Comparing pre-operative stereotactic radiosurgery (SRS) to post-operative whole brain radiation therapy (WBRT) for resectable brain metastases: a multi-institutional analysis

Preoperative stereotactic radiotherapy for the management of brain metastases

Traditionally, postoperative whole-brain radiation therapy (WBRT) has been used for resected brain metastases, reducing local and intracerebral relapses. However, WBRT is associated with cognitive deterioration. Postoperative stereotactic radiotherapy (SRT) has emerged due to its neurocognitive preservation benefits. Despite its advantages, postoperative SRT has several drawbacks, including difficulties in target volume delineation, increased risk of radionecrosis (RN) and leptomeningeal disease (LMD), and prolonged treatment duration. Preoperative SRT has been proposed as a potential alternative, offering promising results in retrospective studies. Retrospective studies have suggested that preoperative SRT could achieve high local control rates with fewer LMD and RN rates compared to postoperative SRT. However, preoperative SRT is primarily based on retrospective data, and no phase 2/3 trials have been published to date. Ongoing clinical trials are expected to provide further insights into the efficacy and safety of preoperative SRT, addressing key questions regarding fractionation, dose, and timing relative to surgery.

The Role of Repeated Surgical Resections for Recurrent Brain Metastases in Older Population

Background and Objectives: The impact of surgery for recurrent brain metastases in elderly patients has been the object of debate due to limited information in the literature. We analyzed clinical outcome and survival of elderly patients with recurrent brain metastases in order to assess potentially beneficial role of surgery. Materials and methods: In total, 219 patients with recurrent brain metastases between 2007 and 2022 were identified, of which 95 underwent re-resection; 83 patients aged 65 and older were analyzed. A survival analysis was performed, and clinical outcomes were evaluated. Results: The median survival time after surgery for recurrent brain metastases was 6 months (95CI 4-10) in older patients and 8 (95CI 7-9) in younger patients (p = 0.619). Out of all the older patients, 33 who underwent surgical resection showed prolonged survival compared with patients who did not receive surgical resection (median: 14, 95CI 8-19 vs. 4, 95CI 4-7, p = 0.011). All patients had preoperative Karnofsky performance scores of >70, which did not deteriorate after surgery (87.02 ± 5.76 vs. 85 ± 6.85; p = 0.055). In the univariate analysis, complete cytoreduction was a favorable prognostic factor. The tumor volume, the number of metastases, extracranial disease progression, adjuvant radiation, and systemic therapy did not affect survival in this cohort. Conclusions: Patients aged 65 and older benefit from neurosurgical resections of recurrent brain metastases. Survival did not differ from that in younger patients, which can be explained by a better preoperative functional status. Moreover, independent of the extent of resection, older patients who underwent surgery showed better survival than patients who did not receive surgical treatment. Complete cytoreduction was a favorable prognostic marker.

Intraoperative radiotherapy after neurosurgical resection of brain metastases as institutional standard treatment- update of the oncological outcome form a single center cohort after 117 procedures

PURPOSE

Stereotactic radiotherapy (SRT) is the predominant method for the irradiation of resection cavities after resection of brain metastases (BM). Intraoperative radiotherapy (IORT) with 50 kV x-rays is an alternative way to irradiate the resection cavity focally. We have already reported the outcome of our first 40 IORT patients treated until 2020. Since then, IORT has become the predominant cavity treatment in our center due to patients´ choice.

METHODS

We retrospectively analyzed the outcomes of all patients who underwent resection of BM and IORT between 2013 and August 2023 at Augsburg University Medical Center (UKA).

RESULTS

We identified 105 patients with 117 resected BM treated with 50 kV x-ray IORT. Median diameter of the resected metastases was 3.1 cm (range 1.3 - 7.0 cm). Median applied dose was 20 Gy. All patients received standardized follow-up (FU) including three-monthly MRI of the brain. Mean FU was 14 months, with a median MRI FU for patients alive of nine months. Median overall survival (OS) of all treated patients was 18.2 months (estimated 1-year OS 57.7%). The observed local control (LC) rate of the resection cavity was 90.5% (estimated 1-year LC 84.2%). Distant brain control (DC) was 61.9% (estimated 1-year DC 47.9%). Only 16.2% of all patients needed WBI in the further course of disease. The observed radio necrosis rate was 2.6%.

CONCLUSION

After 117 procedures IORT still appears to be a safe and appealing way to perform cavity RT after neurosurgical resection of BM with low toxicity and excellent LC.

Preoperative radiosurgery for brain metastases (PREOP-1): A feasibility trial

Purpose

Preoperative radiosurgery (SRS) of brain metastases (BM) aims to achieve cavity local control with a reduction in leptomeningeal relapse (LMD) and without additional radionecrosis compared to postoperative SRS. We present the final results of a prospective feasibility trial of linac-based stereotactic radiosurgery (SRS) prior to neurosurgical resection of a brain metastasis (PREOP-1).

Methods

Eligibility criteria included a BM up to 4 cm in diameter for elective resection. The primary endpoint was the feasibility of delivering linac-based preoperative SRS in all patients prior to anticipated gross tumour resection. Secondary endpoints included rates of LMD, local control and overall survival. Exploratory endpoints were the level of expression of immunological and proliferative markers.

Results

Thirteen patients of median age 65 years (range 41-77) were recruited. Twelve patients (92 %) received preoperative radiosurgery and metastasectomy and one patient went directly to surgery and received postoperative SRS, thus the primary endpoint was not met. The median time between referral and preoperative SRS was 6.5 working days (1-10) and from SRS to neurosurgery was 1 day (0-5). The median prescribed dose was 16 Gy (14-19) to a median planning target volume of 12.7 cm3 (5.9-26.1). Five patients completed 12-month follow-up after preoperative SRS without local recurrence or leptomeningeal disease. The patient who received postoperative FSRT developed LMD after six months. There was one transient toxicity (grade 2 alopecia) and nine patients have died from extracranial causes. Patients reported significant improvement in motor weakness at 6 months (P = 0.04). No pattern in changes of marker expression was observed.

Conclusion

In patients with large brain metastasis without raised intracranial pressure, linac-based preoperative SRS was feasible in 12/13 patients and safe in 12/12 patients without any surgical delay or intracranial complications.

Grade 5 Radiation Necrosis After Whole-Brain Radiation Therapy

Whole-brain radiation treatment is often considered for patients with leptomeningeal disease. There are limited reports of the development of radiation necrosis after whole-brain radiation treatment and fewer associating the presence of germline mutations with risk. We present a case report to highlight the need for consideration of radiosensitizing mutations when recommending radiation therapy.

[Comparative analysis of combined treatment methods for patients with single brain lesions]

Primary brain metastases are common in oncology. Preoperative stereotactic radiosurgery followed by surgical resection is a perspective approach.

OBJECTIVE

To evaluate own experience of preoperative radiosurgery followed by surgical resection (RS+S) of metastasis regarding local control, leptomeningeal progression, surgical and radiation-induced complications; to compare treatment outcomes with surgical resection and subsequent radiotherapy (S+SRT).

MATERIAL AND METHODS. A

Retrospective study included 66 patients with solitary brain metastasis. Two groups of patients were distinguished: group 1 (n=34) - postoperative irradiation, group 2 (n=32) - preoperative irradiation. The median age was 49.5 years (range 36-75).

