Gamma knife treatment of brainstem metastases

Efficacy and safety of a "sandwich therapy" based on staged stereotactic radiosurgery and bevacizumab for large brainstem metastases

OBJECTIVE

Gamma Knife stereotactic radiosurgery (SRS) is an effective therapeutic option for unresectable brainstem metastases. Currently, staged stereotactic radiosurgery (SSRS) has become available for large brainstem metastases（≥ 1 cm3） despite the limitation of peritumoral edema. The authors developed the so-called "sandwich therapy" which integrated 2-stage stereotactic radiosurgery (2-SSRS) with bevacizumab for peritumoral edema reduction and local control of large brainstem metastases.

METHODS

42 patients with large brainstem metastases ≥1 cm3 who received 2-SSRS simultaneously with bevacizumab were screened from 2019 to 2021 retrospectively. The first SRS margin doses were 13 Gy (range 11-15) and the second SRS margin doses were 12 Gy (range 11-13), one-time vascular endothelial growth factor (VEGF) inhibitor (bevacizumab) of 3.5-5 mg/kg was administrated intravenously the next day after the first SRS. The median interval between the two sessions of SRS was 6 days. Baseline demographics, clinical and radiology imaging follow-ups were recorded to determine symptomatic improvement, peritumoral edema reduction, local control, and disease progression. Median survival was calculated using Kaplan-Meier analysis. Multivariate analysis was performed to identify prognostic factors.

RESULTS

The "sandwich therapy" was applied to 42 lesions. Significant reductions of tumor volume (p < 0.05) and peritumoral edema volume (p < 0.01) were achieved at the second SRS in comparison to those at the first SRS. The proportion of favorable Karnofsky performance scale (KPS) (≥80 %) increased significantly at early follow-up time points and reached the highest value of 85.7 %. The median survival time was 9.7 months, the median local control duration was 11.3 months. 8 acute adverse events of CTCAE grade 2 and 3 were observed in 6 patients and resolved with palliative treatment. Tyrosine kinase inhibitor (TKI) treatment was identified as a predictive factor for longer survival.

CONCLUSION

The "sandwich therapy" which integrates 2-SSRS with bevacizumab is a safe and effective option for large brainstem metastases.

Brainstem Metastases Treated with Stereotactic Radiosurgery: Masked versus Framed Immobilization

BACKGROUND

Patients with brainstem metastases (BSMs) have minimal surgical options due to high-risk anatomy. To review our efficacy treating BSM using Gamma Knife stereotactic radiosurgery (SRS), we compared results on the basis of the utilization of mask-fixation (MF) or frame-fixation (FF).

METHODS

Data were retrospectively collected for 32 patients. Follow-up data for 49 lesions were analyzed for local control rate (LCR) and objective response rate (ORR).

RESULTS

Primary cancers included lung, breast, and melanoma; most lesions were pontine. MF was used in 18 patients. Average tumor volume was 0.99 cm3 (0.005-13.3 cm3). Thirty-nine lesions were treated with single-fraction 16 Gy. Ten lesions were treated in 3-5 fractions with mean dose of 22.5 Gy. Mean follow-up was 14.2 months (1.2-48.2 months). One-year LCR was 94.7%. ORR at last follow-up did not differ between MF and FF (P = 0.81). Average reduction of lesion volume at 6 and 12 months did not differ between MF and FF (64% vs. 45%, P = 0.77; 70% vs. 77%, P = 0.78). Failure occurred in a pontine colorectal cancer metastasis mask-immobilized for treatment with 14 Gy.

CONCLUSIONS

SRS for BSM achieved high LCR despite variability in tumor size and histology with no significant difference between MF and FF. Although trials have historically excluded patients with BSM, our data support SRS as a safe and efficacious treatment. This is the first study showing that MF provides equivalent, successful outcomes when compared with FF for patients with BSM.

