer burden, the number/size/location of BM) are important information. Among the local treatments, the technology of stereotactic radiosurgery (SRT) has been especially advanced and its adaptation has been expanded. The combination of SRT with molecular target therapy and/or immune checkpoint inhibitor would be promising to further enhance the efficacy without increased toxicity.

Abstract

In patients with renal cell carcinoma, brain metastasis is generally one of the poor prognostic factors. However, the recent introduction of molecular target therapy and immune checkpoint inhibitor has remarkably advanced the systemic treatment of metastatic renal cell carcinoma and prolonged the patients’ survival. The pivotal clinical trials of those agents usually excluded patients with brain metastasis. The incidence of brain metastasis has been increasing in the actual clinical setting because of longer control of extra-cranial disease. Brain metastasis subgroup data from the prospective and retrospective series have been gradually accumulated about the risk classification of brain metastasis and the efficacy and safety of those new agents for brain metastasis. While the local treatment against brain metastasis includes neurosurgery, stereotactic radiosurgery, and conventional whole brain radiation therapy, the technology of stereotactic radiosurgery has been especially advanced, and the combination with systemic therapy such as molecular target therapy and immune checkpoint inhibitor is considered promising. This review summarizes recent progression of multimodality treatment of brain metastasis of renal cell carcinoma from literature data and explores the future direction of the treatment.

Stereotactic Radiosurgery After Resection of Brain Metastases: Changing Patterns of Care in the United States

OBJECTIVE

Management of symptomatic brain metastases often includes surgical resection with postoperative radiotherapy. Postoperative whole-brain radiotherapy (WBRT) improves intracranial control but detrimentally impacts quality of life and neurocognition. We sought to characterize the use in the United States of postoperative stereotactic radiosurgery (SRS), an evolving standard-of-care associated with reduced cognitive effects.

METHODS

With the MarketScan Commercial Claims and Encounters Database from 2007 to 2015, we identified patients aged 18-65 years treated with resection of a brain metastasis followed by SRS or WBRT within 60 days of surgery. Logistic regression estimated associations between co-variables (treatment year, age, sex, geographic region, place of service, insurance type, disease histology, comorbidity score, and median area household income and educational attainment) and SRS receipt.

RESULTS

Of 4007 patients included, 1506 (37.6%) received SRS and 2501 (62.4%) received WBRT. Postoperative SRS increased from 16.5% (2007-2008) to 56.8% (2014-2015). Patients residing in areas with a median household income or an educational attainment below 50th percentile were significantly less likely to receive SRS after controlling for treatment year and other demographic characteristics (P < 0.01). Factors associated with greater odds of receiving SRS included younger age, female sex, melanoma histology, Western region location, hospital-based facility, and high-deductible health plan enrollment (P < 0.05 for each).

CONCLUSIONS

Postoperative SRS for brain metastases has increased from 2007 to 2015, with the majority of patients now receiving SRS over WBRT. Patients in areas of lower socioeconomic class were less likely to receive SRS, warranting further investigation of barriers to SRS adoption.

Whole-Brain Radiation Therapy Versus Stereotactic Radiosurgery for Cerebral Metastases

Whole-brain radiation therapy (WBRT) was frequently used to treat brain metastases in the past. Stereotactic radiosurgery (SRS) is now generally preferred to WBRT for patients with limited brain metastases. SRS can also be used to treat extensive brain metastases (>10-15 metastases), and clinical trials are currently comparing WBRT with SRS for extensive disease. SRS may allow for an increased risk of radiation necrosis or leptomeningeal disease dissemination after treatment. Preoperative SRS and multifraction radiotherapy decrease the risk of these side effects and may soon become standard of care. Combining SRS with immune checkpoint inhibitors may improve patient outcomes.

A Dose-Response Model of Local Tumor Control Probability After Stereotactic Radiosurgery for Brain Metastases Resection Cavities

Purpose

Recent randomized controlled trials evaluating stereotactic surgery (SRS) for resected brain metastases question the high rates of local control previously reported in retrospective studies. Tumor control probability (TCP) models were developed to quantify the relationship between radiation dose and local control after SRS for resected brain metastases.