RESULTS

Local 3-, 6- and 12-month control among patients with postoperative irradiation was 88.2%, 79.4% and 42.9%, in the group of preoperative irradiation - 100%, 93.3% and 66.7%, respectively (p=0.021). Leptomeningeal progression developed in 11 patients (8 and 3 ones, respectively). The one-year survival rate was 73.5% and 84.4%, respectively (p=0.33). Long-term surgical and radiation-induced complications occurred in 12 (18.2%) patients.

CONCLUSION

Preoperative radiosurgery with subsequent resection provides higher local control and lower incidence of leptomeningeal progression in patients with single brain metastases.

Brain metastasis treatment guidelines: consensus by the Spanish Society of Neurosurgery Tumor Section

Brain metastases are tumors that arise from a tumor cell originated in another organ reaching the brain through the blood. In the brain this tumor cell is capable of growing and invading neighboring tissues, such as the meninges and bone. In most patients a known tumor is present when the brain lesion is diagnosed, although it is possible that the first diagnose is the brain tumor before there is evidence of cancer elsewhere in the body. For this reason, the neurosurgeon must know the management that has shown the greatest benefit for brain metastasis patients, so treatments can be streamlined and optimized. Specifically, in this document, the following topics will be developed: selection of the cancer patient candidate for surgical resection and the role of the neurosurgeon in the multidisciplinary team, the importance of immunohistological and molecular diagnosis, surgical techniques, radiotherapy techniques, treatment updates of chemotherapy and immunotherapy and management algorithms in brain metastases. With this consensus manuscript, the tumor group of the Spanish Society of Neurosurgery (GT-SENEC) exposes the most relevant neurosurgical issues and the fundamental aspects to harmonize multidisciplinary treatment, especially with the medical specialties that are treating or will treat these patients.

Preoperative stereotactic radiosurgery as neoadjuvant therapy for resectable brain tumors

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Modern Stereotactic Radiotherapy for Brain Metastases from Lung Cancer: Current Trends and Future Perspectives Based on Integrated Translational Approaches

Brain metastases (BMs) represent the most frequent metastatic event in the course of lung cancer patients, occurring in approximately 50% of patients with non-small-cell lung cancer (NSCLC) and in up to 70% in patients with small-cell lung cancer (SCLC). Thus far, many advances have been made in the diagnostic and therapeutic procedures, allowing improvements in the prognosis of these patients. The modern approach relies on the integration of several factors, such as accurate histological and molecular profiling, comprehensive assessment of clinical parameters and precise definition of the extent of intracranial and extracranial disease involvement. The combination of these factors is pivotal to guide the multidisciplinary discussion and to offer the most appropriate treatment to these patients based on a personalized approach. Focal radiotherapy (RT), in all its modalities (radiosurgery (SRS), fractionated stereotactic radiotherapy (SRT), adjuvant stereotactic radiotherapy (aSRT)), is the cornerstone of BM management, either alone or in combination with surgery and systemic therapies. We review the modern therapeutic strategies available to treat lung cancer patients with brain involvement. This includes an accurate review of the different technical solutions which can be exploited to provide a "state-of-art" focal RT and also a detailed description of the systemic agents available as effective alternatives to SRS/SRT when a targetable molecular driver is present. In addition to the validated treatment options, we also discuss the future perspective for focal RT, based on emerging clinical reports (e.g., SRS for patients with many BMs from NSCLC or SRS for BMs from SCLC), together with a presentation of innovative and promising findings in translational research and the combination of novel targeted agents with SRS/SRT.

Opportunities and Alternatives of Modern Radiation Oncology and Surgery for the Management of Resectable Brain Metastases

Postsurgical radiotherapy (RT) has been early proven to prevent local tumor recurrence, initially performed with whole brain RT (WBRT). Subsequent to disadvantageous cognitive sequalae for the patient and the broad distribution of modern linear accelerators, focal irradiation of the tumor has omitted WBRT in most cases. In many studies, the effectiveness of local RT of the resection cavity, either as single-fraction stereotactic radiosurgery (SRS) or hypo-fractionated stereotactic RT (hFSRT), has been demonstrated to be effective and safe. However, whereas prospective high-level incidence is still lacking on which dose and fractionation scheme is the best choice for the patient, further ablative techniques have come into play. Neoadjuvant SRS (N-SRS) prior to resection combines straightforward target delineation with an accelerated post-surgical phase, allowing an earlier start of systemic treatment or rehabilitation as indicated. In addition, low-energy intraoperative RT (IORT) on the surgical bed has been introduced as another alternative to external beam RT, offering sterilization of the cavity surface with steep dose gradients towards the healthy brain. This consensus paper summarizes current local treatment strategies for resectable brain metastases regarding available data and patient-centered decision-making.

Efficacy of neoadjuvant stereotactic radiotherapy in brain metastases from solid cancer: a systematic review of literature and meta-analysis

Neoadjuvant stereotactic radiotherapy (NaSRT) is a novel strategy for brain metastasis (BM) treatment, promising to achieve good local control, improved survival, and low toxicity. This is a systematic review of available literature and meta-analysis of 8 articles eligible for inclusion after searching MEDLINE via PubMed, Web-of-science, Cochrane Wiley, and Embase databases up to March 2023. A total of 484 patients undergoing NaSRT to treat 507 lesions were included. The median age was 60.9 (IQR 57-63) years, with a median tumor volume of 12.1 (IQR 9-14) cm3. The most frequent histology was non-small-cell lung cancer (41.3%), followed by breast (18.8%), and melanoma (14.3%). Lesions had a preferred supratentorial location (77.4%). Most of the studies used a single fraction schedule (91% of patients, n = 440). Treatment parameters were homogeneous and showed a median dose of 18 (IQR 15.5-20.5) Gy at a median of 80% isodose. Surgery was performed after a median of 1.5 (IQR 1-2.4) days and achieved gross-total extent in 94% of cases. Median follow-up was 12.9 (IQR 10-15.7) months. NaSRT showed an overall mortality rate of 58% (95% CI 43-73) at the last follow-up. Actuarial outcomes rates were 60% (95% CI 55-64) for 1-year overall survival (1y-OS), 38% (95% CI 33-43) for 2y-OS, 29% (95% CI 24-34) for 3y-OS; overall 15% (95% CI 11-19) for local failure, 46% (95% CI 37-55) for distant brain failure, 6% (95% CI 3-8) for radionecrosis, and 5% (95% CI 3-8) for leptomeningeal dissemination. The median local progression-free survival time was 10.4 (IQR 9.5-11.4) months, while the median survival without distant failure was 7.4 (IQR 6.9-8) months. The median OS time for the entire cohort was 17 (IQR 14.9-17.9) months. Existing data suggest that NaSRT is effective and safe in the treatment of BMs, achieving good local control on BMs with and low incidence of radionecrosis and leptomeningeal dissemination. Distant control appears limited compared to other radiation regimens.

