Stereotactic radiosurgery plus whole-brain radiation therapy vs stereotactic radiosurgery alone for treatment of brain metastases: a randomized controlled trial

The Impact of Margin Expansions on Local Control and Radionecrosis Following Stereotactic Radiosurgery for Brain Metastases: A Systematic Review and Meta-Analysis

PURPOSE

The implications of margin expansions on local control (LC) and radionecrosis (RN) for treating brain metastases (BMs) with stereotactic radiosurgery (SRS) remain unclear. We performed a systematic review and meta-analysis to compare LC and RN between patients with BMs treated with SRS planned with no margin versus a margin.

METHODS AND MATERIALS

We used the Population, Intervention, Control, Outcomes, Study Design; the Preferred Reporting Items for Systematic Reviews; and Meta-analyses, and the Meta-analysis of Observational Studies in Epidemiology selection inclusion criteria for studies of patients with BMs treated with SRS with no margin or a margin. Primary outcomes were 1-year LC and radiographic and symptomatic RN incidences. Weighted random effects meta-analyses were performed to compare effect sizes.

RESULTS

Across 17 studies, we identified 5015 lesions treated with SRS (1360 lesions with no margin and 3684 with a margin). The median total margin was 1.5 (range, 1-3) mm. Single-fraction SRS was most common with a median prescription dose of 21 Gy (range, 15-24 Gy). The estimated 1-year LC rate was similar with a margin (88.4% [95% CI, 83.7%-92.4%]) versus without (83.0% [95% CI, 69.3-93.2%; P = 0.28]). The estimated incidences of radiographic RN after SRS with or without a margin were 9.2% (95% CI, 0.2%-29.6%) and 7.0% (95% CI, 4.1%-10.7%; P = 0.56), respectively. The estimated incidences of symptomatic RN after SRS without or with a margin were 8.6% (95% CI, 5.2%-12.7%) and 4.1% (95% CI, 0.9%-9.3%), respectively (P = .24).

CONCLUSIONS

We did not note a significant difference in LC or RN between patients treated with or without margin expansions. Prospective evaluations are warranted to further assess this question while controlling for other relevant treatment planning and metastasis considerations.

Stereotactic radiosurgery for patients with brain metastases: current principles, expanding indications and opportunities for multidisciplinary care

The management of brain metastases is challenging and should ideally be coordinated through a multidisciplinary approach. Stereotactic radiosurgery (SRS) has been the cornerstone of management for most patients with oligometastatic central nervous system involvement (one to four brain metastases), and several technological and therapeutic advances over the past decade have broadened the indications for SRS to include polymetastatic central nervous system involvement (>4 brain metastases), preoperative application and fractionated SRS, as well as combinatorial approaches with targeted therapy and immune-checkpoint inhibitors. For example, improved imaging and frameless head-immobilization technologies have facilitated fractionated SRS for large brain metastases or postsurgical cavities, or lesions in proximity to organs at risk. However, these opportunities come with new challenges and questions, including the implications of tumour histology as well as the role and sequencing of concurrent systemic treatments. In this Review, we discuss these advances and associated challenges in the context of ongoing clinical trials, with insights from a global group of experts, including recommendations for current clinical practice and future investigations. The updates provided herein are meaningful for all practitioners in clinical oncology.

Dosimetric predictors of toxicity for brainstem metastases and AVMs treated with stereotactic radiosurgery: An international, multi-institutional analysis

BACKGROUND

There are limited data on dosimetric predictors of radiation-induced changes (RICs) for brainstem metastases or arteriovenous malformations (AVMs) following single-fraction stereotactic radiosurgery (SRS).

METHODS

We examined a multi-institutional cohort of patients with brainstem metastases or AVMs treated with SRS. We evaluated predictors of RICs graded per CTCAE(Common Terminology Criteria for Adverse Events), including D5%, D95%, D0.03 cc, and D0.5 cc (brainstem minus lesion). Univariate logistic regressions were initially performed with independent variables trending towards significance included on multivariate logistic regression.

RESULTS

A total of 124 brainstem lesions treated with SRS were analyzed (21 AVMs and 103 metastases). The median prescription dose was 16 Gy(range: 13-23 Gy), and the median treatment volume was 0.48 cc(range: 0.002-11.19 cc). The incidence of RICs was 9.7 % (with 3/12 being Grade 3-4 and no Grade 5). All cases occurred in brainstem metastases, with no cases among those of the midbrain-pons transition. Treatment volumes ≥ 1cc were correlated with a higher symptomatic RIC incidence(6/57 vs. 6/65; p = 0.04). Notably, all RIC cases had a D0.5 cc ≥ 15 Gy(12/87 vs. 0/32). Both D5%≥6 Gy(9/55 vs. 3/69; p = 0.04) and D95%≥1 Gy(7/31 vs. 5/93; p = 0.01) were significantly correlated with higher incidence of RICs and D0.03 cc ≥ 22 Gy was correlated with a lower risk(2/61 vs. 9/63; p = 0.03). On MVA, D0.03 cc ≥ 22 Gy remained a significant predictor of a lower incidence of RICs(odds ratio = -1.72 (95 % CI: -3.32 to -0.12; p = 0.04).