Methods and Materials

Patients with resected brain metastases treated with SRS were evaluated retrospectively. Melanoma, sarcoma, and renal cell carcinoma were considered radio-resistant histologies. The planning target volume (PTV) was the region of enhancement on T1 post-gadolinium magnetic resonance imaging plus a 2-mm uniform margin. The primary outcome was local recurrence, defined as tumor progression within the resection cavity. Cox regression evaluated predictors of local recurrence. Dose-volume histograms for the PTV were obtained from treatment plans and converted to 3-fraction equivalent doses (α/β = 12 Gy). TCP models evaluated local control at 1-year follow-up as a logistic function of dose-volume histogram data.

Results

Among 150 cavities, 41 (27.3%) were radio-resistant. The median PTV volume was 14.6 mL (range, 1.3-65.3). The median prescription was 21 Gy (range, 15-25) in 3 fractions (range, 1-5). Local control rates at 12 and 24 months were 86% and 82%. On Cox regression, larger cavities (PTV > 12 cm³) predicted increased risk of local recurrence (P = .03). TCP modeling demonstrated relationships between improved 1-year local control and higher radiation doses delivered to radio-resistant cavities. Maximum PTV doses of 30, 35, and 40 Gy predicted 78%, 89%, and 94% local control among all radio-resistant cavities, versus 69%, 79%, and 86% among larger radio-resistant cavities.

Conclusions

After SRS for resected brain metastases, larger cavities are at greater risk of local recurrence. TCP models suggests that higher radiation doses may improve local control among cavities of radio-resistant histology. Given maximum tolerated doses established for single-fraction SRS, fractionated regimens may be required to optimize local control in large radio-resistant cavities.

Post-operative stereotactic radiosurgery of brain metastases: A single-center retrospective review of clinical outcomes

Aim:

We sought to retrospectively report our outcomes using post-operative stereotactic radiosurgery (SRS)/stereotactic radiotherapy (SRT) in place of whole-brain radiation therapy (WBRT) following resection of brain metastases from our hospital-based community practice.

Materials and Methods:

A retrospective review of 23 patients who underwent post-operative SRS at our single institution from 2013 to 2017 was undertaken. Patient records, treatment plans and diagnostic images were reviewed. Local failure, distant intracranial failure and overall survival were studied. Categorical variables were analyzed using Fisher’s exact tests. Continuous variables were analyzed using Mann–Whitney tests. The Kaplan–Meier method was used to estimate survival times.

Results:

16 (70%) were single-fraction SRS, whereas the remaining 7 patients received a five-fraction treatment course. The median single-fraction dose was 16 Gy (range, 16–18). The median total dose for fractionated treatments was 25 Gy (range, 25–35). Overall survival at 6 and 12 months was 95 and 67%, respectively. Comparison of SRS versus SRT local control rates at 6 and 12 months revealed control rates of 92 and 78% versus 29 and 14%, respectively. Every patient with dural/pial involvement at the time of surgery had distant intracranial failure at the 12-month follow-up.

Findings:

Single-fraction frameless SRS proved to be an effective modality with excellent local control rates. However, the five-fraction SRT course was associated with an increased rate of local recurrence. Dural/pial involvement may portend a high risk for distant intracranial disease; therefore, it may be prudent to consider alternative approaches in these cases.