Efficacy of Stereotactic Radiosurgery as Single or Combined Therapy for Brain Metastasis: A Systematic Review and Meta-Analysis

To determine the efficacy of stereotactic radiosurgery (SRS) in treating patients with brain metastases (BMs), a network meta-analysis (NMA) of randomized controlled trials (RCTs) and a direct comparison of cohort studies were performed. Relevant literature regarding the effectiveness of SRS alone and in combination with whole-brain radiotherapy (WBRT) and surgery was retrieved using systematic database searches up to April 2019. The patterns of overall survival (OS), one-year OS, progression-free survival (PFS), one-year local brain control (LBC), one-year distant brain control (DBC), neurological death (ND), and complication rate were analyzed. A total of 18 RCTs and 37 cohorts were included in the meta-analysis. Our data revealed that SRS carried a better OS than SRS+WBRT (p= 0.048) and WBRT (p= 0.041). Also, SRS+WBRT demonstrated a significantly improved PFS, LBC, and DBC compared to WBRT alone and SRS alone. Finally, SRS achieved the same LBC as high as surgery, but intracranial relapse occurred considerably more frequently in the absence of WBRT. However, there were not any significant differences in ND and toxicities between SRS and other groups. Therefore, SRS alone may be a better alternative since increased patient survival may outweigh the increased risk of brain tumor recurrence associated with it.

Predictors of Survival After Stereotactic Radiosurgery for Untreated Single Non-Small Cell Lung Cancer Brain Metastases: 5- and 10-year Results

BACKGROUND

Stereotactic radiosurgery (SRS) presents as a good treatment option for smaller, deep-seated brain metastases (BMs). This study aims to determine predictors of SRS failure for patients with non-small cell lung cancer BMs.

METHODS

This was a retrospective study of single non-small cell lung cancer BMs treated using SRS. We included patients >18 years with a single, previously untreated lesion. Primary outcome was treatment failure, defined as BMs dimension increase above the initial values. Demographic, clinical, and radiological data were collected to study potential predictors of treatment failure.

RESULTS

Worse rates of progression-free survival (PFS) were associated with heterogeneous contrast enhancement (18.1 ± 4.1 vs. 41.9 ± 4 months; P < 0.001). Better rates of PFS were associated with volumes <1.06 cm3 (log-rank; P = 0.001). Graded prognostic assessment was significantly associated with survival at 120 months (log-rank; P < 0.001). Karnofsky Performance Scale was evaluated in 3 strata: 90-100, 80, and ≤70. Mean survival rates for these strata were 31.8 ± 3.9, 10.6 ± 2.2, and 9.8 ± 2.3 months, respectively (log-rank; P < 0.001). There were no differences regarding presence of extracranial metastases, age, or lesion location. A multivariable logistic regression found that volume <1.06 cm3 was associated with higher survival rates at 10 years (odds ratio: 3.2, 95% confidence interval: 1.3-8.0).

CONCLUSIONS

Contrast-homogeneous metastases and lesions <1.06 cm3 are associated with better rates of PFS. Karnofsky Performance Scale and graded prognostic assessment were associated with more favorable survival rates after 10 years. Volume <1.06 cm3 was the only significant predictor of survival in the multivariable analysis.

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.

What if: A retrospective reconstruction of resection cavity stereotactic radiosurgery to mimic neoadjuvant stereotactic radiosurgery

Introduction

Neoadjuvant stereotactic radiosurgery (NaSRS) of brain metastases has gained importance, but it is not routinely performed. While awaiting the results of prospective studies, we aimed to analyze the changes in the volume of brain metastases irradiated pre- and postoperatively and the resulting dosimetric effects on normal brain tissue (NBT).

Methods

We identified patients treated with SRS at our institution to compare hypothetical preoperative gross tumor and planning target volumes (pre-GTV and pre-PTV) with original postoperative resection cavity volumes (post-GTV and post-PTV) as well as with a standardized-hypothetical PTV with 2.0 mm margin. We used Pearson correlation to assess the association between the GTV and PTV changes with the pre-GTV. A multiple linear regression analysis was established to predict the GTV change. Hypothetical planning for the selected cases was created to assess the volume effect on the NBT exposure. We performed a literature review on NaSRS and searched for ongoing prospective trials.

Results

We included 30 patients in the analysis. The pre-/post-GTV and pre-/post-PTV did not differ significantly. We observed a negative correlation between pre-GTV and GTV-change, which was also a predictor of volume change in the regression analysis, in terms of a larger volume change for a smaller pre-GTV. In total, 62.5% of cases with an enlargement greater than 5.0 cm3 were smaller tumors (pre-GTV < 15.0 cm3), whereas larger tumors greater than 25.0 cm3 showed only a decrease in post-GTV. Hypothetical planning for the selected cases to evaluate the volume effect resulted in a median NBT exposure of only 67.6% (range: 33.2-84.5%) relative to the dose received by the NBT in the postoperative SRS setting. Nine published studies and twenty ongoing studies are listed as an overview.

Conclusion

Patients with smaller brain metastases may have a higher risk of volume increase when irradiated postoperatively. Target volume delineation is of great importance because the PTV directly affects the exposure of NBT, but it is a challenge when contouring resection cavities. Further studies should identify patients at risk of relevant volume increase to be preferably treated with NaSRS in routine practice. Ongoing clinical trials will evaluate additional benefits of NaSRS.

Local therapy treatment conditions for oligometastatic non-small cell lung cancer

Standard treatments for patients with metastatic non-small cell lung cancer (NSCLC) include palliative chemotherapy and radiotherapy, but with limited survival rates. With the development of improved immunotherapy and targeted therapy, NSCLC prognoses have significantly improved. In recent years, the concept of oligometastatic disease has been developed, with randomized trial data showing survival benefits from local ablation therapy (LAT) in patients with oligometastatic NSCLC (OM-NSCLC). LAT includes surgery, stereotactic ablation body radiation therapy, or thermal ablation, and is becoming an important treatment component for OM-NSCLC. However, controversy remains on specific management strategies for the condition. In this review, we gathered current randomized trial data to analyze prognostic factors affecting patient survival, and explored ideal treatment conditions for patients with OM-NSCLC with respect to long-term survival.

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.

Preoperative stereotactic radiosurgery in the management of brain metastases and gliomas

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

Hypofractionated postoperative stereotactic radiotherapy for large resected brain metastases

PURPOSE

The aim of the present retrospective study was to report outcomes after hypofractionated stereotactic radiotherapy (HSRT) for resected brain metastases (BM).

PATIENTS AND METHODS

We reviewed results of patients with resected BM treated with postoperative HSRT (3×7.7Gy to the prescription isodose 70%) between May 2013 and June 2020. Local control (LC), distant brain control (DBC), overall survival (OS), leptomeningeal disease relapse (LMDR), and radiation necrosis (RN) occurrence were reported.

RESULTS

Twenty-two patients with 23 brain cavities were included. Karnofsky Performance status (KPS) was≥70 in 77.3%. Median preoperative diameter was 37mm [21.0-75.0] and median planning target volume (PTV) was 23 cm³ [9.9-61.6]. Median time from surgery to SRT was 69 days [7-101] and 48% of patients had a local relapse on pre-SRT imaging. Median follow-up was 17.5 months [1.6-95.9]. One and two-year LC rates were 60.9 and 52.2% respectively. One and 2-year DBC rates were 45.5 and 40.9%. Median OS was 16.5 months. Four patients (18.2%) presented LMDR during follow-up. RN occurred in 6 patients (27.2%). Three factors were associated with OS: ECOG-PS (P=0.009), KPS (P=0.04), and cystic metastasis before surgery (P=0.037). Several factors were related to RN occurrence: PTV diameter and volume, Normal brain V21, V21 and V24 isodoses volumes.