Stereotactic radiosurgery for the treatment of brainstem metastases: a multicenter retrospective study

Background

Brainstem metastases (BSM) are associated with a poor prognosis and their management represents a therapeutic challenge. BSM are often inoperable and, in absence of randomized trials, the optimal radiation treatment of BSM remains to be defined. We evaluated the efficacy and toxicity of linear accelerator (linac)-based stereotactic radiosurgery (SRS) and hypofractionated steretotactic radiotherapy (HSRT) in the treatment of BSM in a series of patients treated in different clinical centers.

Methods

We conducted a multicentric retrospective study of patients affected by 1–2 BSM from different histologies who underwent SRS/HSRT. Freedom from local progression (FLP), cancer-specific survival (CSS), overall survival (OS), and treatment-related toxicity were evaluated. In addition, predictors of treatment response and survivals were evaluated.

Results

Between 2008 and 2021, 105 consecutive patients with 111 BMS who received SRS or HSRT for 1–2 BSM were evaluated. Median follow-up time was 10 months (range 3–130). One-year FLP rate was 90.4%. At the univariate analysis, tumor volume ≤ 0.4 cc, and concurrent targeted therapy were associated with longer FLP, with combined treatment that remained a significant independent predictor [0.058, HR 0.139 (95% CI 0.0182–1.064]. Median OS and CSS were 11 months and 14.6 months, respectively. At multivariate analysis, concurrent targeted therapy administration was significantly associated with longer OS [HR 0.514 (95%CI 0.302–0.875); p = 0.01]. Neurological death occurred in 30.4% of patients, although this was due to local progression in only 3 (2.8%) patients.

Conclusion

Linac-based SRS/HSRT offers excellent local control to patients with BSM, with low treatment-related toxicity and no apparent detrimental effects on OS. When treated with ablative intent, BSM are an uncommon cause of neurological death. The present results indicates that patients with BSM should not be excluded a priori from clinical trials.

Efficacy and Safety of Stereotactic Radiosurgery for Brainstem Metastases: A Systematic Review and Meta-analysis

Importance

Owing to the proximity to critical neurologic structures, treatment options for brainstem metastases (BSM) are limited, and BSM growth can cause acute morbidity or death. Stereotactic radiosurgery (SRS) is the only local therapy for BSM, but efficacy and safety of this approach are incompletely understood because patients with BSM are excluded from most clinical trials.

Objective

To perform a systematic review and comparative meta-analysis of SRS studies for BSM in the context of prospective trials of SRS or molecular therapy for nonbrainstem brain metastases (BM).

Data Sources

A comprehensive search of Pubmed/MEDLINE and Embase was performed on December 6, 2019.

Study Selection

English-language studies of SRS for BSM with at least 10 patients and reporting 1 or more outcomes of interest were included. Duplicate studies or studies with overlapping data sets were excluded. Studies were independently evaluated by 2 reviewers, and discrepancies were resolved by consensus. A total of 32 retrospective studies published between 1999 and 2019 were included in the analysis.

Data Extraction and Synthesis

Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines were followed to identify studies. Study quality was assessed using Methodological Index for Non-Randomized Studies criteria. Fixed and random-effects meta-analyses and meta-regressions were performed for the outcomes of interest.

Main Outcomes and Measures

Primary study outcomes included 1-year and 2-year local control and overall survival, objective response rate, symptom response rate, neurological death rate, and rate of grade 3 to 5 toxic effects as described in Common Terminology Criteria for Adverse Events, version 4.0.

Results

The 32 retrospective studies included in the analysis comprised 1446 patients with 1590 BSM that were treated with SRS (median [range] dose, 16 [11-39] Gy; median [range] fractions, 1 [1-13]). Local control at 1 year was 86% (95% CI, 83%-88%; I2 = 38%) in 1410 patients across 31 studies, objective response rate was 59% (95% CI, 47%-71%; I2 = 88%) in 642 patients across 17 studies, and symptom improvement was 55% (95% CI, 47%-63%; I2 = 41%) in 323 patients across 13 studies. Deaths from BSM progression after SRS were rare (19 of 703 [2.7%] deaths across 19 studies), and the neurologic death rate in patients with BSM (24%; 95% CI, 19%-31%; I2 = 62%) was equivalent to the neurologic death rate in patients with BM who were treated on prospective trials. The rate of treatment-related grade 3 to 5 toxic effects was 2.4% (95% CI, 1.5%-3.7%; I2 = 33%) in 1421 patients across 31 studies. These results compared favorably to trials of targeted or immunotherapy for BM, which had a wide objective response rate range from 17% to 56%.