Current Treatment of Melanoma Brain Metastasis

OPINION STATEMENT

With greater understanding of underlying biology and development of effective BRAF-targeted therapy and immunotherapy, along with remarkable advances in local treatment such as stereotactic radiosurgery, melanoma brain metastasis (MBM) is witnessing continually improving outcome, with 1-year overall survival rate approaching 85%. Given disease complexity and myriad treatment options, all patients with MBM should ideally be evaluated in a multidisciplinary setting to allow an individualized treatment approach based on prognostic groups, molecular classification, number and size of brain metastasis, and performance status. With improving outcome, pendulum has now swayed to focus more on effective treatment modalities with minimal neurological toxicity while maintaining quality of life. Surgery is usually considered in symptomatic and large MBMs, while stereotactic radiosurgery considered in 1-4 lesions, and now also being explored for up to 15 brain metastases for improved local control. The role of whole brain radiotherapy is diminishing given its neurocognitive toxicities and is reserved for patients with diffuse brain involvement. Cytotoxic chemotherapy has largely been ineffective without evidence for survival benefit. Immune checkpoint inhibitors have become the cornerstone of management for melanoma brain metastasis with durable intracranial tumor control and excellent toxicity profile. For patients with asymptomatic MBMs, ipilimumab and nivolumab have shown intracranial response near 60% and provides comparable clinical benefit in MBMs as for extracranial metastases. For patients with driver BRAF mutation, BRAFi-/MEKi-targeted agents are proven to be effective in MBM with high rate intracranial responses (44-59%). However, the durability of intracranial responses induced by BRAFi/MEKi seems to be shorter than that of extracranial disease. Emerging data support novel combination of systemic therapy and stereotactic radiosurgery, which appears to be safe and effective; however, potential benefits and risks should be evaluated prospectively. Promising ongoing trials will further expand therapeutic evidence in MBM, and patients should be encouraged to participate in clinical trials.

Post-operative radiation therapy to the surgical cavity with standard fractionation in patients with brain metastases

The paradigm for post-operative cavity radiation therapy has shifted to more targeted, less morbid approaches. Single-fraction or hypofractionated radiation therapy is a common approach to treating the postoperative cavity but is associated with a local failure rate 20–40%. We employed an alternative treatment strategy involving fractionated partial brain radiation therapy to the surgical cavity. Patients with brain metastases who underwent radiation treatment 30–42 Gy in 3 Gy/fraction regimens to surgical cavity were retrospectively identified. The 6-month and 12-month freedom from local failure rates were 97.0% and 88.2%. Three patients (7%) experienced local failure at 4, 6, and 22 months. Of these, the histologies were colorectal adenocarcinoma (N = 1) and breast adenocarcinoma (N = 2). The 6-month and 12-month freedom from distant brain metastases rates were 74.1% and 68.8%, respectively, and the 6-month and 12-month overall survival rates were 84.9% and 64.3% respectively. The median overall survival was 39 months, and there were no events of late radionecrosis. Fractionated partial brain irradiation to the surgical cavity of resected brain metastases results in low rates of local failure. This strategy represents an alternative to SRS and WBRT.

Hemorrhagic and Cystic Brain Metastases Are Associated With an Increased Risk of Leptomeningeal Dissemination After Surgical Resection and Adjuvant Stereotactic Radiosurgery

BACKGROUND

Brain metastases (BM) treated with surgical resection and focal postoperative radiotherapy have been associated with an increased risk of subsequent leptomeningeal dissemination (LMD). BMs with hemorrhagic and/or cystic features contain less solid components and may therefore be at higher risk for tumor spillage during resection.

OBJECTIVE

To investigate the association between hemorrhagic and cystic BMs treated with surgical resection and stereotactic radiosurgery and the risk of LMD.

METHODS

One hundred thirty-four consecutive patients with a single resected BM treated with adjuvant stereotactic radiosurgery from 2008 to 2016 were identified. Intracranial outcomes including LMD were calculated using the cumulative incidence model with death as a competing risk. Univariable analysis and multivariable analysis were assessed using the Fine & Gray model. Overall survival was analyzed using the Kaplan-Meier method.

RESULTS

Median imaging follow-up was 14.2 mo (range 2.5-132 mo). Hemorrhagic and cystic features were present in 46 (34%) and 32 (24%) patients, respectively. The overall 12- and 24-mo cumulative incidence of LMD with death as a competing risk was 11.0 and 22.4%, respectively. On multivariable analysis, hemorrhagic features (hazard ratio [HR] 2.34, P = .015), cystic features (HR 2.34, P = .013), breast histology (HR 3.23, P = .016), and number of brain metastases >1 (HR 2.09, P = .032) were independently associated with increased risk of LMD.