CONCLUSION

HSRT is the most widely used scheme for larger brain cavities after surgery. The optimal dose and scheme remain to be defined as well as the optimal delay between postoperative SRT and surgery. Dose escalation may be necessary, especially in case of subtotal resection.

Neoadjuvant Stereotactic Radiotherapy for Brain Metastases: Systematic Review and Meta-Analysis of the Literature and Ongoing Clinical Trials

Simple Summary

The available treatment strategies for patients with brain metastases remain suboptimal, with current research focused on identifying therapies intended to improve patient outcomes while reducing the risk of treatment-related complications. Several studies have investigated the role of pre-operative neoadjuvant stereotactic radiotherapy, and have proposed it as a valid alternative to post-operative adjuvant stereotactic radiotherapy. The aim of our systematic review was to comprehensively analyze the current literature and ongoing clinical trials evaluating neoadjuvant stereotactic radiotherapy in patients with brain metastases, describing treatment protocols and related outcomes. Early evidence suggests that neoadjuvant stereotactic radiotherapy may offer rates of local control and overall survival comparable to those obtained with adjuvant postoperative SRS, but comparative studies are currently lacking. In addition, neoadjuvant stereotactic radiotherapy shows low rates of post-treatment radiation necrosis and leptomeningeal metastases. Ongoing clinical trials aim to evaluate long-term outcomes in large patient cohorts, with some focused on comparing neoadjuvant stereotactic radiotherapy to adjuvant stereotactic radiosurgery.

Abstract

Background: Brain metastases (BMs) carry a high morbidity and mortality burden. Neoadjuvant stereotactic radiotherapy (NaSRT) has shown promising results. We systematically reviewed the literature on NaSRT for BMs. Methods: PubMed, EMBASE, Scopus, Web-of-Science, Cochrane, and ClinicalTrial.gov were searched following the PRISMA guidelines to include studies and ongoing trials reporting NaSRT for BMs. Indications, protocols, and outcomes were analyzed using indirect random-effect meta-analyses. Results: We included 7 studies comprising 460 patients with 483 BMs, and 13 ongoing trials. Most BMs originated from non-small lung cell carcinoma (41.4%), breast cancer (18.7%) and melanoma (43.6%). Most patients had single-BM (69.8%) located supratentorial (77.8%). Patients were eligible if they had histologically-proven primary tumors and ≤4 synchronous BMs candidate for non-urgent surgery and radiation. Patients with primary tumors clinically responsive to radiotherapy, prior brain radiation, and leptomeningeal metastases were deemed non-eligible. Median planning target volume was 9.9 cm³ (range, 2.9–57.1), and NaSRT was delivered in 1-fraction (90.9%), 5-fraction (4.8%), or 3-fraction (4.3%), with a median biological effective dose of 39.6 Gy10 (range, 35.7–60). Most patients received piecemeal (76.3%) and gross-total (94%) resection after a median of 1-day (range, 1–10) post-NaSRT. Median follow-up was 19.2-months (range, 1–41.3). Actuarial post-treatment rates were 4% (95%CI: 2–6%) for symptomatic radiation necrosis, 15% (95%CI: 12–18%) and 47% (95%CI: 42–52%) for local and distant recurrences, 6% (95%CI: 3–8%) for leptomeningeal metastases, 81% (95%CI: 75–87%) and 59% (95%CI: 54–63%) for 1-year local tumor control and overall survival. Conclusion: NaSRT is effective and safe for BMs. Ongoing trials will provide high-level evidence on long-term post-treatment outcomes, further compared to adjuvant stereotactic radiotherapy.

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.

Radiation Therapy for Brain Metastases: An ASTRO Clinical Practice Guideline

PURPOSE

This guideline provides updated evidence-based recommendations addressing recent developments in the management of patients with brain metastases, including advanced radiation therapy techniques such as stereotactic radiosurgery (SRS) and hippocampal avoidance whole brain radiation therapy and the emergence of systemic therapies with central nervous system activity.

METHODS

The American Society for Radiation Oncology convened a task force to address 4 key questions focused on the radiotherapeutic management of intact and resected brain metastases from nonhematologic solid tumors. The guideline is based on a systematic review provided by the Agency for Healthcare Research and Quality. Recommendations were created using a predefined consensus-building methodology and system for grading evidence quality and recommendation strength.

RESULTS

Strong recommendations are made for SRS for patients with limited brain metastases and Eastern Cooperative Oncology Group performance status 0 to 2. Multidisciplinary discussion with neurosurgery is conditionally recommended to consider surgical resection for all tumors causing mass effect and/or that are greater than 4 cm. For patients with symptomatic brain metastases, upfront local therapy is strongly recommended. For patients with asymptomatic brain metastases eligible for central nervous system-active systemic therapy, multidisciplinary and patient-centered decision-making to determine whether local therapy may be safely deferred is conditionally recommended. For patients with resected brain metastases, SRS is strongly recommended to improve local control. For patients with favorable prognosis and brain metastases receiving whole brain radiation therapy, hippocampal avoidance and memantine are strongly recommended. For patients with poor prognosis, early introduction of palliative care for symptom management and caregiver support are strongly recommended.

CONCLUSIONS

The task force has proposed recommendations to inform best clinical practices on the use of radiation therapy for brain metastases with strong emphasis on multidisciplinary care.

Is there any survival benefit from post-operative radiation in brain metastases? A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The benefits of adding upfront post-operative radiation, either whole-brain (WBRT) or cavity, after resection of brain metastases have been debated, particularly due to the long-term sequalae post radiation. We sought to compare the efficacy and safety between post-operative radiation versus resection alone.

METHODS

We searched various biomedical databases from 1983 to 2018, for eligible randomized controlled trials (RCT). Outcomes studied were local recurrence (LR), overall survival (OS) and serious (Grade 3 + ) adverse events. We used the random effects model to pool outcomes. Methodological quality of each study was assessed using the Cochrane Risk of Bias tool. We employed the GRADE approach to assess the certainty of evidence.

RESULTS

We included 5 RCTs comprising of 673 patients. The pooled odds ratio (OR) for LR is 0.26 (95% confidence interval (CI) 0.19-0.37, P < 0.001, GRADE certainty high), strongly supporting the use of post-operative radiation. Meta-regression analysis done comparing cavity and WBRT, did not show any difference in LR. The pooled hazard ratio (HR) for overall survival (OS) is 1.1 (95% CI 0.90-1.34, P = 0.37, GRADE certainty high). The treatment-related toxicities could not be pooled; the 2 studies which reported this did not find differences between the approaches. The risk of bias across the included studies was low.

CONCLUSION

Our analysis confirms that upfront post-operative radiation significantly reduces the risk of LR. However, the lack of improvement in OS suggests that local control alone may not impact survival. Balancing local control, and neuro-cognitive effects of WBRT, cavity radiation seems to be a safe and effective option.