Conclusions and Relevance

Results of this systematic review and meta-analysis show that SRS for BSM was associated with effectiveness and safety and was comparable to SRS for nonbrainstem BM, suggesting that patients with BSM should be eligible for clinical trials of SRS. In this analysis, patients treated with SRS for BSM rarely died from BSM progression and often experienced symptomatic improvement. Given the apparent safety and efficacy of SRS for BSM in the context of acute morbidity or death from BSM growth, consideration of SRS at the time of enrollment on emerging trials of targeted therapy for BM should be considered.

Clinical and radiographic adverse events after Gamma Knife radiosurgery for brainstem lesions: A dosimetric analysis

OBJECTIVES

To analyze the association between dosvolume relationships and adverse events in brainstem lesions treated with Gamma Knife radiosurgery (GKRS).

METHODS

Treatment plans were generated on BrainLab Elements and GammaPlan software. Dosimetric data were analyzed as continuous variables for patients who received GKRS to brain metastases or arteriovenous malformations (AVM) within or abutting the brainstem. Adverse events were classified as clinical and/or radiographic. Logistic and cox regression were used to assess the relationship between dosimetric variables and adverse events.

RESULTS

Sixty-one patients who underwent single fraction GKRS for brain metastases or AVM were retrospectively analyzed. Median age was 62 years (range: 12-92 years) and the median prescription dose was 18 Gy (range: 13-25 Gy). Median follow-up was 6months. Clinical and radiographic complications were seen in ten (16.4%) and 17 (27.9%) patients, respectively. On logistic regression, increasing D_05% was found to be associated with an increased probability of developing a clinical complication post-GKRS (OR: 1.18; 95% CI: 1.01-1.39; p = 0.04). Furthermore, mean brainstem dose (HR: 1.43; 95% CI: 1.05-1.94; p < 0.02), D_05% (HR: 1.09; 95% CI: 1.01-1.18; p = 0.03), and D_95% (HR: 2.37; 95% CI: 0.99-5.67; p = 0.05) were associated with an increased hazard of experiencing post-GKRS complications over time.

CONCLUSIONS

Increasing D_05% to the brainstem is associated with an increased risk of developing clinical complications. Clinicians may consider this parameter in addition to fractionated stereotactic radiation therapy when well-established dose constraints are not met in this patient population. Additional data are needed to further validate these findings.

Adaptive hypofractionated gamma knife radiosurgery in the acute management of brainstem metastases

Background:

Intrinsic brainstem metastases are life-threatening neoplasms requiring rapid, effective intervention. Microsurgery is considered not feasible in most cases and systemic treatment seldom provides a successful outcome. In this context, radiation therapy remains the best option but adverse radiation effects (ARE) remain a major concern. A dose-adaptive gamma knife procedure coined as Rapid Rescue Radiosurgery (3R) offers the possibility to treat these lesions whilst reducing the risk of ARE evolvement. We report the results of 3R applied to a group of patients with brainstem metastases.

Methods:

Eight patients with nine brainstem metastases, having undergone three separate, dose-adapted gamma knife radiosurgery (GKRS) procedures over 7 days, were retrospectively analyzed in terms of tumor volume reduction, local control rates, and ARE-development under the period of treatment and at least 6 months after treatment completion.

Results:

Mean peripheral doses at GKRS 1, GKRS 2, and GKRS 3 were 7.4, 7.7, and 8.2 Gy (range 6–9 Gy) set at the 35–50% isodose lines. Mean tumor volume reduction between GKRS 1 and GKRS 3 was −15% and −56% at first follow-up. Four patients developed radiologic signs of ARE but remained clinically asymptomatic. One patient developed a local recurrence at 34 months. Mean survival from GKRS 1 was 13 months. Two patients were still alive at the time of paper submission (10 and 23 months from GKRS 1).