CONCLUSION

Hemorrhagic and cystic features were independently associated with increased risk for postoperative LMD. Patients with BMs containing these intralesion features may benefit from alternative treatment strategies to mitigate this risk.

Image-Guided, Linac-Based, Surgical Cavity-Hypofractionated Stereotactic Radiotherapy in 5 Daily Fractions for Brain Metastases

BACKGROUND

Cavity stereotactic radiotherapy has emerged as a standard option following resection of brain metastases. However, the optimal approach with either single-fraction or hypofractionated stereotactic radiotherapy (HSRT) remains a significant question.

OBJECTIVE

To report outcomes for 5-fraction HSRT to the surgical cavity, based on contouring according to a recently reported international consensus guideline.

METHODS

Patients treated with cavity HSRT were identified from a prospective institutional database. Local brain control (LC), distant brain failure (DBF), leptomeningeal disease (LMD), and overall survival rates were determined. Univariate and multivariable analyses were performed on potential predictive factors.

RESULTS

One hundred thirty-seven cavities in 122 patients were treated at a median total dose of 30 Gy (range, 25-35 Gy). The median follow-up was 16 mo (range, 1-60 mo). Nonsmall cell lung cancer was the most common histology (44%), followed by breast cancer (21%). In 57% of surgical cavities, the preoperative tumor diameter was >3 cm. One-year LC, DBF, LMD, and overall survival rates were 84%, 45%, 22%, and 62%, respectively. Multivariable analyses identified colorectal (hazard ratio [HR] 4.1, P = .0066) and melanoma (HR 2.4, P = .012) metastases as predictors of local recurrence; preoperative tumor diameter >2 cm (HR 8.9, P = .012) and absence of targeted therapy (HR 4.4, P = .03) as predictors of DBF; and breast cancer histology (HR 2.1, P = .05) and subtotal resection (HR 2.6, P = .009) as predictors of LMD. Symptomatic radiation necrosis was observed in 7 patients (6%).

CONCLUSION

High rates of LC were observed following this 5-fraction HSRT regimen. Superiority as compared to single-fraction SRS requires a randomized trial.

Surgical bed stereotactic radiotherapy of brain metastases: Clinical outcome and predictors of local and distant brain failure

PURPOSE

To retrospectively analyze the outcomes of stereotactic radiotherapy (SRT) targeted at surgical bed of brain metastases (BM) and identify patterns of local/distant brain relapses (LR/DBR).

PATIENTS/METHODS

Seventy patients were treated with SRT between 2008-2017. Marginal dose prescription on the 70% isodose line depended on the maximal diameter of the target volume and range between 15-18Gy for single fraction radiosurgery and 23.1-26Gy in 3-5 fractions for fractionated SRT.

RESULTS

At 12 months, the overall survival (OS) was 69% [CI _95%=59%-81%]. At 6 and 12 months, the cumulative incidence functions (CIF) of local relapse were 4% [1%-13%] and 15% [8%-26%], respectively. According to univariate analysis, factors associated with LR were an initial volume larger than 7cc (hazard ratio: 4.6 [1.0-20.8], P=0.046) and a positive resection margin [hazard ratio: 3.6 [1.1-12.0], P=0.037. DBR occurred in 54.3% of patients with a median time of 8 months. None of the variables tested (histology, location or number of lesions) were found correlated with the DBR. Leptomeningeal disease occurred in 12.9% of cases. Salvage whole brain radiotherapy (WBRT) was required in 45.7% of patients and delayed by a median time of 9.6 months. Symptomatic radionecrosis (RN) occurred in 7.1%.

CONCLUSIONS

Adjuvant SRT was an effective and well-tolerated treatment to control the postoperative risk of recurrence of BM without compromising OS. Positive resection margins and large volumes were predictors factor of local relapse.