Evaluation of the impact of pre-operative stereotactic radiotherapy on the acute changes in histopathologic and immune marker profiles of brain metastases

The unique acute effects of the large fractional doses that characterize stereotactic radiosurgery (SRS) or radiotherapy (SRT), specifically in terms of antitumor immune cellular processes, vascular damage, tumor necrosis, and apoptosis on brain metastasis have yet to be empirically demonstrated. The objective of this study is to provide the first in-human evaluation of the acute biological effects of SRS/SRT in resected brain metastasis. Tumor samples from patients who underwent dose-escalated preoperative SRT followed by resection with available non-irradiated primary tumor tissues were retrieved from our institutional biorepository. All primary tumors and irradiated metastases were evaluated for the following parameters: tumor necrosis, T-cells, natural killer cells, vessel density, vascular endothelial growth factor, and apoptotic factors. Twenty-two patients with irradiated and resected brain metastases and paired non-irradiated primary tumor samples met inclusion criteria. Patients underwent a median preoperative SRT dose of 18 Gy (Range: 15–20 Gy) in 1 fraction, with 3 patients receiving 27–30 Gy in 3–5 fractions, followed by resection within median interval of 67.8 h (R: 18.25–160.61 h). The rate of necrosis was significantly higher in irradiated brain metastases than non-irradiated primary tumors (p < 0.001). Decreases in all immunomodulatory cell populations were found in irradiated metastases compared to primary tumors: CD3 + (p = 0.003), CD4 + (p = 0.01), and CD8 + (p = 0.01). Pre-operative SRT is associated with acute effects such as increased tumor necrosis and differences in expression of immunomodulatory factors, an effect that does not appear to be time dependent, within the limited intervals explored within the context of this analysis.

Neoadjuvant fractionated stereotactic radiotherapy followed by piecemeal resection of brain metastasis: a case series of 20 patients

BACKGROUND

The safety and effectiveness of neoadjuvant fractionated stereotactic radiotherapy (FSRT) before piecemeal resection of brain metastasis (BM) remains unknown.

METHODS

We retrospectively reviewed 20 consecutive patients with BM who underwent neoadjuvant FSRT followed by piecemeal resection between July 2019 and March 2021. The prescribed dose regimens were as follows: 30 Gy (n = 11) or 35 Gy (n = 9) in five fractions.

RESULTS

The mean follow-up duration was 7.8 months (range 2.2-22.3). The median age was 67 years (range 51-79). Fourteen patients were male. All patients were symptomatic. All tumors were located in the supratentorial compartment. The median maximum diameter and volume were 3.7 cm (range 2.6-4.9) and 17.6 cm3 (range 5.6-49.7), respectively. The median time from the end of FSRT to resection was 4 days (range 1-7). Nausea (CTCAE Grade 2) occurred in one patient and simple partial seizures (Grade 2) in two patients during radiation therapy. Gross total removal was performed in seventeen patients and sub-total removal in three patients. Postoperative complications were deterioration of paresis in two patients. Local recurrence was found in one patient (5.0%) who underwent sub-total resection at 2 months after craniotomy. Distant recurrence was found in six patients (30.0%) at a median of 6.9 months. Leptomeningeal disease recurrence was found in one patient (5.0%) at 3 months. No radiation necrosis developed.

CONCLUSIONS

Neoadjuvant FSRT appears to be a safe and effective approach for patients with BM requiring piecemeal resection. A multi-institutional prospective trial is needed.

Intraoperative radiotherapy with low-energy x-rays after neurosurgical resection of brain metastases-an Augsburg University Medical Center experience

PURPOSE

External-beam radiotherapy (EBRT) is the predominant method for localized brain radiotherapy (LBRT) after resection of brain metastases (BM). Intraoperative radiotherapy (IORT) with 50-kV x‑rays is an alternative way to focally irradiate the resection cavity after BM surgery, with the option of shortening the overall treatment time and limiting normal tissue irradiation.

METHODS

We retrospectively analyzed the outcomes of all patients who underwent neurosurgical resection of BM and 50-kV x‑ray IORT between 2013 and 2020 at Augsburg University Medical Center.

RESULTS

We identified 40 patients with 44 resected BM treated with 50-kV x‑ray IORT. Median diameter of the resected metastases was 2.8 cm (range 1.5-5.9 cm). Median applied dose was 20 Gy. All patients received standardized follow-up (FU) including 3‑monthly MRI of the brain. Mean FU was 14.4 months, with a median MRI FU for alive patients of 12.2 months. Median overall survival (OS) of all treated patients was 26.4 months (estimated 1‑year OS 61.6%). The observed local control (LC) rate of the resection cavity was 88.6% (estimated 1‑year LC 84.3%). Distant brain control (DC) was 47.5% (estimated 1‑year DC 33.5%). Only 25% of all patients needed WBI in the further course of disease. The observed radionecrosis rate was 2.5%.

CONCLUSION

IORT with 50-kV x‑rays is a safe and appealing way to apply LBRT after neurosurgical resection of BM, with low toxicity and excellent LC. Close MRI FU is paramount to detect distant brain failure (DBF) early.

Time to administration of stereotactic radiosurgery to the cavity after surgery for brain metastases: a real-world analysis

OBJECTIVE

Publications on adjuvant stereotactic radiosurgery (SRS) are largely limited to patients completing SRS within a specified time frame. The authors assessed real-world local recurrence (LR) for all brain metastasis (BM) patients referred for SRS and identified predictors of SRS timing.

METHODS

The authors retrospectively identified BM patients undergoing resection and referred for SRS between 2012 and 2018. Patients were categorized by time to SRS, as follows: 1) ≤ 4 weeks, 2) > 4-8 weeks, 3) > 8 weeks, and 4) never completed. The relationships between timing of SRS and LR, LR-free survival (LRFS), and survival were investigated, as well as predictors of and reasons for specific SRS timing.

RESULTS

In a cohort of 159 patients, the median age at resection was 64.0 years, 56.5% of patients were female, and 57.2% were in recursive partitioning analysis (RPA) class II. The median preoperative tumor diameter was 2.9 cm, and gross-total resection was achieved in 83.0% of patients. All patients were referred for SRS, but 20 (12.6%) did not receive it. The LR rate was 22.6%, and the time to SRS was correlated with the LR rate: 2.3% for patients receiving SRS at ≤ 4 weeks postoperatively, 14.5% for SRS at > 4-8 weeks (p = 0.03), and 48.5% for SRS at > 8 weeks (p < 0.001). No LR difference was seen between patients whose SRS was delayed by > 8 weeks and those who never completed SRS (48.5% vs 50.0%; p = 0.91). A similar relationship emerged between time to SRS and LRFS (p < 0.01). Non-small cell lung cancer pathology (p = 0.04), earlier year of treatment (p < 0.01), and interval from brain MRI to SRS (p < 0.01) were associated with longer intervals to SRS. The rates of receipt of systemic therapy also differed significantly between patients by category of time to SRS (p = 0.02). The most common reasons for intervals of > 4-8 weeks were logistic, whereas longer delays or no SRS were caused by management of systemic disease or comorbidities.

CONCLUSIONS

Available data on LR rates after adjuvant SRS are often obtained from carefully preselected patients receiving timely treatment, whereas significantly less information is available on the efficacy of adjuvant SRS in patients treated under "real-world" conditions. Management of these patients may merit reconsideration, particularly when SRS is not delivered within ≤ 4 weeks of resection. The results of this study indicate that a substantial number of patients referred for SRS either never receive it or are treated > 8 weeks postoperatively, at which time the SRS-treated patients have an LR risk equivalent to that of patients who never received SRS. Increased attention to the reasons for prolonged intervals from surgery to SRS and strategies for reducing them is needed to optimize treatment. For patients likely to experience delays, other radiotherapy techniques may be considered.