Conclusions:

In this study, 3R proved effective in terms of tumor volume reduction, rescue/preservation of neurological function, and limited ARE evolvement.

Toxicity of Radiosurgery for Brainstem Metastases

BACKGROUND

Although stereotactic radiosurgery (SRS) is an effective modality in the treatment of brainstem metastases (BSM), radiation-induced toxicity remains a critical concern. To better understand how severe or life-threatening toxicity is affected by the location of lesions treated in the brainstem, a review of all available studies reporting SRS treatment for BSM was performed.

METHODS

Twenty-nine retrospective studies investigating SRS for BSM were reviewed.

RESULTS

The rates of grade 3 or greater toxicity, based on the Common Terminology Criteria for Adverse Events, varied from 0 to 9.5% (mean 3.4 ± 2.9%). Overall, the median time to toxicity after SRS was 3 months, with 90% of toxicities occurring before 9 months. A total of 1243 cases had toxicity and location data available. Toxicity rates for lesions located in the medulla were 0.8% (1/131), compared with midbrain and pons, respectively, 2.8% (8/288) and 3.0% (24/811).

CONCLUSIONS

Current data suggest that brainstem substructure location does not predict for toxicity and lesion volume within this cohort with median tumor volumes 0.04-2.8 cc does not predict for toxicity.

Brainstem metastases treated with Gamma Knife stereotactic radiosurgery: the Indiana University Health experience

Brainstem metastases offer a unique challenge in cancer treatment, yet stereotactic radiosurgery (SRS) has proven to be an effective modality in treating these tumors. This report discusses the clinical outcomes of patients with brainstem metastases treated at Indiana University with Gamma Knife (GK) radiosurgery from 2008 to 2016. 19 brainstem metastases from 14 patients who had follow-up brain imaging were identified. Median tumor volume was 0.04 cc (range: 0.01–2.0 cc). Median prescribed dose was 17.5 Gy to the 50% isodose line (range: 14–22 Gy). Median survival after GK SRS treatment to brainstem lesion was 17.2 months (range: 2.8–45.6 months). The experience at Indiana University confirms the safety and efficacy of range of GK SRS prescription doses (14–22 Gy) to brainstem metastases.

[Experience with the radiosurgical treatment of brain metastases]

OBJECTIVE

To analyse the survival rate of a cohort of patients with intracranial metastases treated with radiosurgery, and to determine the factors that influence the results.

PATIENTS AND METHOD

Retrospective analysis performed on a cohort of 126 patients undergoing radiosurgery for brain metastases. Patients treated with surgery before or after radiosurgery were excluded. Survival is analysed based on clinical (age, sex, primary tumour), radiological (number, location and volume of lesions), and radiotherapy factors (treatment dose, holocraneal radiation). Univariate and multivariate analyses were performed to determine significant prognostic factors.

RESULTS

A total of 225 brain metastases in 126 patients, with a mean age of 59.8±11.6years, were treated between February 2008 and April 2015. The mean survival was 8.2 months. The overall survival rates at 6months, 1year, and 2years were 60.3%, 31.5%, and 12.8%, respectively. Lung (59.5%) and breast (14.3) were the most common primary tumours, and the most common site for metastases was the cerebral hemisphere (77%) and the average volume was 10.35 cc (0.2-43.5). Significant survival factors were: age under 60 (P=.046), female (P<.001), breast cancer (P<.001), KPS >80 (P=.001), SIR6 >5 (P=.031), and GPA ≥2.5 (P=.003).

CONCLUSIONS

Radiosurgery is an appropriate technique for the treatment of brain metastases, and the main prognostic factors include being age under 65, female, breast cancer, and good scores on Karnofsky, SIR, and GPA scales.

