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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Proteomics shows that brain metastases of lung adenocarcinoma overexpress ribosomal proteins in response to gamma knife radiosurgery

Gamma knife radiosurgery (GKRS) is recommended as the first-line treatment for brain metastases of lung adenocarcinoma (LUAD) in many guidelines, but its specific mechanism is unclear. We aimed to study the changes in the proteome of brain metastases of LUAD in response to the hyperacute phase of GKRS and further explore the mechanism of differentially expressed proteins (DEPs). Cancer tissues were collected from a clinical trial for neoadjuvant stereotactic radiosurgery before surgical resection of large brain metastases (ChiCTR2000038995). Five brain metastasis tissues of LUAD were collected within 24 h after GKRS. Five brain metastasis tissues without radiotherapy were collected as control samples. Proteomics analysis showed that 163 proteins were upregulated and 25 proteins were downregulated. GO and KEGG enrichment analyses showed that the DEPs were closely related to ribosomes. Fifty-three of 70 ribosomal proteins were significantly overexpressed, while none of them were underexpressed. The risk score constructed from 7 upregulated ribosomal proteins (RPL4, RPS19, RPS16, RPLP0, RPS2, RPS26 and RPS25) was an independent risk factor for the survival time of LUAD patients. Overexpression of ribosomal proteins may represent a desperate response to lethal radiotherapy. We propose that targeted inhibition of these ribosomal proteins may enhance the efficacy of GKRS.

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.

Preoperative Versus Postoperative Radiosurgery of Brain Metastases: A Meta-Analysis

OBJECTIVE

While postoperative resection cavity radiosurgery (post-SRS) is an accepted treatment paradigm for brain metastasis (BM) patients who undergo surgical resection, there is emerging interest in preoperative radiosurgery (pre-SRS) followed by surgical resection as an alternative treatment paradigm. Here, we performed a meta-analysis of the available literature on this matter.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a search of all studies evaluating pre-SRS and post-SRS was completed. Local recurrence (LR), overall survival (OS), radiation necrosis (RN), and leptomeningeal disease (LMD) were evaluated from the available data. Moderator analysis and pooled effect sizes were performed using a proportional meta-analysis with R using the metafor package. Statistics are presented as mean [95% confidence interval].

RESULTS

We identified 6 pre-SRS and 33 post-SRS studies with comparable tumor volume (4.5-17.6 cm3). There were significant differences in the pooled estimates of LR and LMD, favoring pre-SRS over post-SRS. Pooled aggregate for LR was 11.0% [4.9-13.7] and 17.5% [15.1-19.9] for pre- and post-SRS studies (P = 0.014). Similarly, pooled estimates of LMD favored pre-SRS, 4.4% [2.6-6.2], relative to post-SRS, 12.3% [8.9-15.7] (P = 0.019). In contrast, no significant differences were found in terms of RN and OS. Pooled estimates for RN were 6.4% [3.1-9.6] and 8.9% [6.3-11.6] for pre- and post-SRS studies (P = 0.393), respectively. Pooled estimates for OS were 60.2% [55.8-64.6] and 60.5% [56.9-64.0] for pre- and post-SRS studies (P = 0.974).

CONCLUSIONS

This meta-analysis supports further exploration of pre-SRS as a strategy for the treatment of BM.

Evaluation of Circulating Tumor DNA as a Liquid Biomarker in Uveal Melanoma

Purpose

Uveal melanoma (UM) has a high propensity to metastasize. Prognosis is associated with specific driver mutations and copy number variations (CNVs), but limited primary tumor tissue is available for molecular characterization due to eye-sparing irradiation treatment. This study aimed to assess the rise in circulating tumor DNA (ctDNA) levels in UM and evaluate its efficacy for CNV-profiling of patients with UM.

Methods

In a pilot study, we assessed ctDNA levels in the blood of patients with UM (n = 18) at various time points, including the time of diagnosis (n = 13), during fractionated stereotactic radiotherapy (fSRT) treatment (n = 6), and upon detection of metastatic disease (n = 13). Shallow whole-genome sequencing (sWGS) combined with in silico size-selection was used to identify prognostically relevant CNVs in patients with UM (n = 26) from peripheral blood retrieved at the time of diagnosis (n = 9), during fSRT (n = 5), during post-treatment follow-up (n = 4), metastasis detection (n = 6), and metastasis follow-up (n = 4).