Nodular Leptomeningeal Disease-A Distinct Pattern of Recurrence After Postresection Stereotactic Radiosurgery for Brain Metastases: A Multi-institutional Study of Interobserver Reliability

PURPOSE

For brain metastases, surgical resection with postoperative stereotactic radiosurgery is an emerging standard of care. Postoperative cavity stereotactic radiosurgery is associated with a specific, underrecognized pattern of intracranial recurrence, herein termed nodular leptomeningeal disease (nLMD), which is distinct from classical leptomeningeal disease. We hypothesized that there is poor consensus regarding the definition of LMD, and that a formal, self-guided training module will improve interrater reliability (IRR) and validity in diagnosing LMD.

METHODS AND MATERIALS

Twenty-two physicians at 16 institutions, including 15 physicians with central nervous system expertise, completed a 2-phase survey that included magnetic resonance imaging and treatment information for 30 patients. In the "pretraining" phase, physicians labeled cases using 3 patterns of recurrence commonly reported in prospective studies: local recurrence (LR), distant parenchymal recurrence (DR), and LMD. After a self-directed training module, participating physicians completed the "posttraining" phase and relabeled the 30 cases using the 4 following labels: LR, DR, classical leptomeningeal disease, and nLMD.

RESULTS

IRR increased 34% after training (Fleiss' Kappa K = 0.41 to K = 0.55, P < .001). IRR increased most among non-central nervous system specialists (+58%, P < .001). Before training, IRR was lowest for LMD (K = 0.33). After training, IRR increased across all recurrence subgroups and increased most for LMD (+67%). After training, ≥27% of cases initially labeled LR or DR were later recognized as nLMD.

CONCLUSIONS

This study highlights the large degree of inconsistency among clinicians in recognizing nLMD. Our findings demonstrate that a brief self-guided training module distinguishing nLMD can significantly improve IRR across all patterns of recurrence, and particularly in nLMD. To optimize outcomes reporting, prospective trials in brain metastases should incorporate central imaging review and investigator training.

Highlights on the Management of Oligometastatic Disease

Purpose: The understanding of oligometastatic disease (OMD) is rapidly evolving and with this comes the ability to utilize a number of modalities that excel in the localized control of disease. It has been identified that there are no clear guidelines based on high-level evidence to standardized approaches toward the management of OMD. These highlights have been developed to provide a road map for all health-care professionals who are involved in the management of OMD to support standardized patient care. Methods: The Saudi Lung Cancer Guidelines Committee is a part of the Saudi Lung Cancer Association which, in turn, is part of the Saudi Thoracic Society. Considering that lung cancer constitutes a major proportion of OMD prevalence, the committee took the initiative to develop national highlights to support the management of OMD within Saudi Arabia. The committee members are national clinical leaders who collaborated with international expertise to establish these highlights to serve as a general clinical pathway in the management of OMD. Results: Standardization of the indications to diagnose oligometastases and patient selection criteria including ineligibility criteria for treatment are the basis of the highlights. Treatment approaches including surgical and the variety of radiotherapeutical options are discussed in relation to specific oligometastatic sites. Acceptable measurements for response to treatment and the future for the treatment of OMD conclude the development of the highlights. Conclusion: These are the first national highlights addressing this important disease in oncology. The implementation of these highlights as guidelines requires a robust multidisciplinary team and access to specific technology and expertise. These highlights are based on the most recent findings within the literature but will require repeated review and updating due to this rapidly evolving field in disease management.

Comparison of Local Control of Brain Metastases With Stereotactic Radiosurgery vs Surgical Resection: A Secondary Analysis of a Randomized Clinical Trial

Importance

Brain metastases are a common source of morbidity for patients with cancer, and limited data exist to support the local therapeutic choice between surgical resection and stereotactic radiosurgery (SRS).

Objective

To evaluate local control of brain metastases among patients treated with SRS vs surgical resection within the European Organization for the Research and Treatment of Cancer (EORTC) 22952-26001 phase 3 trial.