Stereotactic Radiosurgery for Brainstem Metastases: An International Cooperative Study to Define Response and Toxicity

PURPOSE

To pool data across multiple institutions internationally and report on the cumulative experience of brainstem stereotactic radiosurgery (SRS).

METHODS AND MATERIALS

Data on patients with brainstem metastases treated with SRS were collected through the International Gamma Knife Research Foundation. Clinical, radiographic, and dosimetric characteristics were compared for factors prognostic for local control (LC) and overall survival (OS) using univariate and multivariate analyses.

RESULTS

Of 547 patients with 596 brainstem metastases treated with SRS, treatment of 7.4% of tumors resulted in severe SRS-induced toxicity (grade ≥3, increased odds with increasing tumor volume, margin dose, and whole-brain irradiation). Local control at 12 months after SRS was 81.8% and was improved with increasing margin dose and maximum dose. Overall survival at 12 months after SRS was 32.7% and impacted by age, gender, number of metastases, tumor histology, and performance score.

CONCLUSIONS

Our study provides additional evidence that SRS has become an option for patients with brainstem metastases, with an excellent benefit-to-risk ratio in the hands of experienced clinicians. Prior whole-brain irradiation increases the risk of severe toxicity in brainstem metastasis patients undergoing SRS.

Adaptive hypofractionated gamma knife radiosurgery for a large brainstem metastasis

Background:

To demonstrate how adaptive hypofractionated radiosurgery by gamma knife (GK) can be successfully utilized to treat a large brainstem metastasis - a novel approach to a challenging clinical situation.

Case Description:

A 42-year-old woman, diagnosed with metastatic nonsmall cell lung cancer in July 2011, initially treated with chemotherapy and tyrosine kinase inhibitors, developed multiple brain metastases March 2013, with subsequent whole brain radiotherapy, after which a magnetic resonance imaging (MRI) showed a significant volume regression of all brain metastases. A follow-up MRI in October 2013 revealed a growing brainstem lesion of 26 mm. Linear accelerator-based radiotherapy and microsurgery were judged contraindicated, why the decision was made to treat the patient with three separate radiosurgical sessions during the course of 1 week, with an 18% tumor volume reduction demonstrated after the last treatment. Follow-up MRI 2.5 months after her radiosurgical treatment showed a tumor volume reduction of 67% compared to the 1^st day of treatment. Later on, the patient developed a radiation-induced perilesional edema although without major clinical implications. An MRI at 12 months and 18-fluoro-deoxyglucose positron emission tomography of the brain at 13 months showed decreased edema with no signs of tumor recurrence. Despite disease progression during the last months of her life, the patient's condition remained overall acceptable.

Conclusion:

GK-based stereotactic adaptive hypofractionation proved to be effective to achieve tumor control while limiting local adverse reactions. This surgical modality should be considered when managing larger brain lesions in critical areas.

How Does Brainstem Involvement Affect Prognosis in Patients with Limited Brain Metastases? Results of a Matched-Cohort Analysis

OBJECTIVE

Although brainstem metastases are thought to portend an inferior prognosis compared to non-brainstem brain metastases, there is limited evidence to support this claim, particularly in the modern radiosurgical era.

METHODS

We collected the clinical data for 500 patients with brain metastases treated at our institution with stereotactic radiosurgery (SRS). All patients received SRS to at least one brain metastasis, and all brainstem metastases underwent SRS. After propensity score matching, clinical characteristics and overall survival were calculated and compared between groups.

RESULTS

Three hundred sixteen patients with brain metastases were analyzed after matching (143 with brainstem involvement and 173 without). Patients with brainstem metastases lived shorter after first SRS than patients without brainstem metastases did (median 4.4 and 6.5 months, respectively; P = 0.01), and they were more likely to have received whole brain irradiation (P = 0.003). Patients with a single metastasis did not survive longer than patients with multiple brain metastases if there was brainstem involvement (P = 0.45). The incidence of new extracranial disease and severe toxicity after SRS did not differ between groups.