CONCLUSIONS

Incidence of RICs was low following SRS for brainstem metastases and AVMs. We recommend optimizing radiosurgical plans for D0.5 cc < 15 Gy with consideration of D5% and D95%, with less emphasis on D0.03 cc to allow to meet the former metrics as feasible.

Immunotherapy may promote the occurrence of radiation-induced brain injury in NSCLC patients with brain metastases undergoing radiotherapy: a retrospective propensity score-matching and inverse probability of treatment weighting study

PURPOSE

The combination of radiotherapy (RT) and immunotherapy can significantly improve the prognosis of non-small cell lung cancer (NSCLC) patients. However, concerns about whether the synergistic effect may increase the risk of radiation-induced brain injury (RIBI) remain controversial. This study aims to explore the impact of immune checkpoint inhibitors (ICIs) on the occurrence of RIBI in patients with NSCLC brain metastases (BMs).

METHODS

This study retrospectively enrolled NSCLC patients with BMs undergoing RT between January 2017 and December 2023. Patients were stratified into groups based on PD-1/PD-L1 checkpoint inhibitors, administration, with confounding factors controlled via propensity score matching (PSM) and inverse probability of treatment weighting (IPTW). Final cohorts included an RT-only group (n = 54) and an RT + ICIs group (n = 28). RIBI incidence and progression-free survival (PFS) were compared between groups.

RESULTS

After 1:1 PSM analysis, the incidence of RIBI in the RT + ICIs group was significantly higher than that in the RT-only group (17.9% vs 42.9%, P = 0.042). Further IPTW analysis showed that the incidence of RIBI in the RT + ICIs group was significantly higher than that in the RT-only group (24.8% vs 47.8%, P = 0.033). Regarding the impact on PFS, there was no statistical difference between the two groups in both PSM and IPTW (P > 0.05).

CONCLUSIONS

Immunotherapy combined with RT may increase the occurrence of RIBI in patients with NSCLC BMs. The mechanism underlying this phenomenon requires further investigation.

Optimization of target grouping in distributive stereotactic radiosurgery using the excel evolutionary solver

PURPOSE

Distributive stereotactic radiosurgery (dSRS) is a form of fractionation where groups of metastases are treated with a full single-fraction dose on different days. The challenge with dSRS is determining optimal target groupings to maximize the distance between targets treated in the same fraction. This study aimed to develop and validate an accessible optimization technique for distributing brain metastases into optimal treatment fractions using a genetic algorithm.

METHODS

The Evolutionary Solver in Excel was used to optimize the grouping of target volumes for distributive SRS fractionation. The algorithm's performance was tested using three geometric test cases with known optimal solutions, 400 simulations with randomly distributed target volumes, and clinical data from five GammaKnife patients. The objective function was defined as the sum of average distances between target volumes within each fraction, with constraints ensuring 2-5 targets per fraction, each target being assigned to only one fraction, and a constraint on the minimum distance between any two targets in the same fraction.

RESULTS

The Evolutionary Solver successfully identified optimal target groupings in all geometric test cases. Compared to random groupings, the mean distance between target volumes increased by 9%, from 68.1 ± 0.8  to 74.2 ± 1.1 mm post-optimization, while the minimum distance between targets increased by 57%, from 24.9 ± 5.9  to 39.1 ± 7.5 mm. In clinical test cases, the mean distances improved from 81.6 ± 11.9 mm for manual target grouping to 85.6 ± 14.5 mm for optimized target grouping. The minimum separation improved from 35.2 ± 14.5 mm with manual grouping to 51.6 ± 14.7 mm with optimized grouping, corresponding to a mean improvement of 16.4 ± 6.1 mm.

CONCLUSION

The Evolutionary Solver in Excel provides a systematic and reproducible method for optimizing distributive target groupings in SRS and enhances spatial separation.

Stereotactic and fractionated stereotactic radiosurgery for single and multiple brain metastases: Results of multicenter planning studies

PURPOSE

Stereotactic and fractionated stereotactic radiosurgery (SRS/fSRS) utilization is growing in India, although planning studies are scarce. This study assessed clinical practices for SRS/fSRS treatment planning for brain metastases (BM) using ICRU-91 and explored the impact of planning tools.

METHODS & MATERIALS

Participants from 23 centers received two anonymized CT datasets with predrawn structures for single met (SM) and four BMs (MM) cases via email. Centers used local protocol to create plans. The plans were evaluated for target coverage, normal brain doses, and ICRU-91 dosimetric indices.

RESULTS

Monaco TPS overestimated mean GTV (PTV) by 3.7 (4.2)% and 2.1 (2.0)% for SM and MM respectively. Some institutions had good conformity and target coverage, whereas others had high OAR doses despite inadequate PTV dose coverage. Conformity index (CI) ranged from 1.07 to 1.45 (SM) and 1.06 to 1.25 (MM), and homogeneity index (HI) ranged from 0.07 to 0.28 (SM) and 0.13 to 0.32 (MM). Significant variation in GI and dose prescription isodose line selection was observed among centers.