Modern Radiation Therapy for the Management of Brain Metastases From Non-Small Cell Lung Cancer: Current Approaches and Future Directions

Brain metastases (BMs) represent the most frequent event during the course of Non-Small Cell Lung Cancer (NSCLC) disease. Recent advancements in the diagnostic and therapeutic procedures result in increased incidence and earlier diagnosis of BMs, with an emerging need to optimize the prognosis of these patients through the adoption of tailored treatment solutions. Nowadays a personalized and multidisciplinary approach should rely on several clinical and molecular factors like patient’s performance status, extent and location of brain involvement, extracranial disease control and the presence of any “druggable” molecular target. Radiation therapy (RT), in all its focal (radiosurgery and fractionated stereotactic radiotherapy) or extended (whole brain radiotherapy) declinations, is a cornerstone of BMs management, either alone or combined with surgery and systemic therapies. Our review aims to provide an overview of the many modern RT solutions available for the treatment of BMs from NSCLC in the different clinical scenarios (single lesion, oligo and poly-metastasis, leptomeningeal carcinomatosis). This includes a detailed review of the current standard of care in each setting, with a presentation of the literature data and of the possible technical solutions to offer a “state-of-art” treatment to these patients. In addition to the validated treatment options, we will also discuss the future perspectives on emerging RT technical strategies (e.g., hippocampal avoidance whole brain RT, simultaneous integrated boost, radiosurgery for multiple lesions), and present the innovative and promising findings regarding the combination of novel targeted agents such as tyrosine kinase inhibitors and immune checkpoint inhibitors with brain irradiation.

Risk of tract recurrence with stereotactic biopsy of brain metastases: an 18-year cancer center experience

OBJECTIVE

Stereotactic biopsy is increasingly performed on brain metastases (BrMs) as improving cancer outcomes drive aggressive multimodality treatment, including laser interstitial thermal therapy (LITT). However, the tract recurrence (TR) risk is poorly defined in an era defined by focused-irradiation paradigms. As such, the authors aimed to define indications and adjuvant therapies for this procedure and evaluate the BrM-biopsy TR rate.

METHODS

In a single-center retrospective review, the authors identified stereotactic BrM biopsies performed from 2002 to 2020. Surgical indications, radiographic characteristics, stereotactic planning, dosimetry, pre- and postoperative CNS-directed and systemic treatments, and clinical courses were collected. Recurrence was evaluated using RANO-BM (Response Assessment in Neuro-Oncology Brain Metastases) criteria.

RESULTS

In total, 499 patients underwent stereotactic intracranial biopsy for any diagnosis, of whom 25 patients (5.0%) underwent biopsy for pathologically confirmed viable BrM, a proportion that increased over the time period studied. Twelve of the 25 BrM patients had ≥ 3 months of radiographic follow-up, of whom 6 patients (50%) developed new metastatic growth along the tract at a median of 5.0 months post-biopsy (range 2.3-17.1 months). All of the TR cases had undergone pre- or early post-biopsy stereotactic radiosurgery (SRS), and 3 had also undergone LITT at the time of initial biopsy. TRs were treated with resection, reirradiation, or observation/systemic therapy.

CONCLUSIONS

In this study the authors identified a nontrivial, higher than previously described rate of BrM-biopsy tract recurrence, which often required additional surgery or radiation and justified close radiographic surveillance. As BrMs are commonly treated with SRS limited to enhancing tumor margins, consideration should be made, in cases lacking CNS-active systemic treatments, to include biopsy tracts in adjuvant radiation plans where feasible.

Successful salvage of recurrent leptomeningeal disease in large cell neuroendocrine lung cancer with stereotactic radiotherapy

A 70-year old male with stage I large cell neuroendocrine carcinoma (LCNEC) of the lung underwent resection of a metachronous 5 cm brain metastasis and received postoperative hypofractionated stereotactic radiotherapy (hfSRT). Five sequential nodular leptomeningeal metastases up to 5.3 cm in diameter were diagnosed on MRI within 10 months and were treated with SRT. Currently the patient has no evidence of intracranial disease 24 months after last irradiation without chemotherapy or whole brain radiotherapy. This is the first report of sustained complete remission of multiple large leptomeningeal metastases achieved with hfSRT, highlighting this brain-sparing approach in selected patients with LCNEC lung cancer.

Preoperative stereotactic radiosurgery for brain metastases: the STEP study protocol for a multicentre, prospective, phase-II trial

Background

Surgery is an important therapeutic option for brain metastases. Currently, postoperative stereotactic radiosurgery (SRT) leads to 6-month and 1-year local control estimated at 70 and 62% respectively. However, there is an increased risk of radio-necrosis and leptomeningeal relapse. Preoperative SRT might be an alternative, providing local control remains at least equivalent. It is an innovative concept that could enable the stereotactic benefits to be retained with advantages over post-operative SRT.

Methods

STEP has been designed as a national, multicentre, open-label, prospective, non-randomized, phase-II trial. Seventeen patients are expected to be recruited in the study from 7 sites and they will be followed for 12 months. Patients with more than 4 distinct brain metastases, including one with a surgical indication, and an indication for SRT and surgery, are eligible for enrolment. The primary objective of the trial is to assess 6-month local control after preoperative SRT. The secondary objectives include the assessment of local control, radio-necrosis, overall survival, toxicities, leptomeningeal relapse, distant control, cognitive function, and quality of life. The experimental design is based on a Flemming plan.

Discussion

There is very little data available in the literature on preoperative SRT: there have only been 3 American single or two-centre retrospective studies. STEP is the first prospective trial on preoperative SRT in Europe. Compared to postoperative stereotactic radiotherapy, preoperative stereotactic radiotherapy will enable reduction in the irradiated volume, leptomeningeal relapse and the total duration of the combined treatment (from 4 to 6 weeks to a few days).

Trial registration number

Clinicaltrials.gov: NCT04503772, registered on August 07, 2020. Identifier with the French National Agency for the Safety of Medicines and Health Products (ANSM): N°ID RCB 2020-A00403–36, registered in February 2020. Protocol: version 4, 07 December 2020.

Preoperative Radiosurgery for Resected Brain Metastases: The PROPS-BM Multicenter Cohort Study

PURPOSE

Preoperative radiosurgery (SRS) is a feasible alternative to postoperative SRS, with potential benefits in adverse radiation effect (ARE) and leptomeningeal disease (LMD) relapse. However, previous studies are limited by small patient numbers and single-institution designs. Our aim was to evaluate preoperative SRS outcomes and prognostic factors from a large multicenter cohort (Preoperative Radiosurgery for Brain Metastases [PROPS-BM]).

METHODS AND MATERIALS

Patients with brain metastases (BM) from solid cancers who had at least 1 lesion treated with preoperative SRS and underwent a planned resection were included from 5 institutions. SRS to synchronous intact BM was allowed. Radiographic meningeal disease (MD) was categorized as either nodular or classical "sugarcoating" (cLMD).

RESULTS

The cohort included 242 patients with 253 index lesions. Most patients (62.4%) had a single BM, 93.7% underwent gross total resection, and 98.8% were treated with a single fraction to a median dose of 15 Gray to a median gross tumor volume of 9.9 cc. Cavity local recurrence (LR) rates at 1 and 2 years were 15% and 17.9%, respectively. Subtotal resection (STR) was a strong independent predictor of LR (hazard ratio, 9.1; P < .001). One and 2-year rates of MD were 6.1% and 7.6% and of any grade ARE were 4.7% and 6.8% , respectively. The median overall survival (OS) duration was 16.9 months and the 2-year OS rate was 38.4%. The majority of MD was cLMD (13 of 19 patients with MD; 68.4%). Of 242 patients, 10 (4.1%) experienced grade ≥3 postoperative surgical complications.