CONCLUSIONS

The survival of patients with brain metastases is inferior after a metastatic lesion develops within the brainstem, despite favorable local control with brainstem SRS. The brainstem location should be considered a negative prognostic factor for survival after SRS, and it could result from the eloquence of this location. Future research could identify the clinically life-limiting component of brainstem metastases.

Brainstem metastases treated with stereotactic radiosurgery: safety, efficacy, and dose response

The safety and efficacy of stereotactic radiosurgery (SRS) in the brainstem is questioned by some over concern of violating historical brainstem SRS dose tolerance. Our purpose was to report on the clinical outcomes of patients treated at our institution with radiosurgery for brainstem metastases. Patients with metastatic tumors within or directly abutting the brainstem from 1992 to 2014 were analyzed. Patient and tumor characteristics, SRS parameters, and toxicity were recorded and analyzed for associations with local control and survival. Multivariate statistical analysis was performed using Cox proportional hazards modeling. One-hundred and eighty-nine (189) brainstem metastases from 161 patients were included in our analysis. Whole brain irradiation was administered prior to SRS in 52 % of patients. The median margin dose was 18 Gy prescribed to the 50 % isodose line. Median imaging follow up was 5.4 months and median survival was 5.5 months after SRS. At last follow up, local control was achieved in 87.3 % of brainstem lesions treated. There were 3 recorded events of grade 3-5 toxicity (1.8 %). On multivariate analysis, a margin dose ≥16 Gy was associated with improved local control (p = 0.049) and greater KPS score was associated with improved overall survival following SRS (p = 0.024). Patients with brainstem metastases who have limited intracranial disease and/or who have received whole brain irradiation should be considered for SRS. Margin doses of at least 16 Gy are associated with superior local control, and serious radiation toxicity in SRS for brainstem metastasis appears rare.

Brain metastases: an overview

So far brain metastases represent a critical stage of a disease course and the frequency is increasing over the years. The treatment of brain metastases should be individualized for each patient: in case of single brain metastasis, surgery or radiosurgery should be considered as first options of treatment; in case of multiple lesions, whole-brain radiotherapy is the standard of care in association with systemic therapy or surgery/radiosurgery. Chemotherapy should be considered when surgery or radiation therapy are not possible. In the last decades, TKIs or monoclonal antibodies have shown increase in overall response rate and overall survival in Phase II-III trials. The aim of this paper is to make an overview of the current approaches in management of patients with brain metastases.

Stereotactic aspiration combined with gamma knife radiosurgery for the treatment of cystic brainstem metastasis originating from lung adenosquamous carcinoma: A case report

Brainstem metastases have a poor prognosis and are difficult to manage. The present study describes the first case of histopathologically-confirmed brainstem metastasis originating from lung adenosquamous carcinoma, and discusses the outcomes of treatment by stereotactic aspiration combined with gamma knife radiosurgery (GKRS). A 59-year-old female presented with a cystic mass (15×12×13 mm; volume, 1.3 cm³) located in the pons, two years following surgical treatment for adenosquamous carcinoma of the lung. The patient received initial GKRS for the lesion in the pons with a total dose of 54.0 Gy, however, the volume of the mass subsequently increased to 3.9 cm³ over a period of three months. Computed tomography-guided stereotactic biopsy and aspiration of the intratumoral cyst were performed, yielding 2.0 cm³ of yellow-white fluid. Histology confirmed the diagnosis of adenosquamous carcinoma. Aspiration provided immediate symptomatic relief, and was followed one week later by repeat GKRS with a dose of 12.0 Gy. The patient survived for 12 months following the repeat GKRS; however, later succumbed to the disease after lapsing into a two-week coma. The findings of this case suggest that stereotactic aspiration of cysts may improve the effects of GKRS for the treatment of cystic brainstem metastasis; the decrease in tumor volume allowed a higher radiation dose to be administered with a lower risk of radiation-induced side effects. Therefore, stereotactic aspiration combined with GKRS may be an effective treatment for brainstem metastasis originating from adenosquamous carcinoma.