Results

A total of 34 patients had blood analyzed for ctDNA detection (n = 18) and/or CNV analysis (n = 26) at various time points. At the time of diagnosis, 5 of 13 patients (38%) had detectable ctDNA (median = 0 copies/mL). Upon detection of metastatic disease, ctDNA was detected in 10 of 13 patients (77%) and showed increased ctDNA levels (median = 24 copies/mL, P < 0.01). Among the six patients analyzed during fSRT, three (50%) patients had detectable ctDNA at baseline and three of six (50%) patients had undetectable levels of ctDNA. During the fSRT regimen, ctDNA levels remained unchanged (P > 0.05). The ctDNA fractions were undetectable to low in localized disease, and sWGS did not elucidate chromosome 3 status from blood samples. However, in 7 of 10 (70%) patients with metastases, the detection of chromosome 3 loss corresponded to the high metastatic-risk class.

Conclusions

The rise in ctDNA levels observed in patients with UM harboring metastases suggests its potential utility for CNV profiling. These findings highlight the potential of using ctDNA for metastasis detection and patient inclusion in therapeutic studies targeting metastatic UM.

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.

Anatomical and surgical characteristics correlate with pachymeningeal failure in patients with brain metastases after neurosurgical resection and adjuvant stereotactic radiosurgery

PURPOSE

Neurosurgery (NS) is an essential modality for large brain metastases (BM). Postoperative stereotactic radiosurgery (SRS) is the standard of care adjuvant treatment. Pachymeningeal failure (PMF) is a newly described entity, distinct from classical leptomeningeal failure (LMF), that is uniquely observed in postoperative patients treated with adjuvant SRS. We sought to identify risk factors for PMF in patients treated with NS + SRS.

METHODS

From a prospective registry (2009 to 2021), we identified all patients treated with NS + SRS. Clinical, imaging, pathological, and treatment factors were analyzed. PMF incidence was evaluated using a competing risks model.

RESULTS

144 Patients were identified. The median age was 62 (23-90). PMF occurred in 21.5% (31/144). Female gender [Hazard Ratio (HR) 2.65, p = 0.013], higher Graded Prognostic Assessment (GPA) index (HR 2.4, p < 0.001), absence of prior radiation therapy (HR N/A, p = 0.018), controlled extracranial disease (CED) (HR 3.46, p = 0.0038), and pia/dura contact (PDC) (HR 3.30, p = 0.0053) were associated with increased risk for PMF on univariate analysis. In patients with PDC, wider target volumes correlated with reduced risk of PMF. Multivariate analysis indicated PDC (HR 3.51, p = 0.0053), piecemeal resection (HR 2.38, p = 0.027), and CED (HR 3.97, p = 0.0016) independently correlated with PMF risk. PMF correlated with reduced OS (HR 2.90, p < 0.001) at a lower rate compared to LMF (HR 10.15, p < 0.001).

CONCLUSION

PMF correlates with tumor PDC and piecemeal resection in patients treated with NS + SRS. For unclear reasons, it is also associated with CED. In tumors with PDC, wider dural radiotherapy coverage was associated with a lower risk of PMF.

Update on the Management of Brain Metastasis

Brain metastases occur in almost one-third of adult patients with solid tumor malignancies and lead to considerable patient morbidity and mortality. The rising incidence of brain metastases has been ascribed to the development of better imaging and screening techniques and the formulation of better systemic therapies. Until recently, the multimodal management of brain metastases focused primarily on the utilization of neurosurgical techniques, with varying combinations of whole-brain radiation therapy and stereotactic radio-surgical procedures. Over the past 2 decades, in particular, the increment in knowledge pertaining to molecular genetics and the pathogenesis of brain metastases has led to significant developments in targeted therapies and immunotherapies. This review article highlights the recent updates in the management of brain metastases with an emphasis on novel systemic therapies.

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.