Design, Setting, and Participants

This unplanned, exploratory analysis of the international, multi-institutional randomized clinical trial EORTC 22952-26001 (conducted from 1996-2007) was performed from February 9, 2017, through July 25, 2018. The EORTC 22952-26001 trial randomized patients with 1 to 3 brain metastases to whole-brain radiotherapy vs observation after complete surgical resection or before SRS. Patients in the present analysis were stratified but not randomized according to local modality (SRS or surgical resection) and treated per protocol with 1 to 2 brain metastases and tumors with a diameter of no greater than 4 cm.

Interventions

Surgical resection or SRS.

Main Outcomes and Measures

The primary end point was local recurrence of treated lesions. Cumulative incidence of local recurrence was calculated according to modality (surgical resection vs SRS) with competing risk regression to adjust for prognostic factors and competing risk of death.

Results

A total of 268 patients were included in the analysis (66.4% men; median age, 60.7 years [range, 26.9-81.1 years]); 154 (57.5%) underwent SRS and 114 (42.5%) underwent surgical resection. Median follow-up time was 39.9 months (range, 26.0-1982.0 months). Compared with the SRS group, patients undergoing surgical resection had larger metastases (median 28 mm [range, 10-40 mm] vs 20 mm [range, 4-40 mm]; P < .001), more frequently had 1 brain metastasis (112 [98.2%] vs 114 [74.0%]; P < .001), and differed in location (parietal, 21 [18.4%] vs 61 [39.6%]; posterior fossa, 30 [26.3%] vs 12 [7.8%]; P < .001). In adjusted models, local recurrence was similar between the SRS and surgical resection groups (hazard ratio [HR], 1.15; 95% CI, 0.72-1.83). However, when stratified by interval, patients with surgical resection had a much higher risk of early (0-3 months) local recurrence compared with those undergoing SRS (HR, 5.94; 95% CI, 1.72-20.45), but their risk decreased with time (HR for 3-6 months, 1.37 [95% CI, 0.64-2.90]; HR for 6-9 months, 0.75 [95% CI, 0.28-2.00]). At 9 months or longer, the surgical resection group had a lower risk of local recurrence (HR, 0.36; 95% CI, 0.14-0.93).

Conclusions and Relevance

In this exploratory analysis, local control of brain metastases was similar between SRS and surgical resection groups. Stereotactic radiosurgery was associated with improved early local control of treated lesions compared with surgical resection, although the relative benefit decreased with time.

Trial Registration

ClinicalTrials.gov Identifier: NCT00002899.

Predictors of radiation necrosis in long-term survivors after Gamma Knife stereotactic radiosurgery for brain metastases

Background

The long-term risk of necrosis after radiosurgery for brain metastases is uncertain. We aimed to investigate incidence and predictors of radiation necrosis for individuals with more than 1 year of survival after radiosurgery for brain metastases.

Methods

Patients who had a diagnosis of brain metastases treated between December 2006 and December 2014, who had at least 1 year of survival after first radiosurgery were retrospectively reviewed. Survival was analyzed using the Kaplan-Meier estimator, and the incidence of radiation necrosis was estimated with death or surgical resection as competing risks. Patient and treatment factors associated with radiation necrosis were also analyzed.

Results

A total of 198 patients with 732 lesions were analyzed. Thirty-four lesions required salvage radiosurgery and 10 required salvage surgical resection. Median follow-up was 24 months. The estimated median survival for this population was 25.4 months. The estimated per-lesion incidence of radiation necrosis at 4 years was 6.8%. Medical or surgical therapy was required for 60% of necrosis events. Tumor volume and male sex were significant factors associated with radiation necrosis. The per-lesions incidence of necrosis for patients undergoing repeat radiosurgery was 33.3% at 4 years.

Conclusions

In this large series of patients undergoing radiosurgery for brain metastases, patients continued to be at risk for radiation necrosis throughout their first 4 years of survival. Repeat radiosurgery of recurrent lesions greatly exacerbates the risk of radiation necrosis, whereas treatment of larger target volumes increases the risk modestly.