CONCLUSIONS

To our knowledge, this multicenter study represents the largest cohort treated with preoperative SRS. The favorable outcomes previously demonstrated in single-institution studies, particularly the low rates of MD and ARE, are confirmed in this expanded multicenter analysis, without evidence of an excessive postoperative surgical complication risk. STR, though infrequent, is associated with significantly worse cavity LR. A randomized trial between preoperative and postoperative SRS is warranted and is currently being designed.

Durable 5-year local control for resected brain metastases with early adjuvant SRS: the effect of timing on intended-field control

Background

Adjuvant stereotactic radiosurgery (SRS) improves the local control of resected brain metastases (BrM). However, the dependency of long-term outcomes on SRS timing relative to surgery remains unclear.

Methods

Retrospective analysis of patients treated with metastasectomy-plus-adjuvant SRS at Memorial Sloan Kettering Cancer Center (MSK) between 2013 and 2016 was conducted. Kaplan-Meier methodology was used to describe overall survival (OS) and cumulative incidence rates were estimated by type of recurrence, accounting for death as a competing event. Recursive partitioning analysis (RPA) and competing risks regression modeling assessed prognostic variables and associated events of interest.

Results

Two hundred and eighty-two patients with BrM had a median OS of 1.5 years (95% CI: 1.2-2.1) from adjuvant SRS with median follow-up of 49.8 months for survivors. Local surgical recurrence, other simultaneously SRS-irradiated site recurrence, and distant central nervous system (CNS) progression rates were 14.3% (95% CI: 10.1-18.5), 4.9% (95% CI: 2.3-7.5), and 47.5% (95% CI: 41.4-53.6) at 5 years, respectively. Median time-to-adjuvant SRS (TT-SRS) was 34 days (IQR: 27-39). TT-SRS was significantly associated with surgical site recurrence rate (P = 0.0008). SRS delivered within 1 month resulted in surgical site recurrence rate of 6.1% (95% CI: 1.3-10.9) at 1-year, compared to 9.2% (95% CI: 4.9-13.6) if delivered between 1 and 2 months, or 27.3% (95% CI: 0.0-55.5) if delivered >2 months after surgery. OS was significantly lower for patients with TT-SRS >~2 months. Postoperative length of stay, discharge to a rehabilitation facility, urgent care visits, and/or disease recurrence between surgery and adjuvant SRS associated with increased TT-SRS.

Conclusions

Adjuvant SRS provides durable local control. However, delays in initiation of postoperative SRS can decrease its efficacy.

Treatment Options for Leptomeningeal Metastases of Solid Cancers: Literature Review and Personal Experience

Leptomeningeal metastases (LM) may complicate the clinical course of any solid cancer or hematological malignancy. Diagnosis of such cases requires a multifaceted approach, including careful evaluation of the clinical history, detailed neurological examination, advanced imaging studies, and related laboratory data analysis. Therapeutic options for management of LM have not been standardized yet. Conventional intrathecal chemotherapy with or without involved-field fractionated radiotherapy has only modest efficacy, and the prognosis of most patients remains grim. Therefore, development of new, more aggressive multimodal treatment strategies is definitely needed. Immune checkpoint inhibitors-in particular, molecular targeted therapy-have demonstrated promising results in selected groups of patients. There may be an important role for stereotactic radiosurgery as well. Because organization of prospective randomized multi-institutional trials on treatment of LM of solid cancers may be problematic, practical guidelines for optimal therapeutic strategies in such cases should be established on the basis of integrated results of small-scale prospective and retrospective studies.

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.

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.

Medical management of brain metastases

The development of brain metastases occurs in 10–20% of all patients with cancer. Brain metastases portend poor survival and contribute to increased cancer mortality and morbidity. Despite multimodal treatment options, which include surgery, radiotherapy, and chemotherapy, 5-year survival remains low. Besides, our current treatment modalities can have significant neurological comorbidities, which result in neurocognitive decline and a decrease in a patient’s quality of life. However, innovations in technology, improved understanding of tumor biology, and new therapeutic options have led to improved patient care. Novel approaches in radiotherapy are minimizing the neurocognitive decline while providing the same therapeutic benefit. In addition, advances in targeted therapies and immune checkpoint inhibitors are redefining the management of lung and melanoma brain metastases. Similar approaches to brain metastases from other primary tumors promise to lead to new and effective therapies. We are beginning to understand the appropriate combination of these novel approaches with our traditional treatment options. As advances in basic and translational science and innovative technologies enter clinical practice, the prognosis of patients with brain metastases will continue to improve.

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.

Current approaches to the management of brain metastases

Brain metastases are a very common manifestation of cancer that have historically been approached as a single disease entity given the uniform association with poor clinical outcomes. Fortunately, our understanding of the biology and molecular underpinnings of brain metastases has greatly improved, resulting in more sophisticated prognostic models and multiple patient-related and disease-specific treatment paradigms. In addition, the therapeutic armamentarium has expanded from whole-brain radiotherapy and surgery to include stereotactic radiosurgery, targeted therapies and immunotherapies, which are often used sequentially or in combination. Advances in neuroimaging have provided additional opportunities to accurately screen for intracranial disease at initial cancer diagnosis, target intracranial lesions with precision during treatment and help differentiate the effects of treatment from disease progression by incorporating functional imaging. Given the numerous available treatment options for patients with brain metastases, a multidisciplinary approach is strongly recommended to personalize the treatment of each patient in an effort to improve the therapeutic ratio. Given the ongoing controversies regarding the optimal sequencing of the available and expanding treatment options for patients with brain metastases, enrolment in clinical trials is essential to advance our understanding of this complex and common disease. In this Review, we describe the key features of diagnosis, risk stratification and modern paradigms in the treatment and management of patients with brain metastases and provide speculation on future research directions.

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.

Neoadjuvant stereotactic radiosurgery for intracerebral metastases of solid tumors (NepoMUC): a phase I dose escalation trial

Background

More than 25% of patients with solid cancers develop intracerebral metastases. Aside of surgery, radiation therapy (RT) is a mainstay in the treatment of intracerebral metastases. Postoperative fractionated stereotactic RT (FSRT) to the resection cavity of intracerebral metastases is a treatment of choice to reduce the risk of local recurrence. However, FSRT has to be delayed until a sufficient wound healing is attained; hence systemic therapy might be postponed. Neoadjuvant stereotactic radiosurgery (SRS) might offer advantages over adjuvant FSRT in terms of better target delineation and an earlier start of systemic chemotherapy. Here, we conducted a study to find the maximum tolerated dose (MTD) of neoadjuvant SRS for intracerebral metastases.

Methods

This is a single-center, phase I dose escalation study on neoadjuvant SRS for intracerebral metastases that will be conducted at the Klinikum rechts der Isar Hospital, Technical University of Munich. The rule-based traditional 3 + 3 design for this trial with 3 dose levels and 4 different cohorts depending on lesion size will be applied. The primary endpoint is the MTD for which no dose-limiting toxicities (DLT) occur. The adverse events of each participant will be evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 continuously during the study until the first follow-up visit (4–6 weeks after surgery). Secondary endpoints include local control rate, survival, immunological tumor characteristics, quality of life (QoL), CTCAE grade of late clinical, neurological, and neurocognitive toxicities. In addition to the intracerebral metastasis which is treated with neoadjuvant SRS and resection up to four additional intracerebral metastases can be treated with definitive SRS. Depending on the occurrence of DLT up to 72 patients will be enrolled. The recruitment phase will last for 24 months.

Discussion

Neoadjuvant SRS for intracerebral metastases offers potential advantages over postoperative SRS to the resection cavity, such as better target volume definition with subsequent higher efficiency of eliminating tumor cells, and lower damage to surrounding healthy tissue, and much-needed systemic chemotherapy could be initiated more rapidly.

Trial registration The local ethical review committee of Technical University of Munich (199/18S) approved this study on September 05, 2018. This trial was registered on German Clinical Trials Register (DRKS00016613; https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00016613) on January 29, 2019.

Preoperative stereotactic radiosurgery before planned resection of brain metastases: updated analysis of efficacy and toxicity of a novel treatment paradigm

OBJECTIVE

Preoperative stereotactic radiosurgery (SRS) is a feasible alternative to postoperative SRS and may lower the risk of radiation necrosis (RN) and leptomeningeal disease (LMD) recurrence. The study goal was to report the efficacy and toxicity of preoperative SRS in an expanded patient cohort with longer follow-up period relative to prior reports.

METHODS

The records for patients with brain metastases treated with preoperative SRS and planned resection were reviewed. Patients with classically radiosensitive tumors, planned adjuvant whole brain radiotherapy, or no cranial imaging at least 1 month after surgery were excluded. Preoperative SRS dose was based on lesion size and was reduced approximately 10-20% from standard dosing. Surgery generally followed within 48 hours.

RESULTS

The study cohort consisted of 117 patients with 125 lesions treated with single-fraction preoperative SRS and planned resection. Of the 117 patients, 24 patients were enrolled in an initial prospective trial; the remaining 93 cases were consecutively treated patients who were retrospectively reviewed. Most patients had a single brain metastasis (70.1%); 42.7% had non-small cell lung cancer, 18.8% had breast cancer, 15.4% had melanoma, and 11.1% had renal cell carcinoma. Gross total resection was performed in 95.2% of lesions. The median time from SRS to surgery was 2 days, the median SRS dose was 15 Gy, and the median gross tumor volume was 8.3 cm3. Event cumulative incidence at 2 years was as follows: cavity local recurrence (LR), 25.1%; distant brain failure, 60.2%; LMD, 4.3%; and symptomatic RN, 4.8%. The median overall survival (OS) and 2-year OS rate were 17.2 months and 36.7%, respectively. Subtotal resection (STR, n = 6) was significantly associated with increased risk of cavity LR (hazard ratio [HR] 6.67, p = 0.008) and worsened OS (HR 2.63, p = 0.05) in multivariable analyses.

CONCLUSIONS

This expanded and updated analysis confirms that single-fraction preoperative SRS confers excellent cavity local control with very low risk of RN or LMD. Preoperative SRS has several potential advantages compared to postoperative SRS, including reduced risk of RN due to smaller irradiated volume without need for cavity margin expansion and reduced risk of LMD due to sterilization of tumor cells prior to spillage at the time of surgery. Subtotal resection, though infrequent, is associated with significantly worse cavity LR and OS. Based on these results, a randomized trial of preoperative versus postoperative SRS is being designed.

A multi-institutional analysis of presentation and outcomes for leptomeningeal disease recurrence after surgical resection and radiosurgery for brain metastases

BACKGROUND

Radiographic leptomeningeal disease (LMD) develops in up to 30% of patients following postoperative stereotactic radiosurgery (SRS) for brain metastases. However, the clinical relevancy of this finding and outcomes after various salvage treatments are not known.

METHODS

Patients with brain metastases, of which 1 was resected and treated with adjunctive SRS, and who subsequently developed LMD were combined from 7 tertiary care centers. LMD pattern was categorized as nodular (nLMD) or classical ("sugarcoating," cLMD).

RESULTS

The study cohort was 147 patients. Most patients (60%) were symptomatic at LMD presentation, with cLMD more likely to be symptomatic than nLMD (71% vs. 51%, P = 0.01). Salvage therapy was whole brain radiotherapy (WBRT) alone (47%), SRS (27%), craniospinal radiotherapy (RT) (10%), and other (16%), with 58% receiving a WBRT-containing regimen. WBRT was associated with lower second LMD recurrence compared with focal RT (40% vs 68%, P = 0.02). Patients with nLMD had longer median overall survival (OS) than those with cLMD (8.2 vs 3.3 mo, P < 0.001). On multivariable analysis for OS, pattern of initial LMD (nodular vs classical) was significant, but type of salvage RT (WBRT vs focal) was not.

CONCLUSIONS

Nodular LMD is a distinct pattern of LMD associated with postoperative SRS that is less likely to be symptomatic and has better OS outcomes than classical "sugarcoating" LMD. Although focal RT demonstrated increased second LMD recurrence compared with WBRT, there was no associated OS detriment. Focal cranial RT for nLMD recurrence after surgery and SRS for brain metastases may be a reasonable alternative to WBRT.

Focal Management of Large Brain Metastases and Risk of Leptomeningeal Disease

Purpose

Surgery is often used for large or symptomatic brain metastases but is associated with risk of developing leptomeningeal dissemination. Emerging data suggest that fractionated stereotactic radiation therapy (FSRT) is an effective management strategy in large brain metastases. We sought to retrospectively compare leptomeningeal disease (LMD) and local control (LC) rates for patients treated with surgical resection followed by radiosurgery (S + SRS) versus FSRT alone.

Methods and Materials

We identified all patients with a brain metastasis ≥3 cm in diameter treated from 2004 to 2017 with S + SRS or FSRT alone (25 or 30 Gy in 5 fractions) who had follow-up imaging. LMD was defined as focal or diffuse leptomeningeal enhancement that was >5 mm from the index metastasis. Categorical baseline characteristics were compared with the χ² test. LMD and LC rates were evaluated by the Kaplan-Meier (KM) method, with the log-rank test used to compare subgroups.

Results

A total of 125 patients were identified, including 82 and 43 in the S + SRS and FSRT alone groups, respectively. Median pretreatment Graded Prognostic Assessment in the S + SRS and FSRT groups was 2.5 and 1.5, respectively (P < .001). Median follow-up was 7 months. The KM estimate of 12-month LMD rate in the S + SRS and FSRT groups was 45% and 19%, respectively (P = .048). The KM estimate of 12-month local control in the S + SRS and FSRT groups was 70% and 69%, respectively (P = .753). The 12-month KM estimate of grade ≥3 toxicity was 1.4% in S + SRS group versus 6.3% in the FSRT alone group (P = .248). After adjusting for graded prognostic assessment (GPA), no overall survival difference was observed between groups (P = .257).

Conclusions

Surgery is appropriate for certain brain metastases, but S + SRS may increase LMD risk compared with FSRT alone. Because S + SRS and FSRT seem to have similar LC, FSRT may be a viable alternative to S + SRS in select patients with large brain metastases.