CONCLUSIONS

There was a significant heterogeneity in the planning parameters noted among different centers. The study emphasized the importance of established planning protocols and comprehensive training for staff involved in SRS/fSRS. Notably, plans with finer MLC width outperformed, yet wider MLC plans achieved ICRU-91 indices comparable to published literature. The importance of our study is underscored by the absence of a national framework for SRS planning in India.

MRI distortion correction is associated with improved local control in stereotactic radiotherapy for brain metastases

Distortions in brain MRI caused by gradient nonlinearities may reach several millimeters, thus distortion correction is strongly recommended for radiotherapy treatment planning. However, the significance of MRI distortion correction on actual clinical outcomes has not been described yet. Therefore, we investigated the impact of planning MRI distortion correction on subsequent local control in a historic series of 419 brain metastases in 189 patients treated with stereotactic radiotherapy between 01/2003 and 04/2015. Local control was evaluated using a volumetric extension of the RANO-BM criteria. The predictive significance of distortion correction was assessed using competing risk analysis. In this cohort, 2D distortion-corrected MRIs had been used for treatment planning in 52.5% (220/419) of lesions, while uncorrected MRIs had been employed in 47.5% (199/419) of metastases. 2D distortion correction was associated with improved local control (Cumulative incidence of local progression at 12 months: 14.3% vs. 21.2% and at 24 months: 18.7% vs. 28.6%, p = 0.038). In multivariate analysis, adjusting for histology, baseline tumor volume, interval between MRI and treatment delivery, year of planning MRI, biologically effective dose and adjuvant Whole-brain radiotherapy, use of distortion correction remained significantly associated with improved local control (HR 0.55, p = 0.020). This is the first study to clinically evaluate the impact of MRI gradient nonlinearity distortion correction on local control in stereotactic radiotherapy for brain metastases. In this historic series, we found significantly higher local control when using 2D corrected vs. uncorrected MRI studies for treatment planning. These results stress the importance of assuring that MR images used for radiotherapy treatment planning are properly distortion-corrected.

Multidisciplinary management strategies for recurrent brain metastasis after prior radiotherapy: An overview

As cancer patients with intracranial metastatic disease experience increasingly prolonged survival, the diagnosis and management of recurrent brain metastasis pose significant challenges in clinical practice. Prior to deciding upon a management strategy, it is necessary to ascertain whether patients have recurrent/progressive disease vs adverse radiation effect, classify the recurrence as local or distant in the brain, evaluate the extent of intracranial disease (size, number and location of lesions, and brain metastasis velocity), the status of extracranial disease, and enumerate the interval from the last intracranially directed intervention to disease recurrence. A spectrum of salvage local treatment options includes surgery (resection and laser interstitial thermal therapy [LITT]) with or without adjuvant radiotherapy in the forms of external beam radiotherapy, intraoperative radiotherapy, or brachytherapy. Nonoperative salvage local treatments also range from single fraction and fractionated stereotactic radiosurgery (SRS/FSRS) to whole brain radiation therapy (WBRT). Optimal integration of systemic therapies, preferably with central nervous system (CNS) activity, may also require reinterrogation of brain metastasis tissue to identify actionable molecular alterations specific to intracranial progressive disease. Ultimately, the selection of the appropriate management approach necessitates a sophisticated understanding of patient, tumor, and prior treatment-related factors and is often multimodal; hence, interdisciplinary evaluation for such patients is indispensable.

Efficacy of 3D-TSE sequence-based radiosurgery in prolonging time to distant intracranial failure: A session-wise analysis in a histology-diverse patient cohort

BACKGROUND

Stereotactic radiosurgery (SRS) for patients with brain metastases (BM) is associated with a risk of distant intracranial failure (DIF). This study evaluates the impact of integrating dedicated 3D fast/turbo spin echo (3D-TSE) sequences to MPRAGE in BM detection and DIF prolongation in a histology-agnostic patient cohort.

METHODS

The study population included adults treated with SRS from February 2019 to January 2024 who underwent MPRAGE alone or dual sequence with the addition of 3D-TSE starting from February 2020. Median times to DIF were estimated using the Kaplan-Meier method.

RESULTS

The 216 study patients who underwent 332 SRS courses for 1456 BM imaged with MPRAGE and 3D-TSE (primary cohort) were compared to a control cohort (92 patients, 135 SRS courses, 462 BM). In the session-wise analysis, the median time to DIF between the cohorts was significantly prolonged in the primary vs. control cohorts (11.4 vs. 6.8 months, P = .029), more pronounced in the subgroups with 1-4 metastases (14.7 vs. 8.1 months, P = .008) and with solitary BM (36.4 vs. 10.9 months, P = .001). While patients relapsing on immunotherapy or targeted therapy did not significantly benefit from 3D-TSE (7.2 vs. 5.7 months, P = .280), those who relapsed on chemotherapy or who were off systemic therapy (including synchronous metastases) exhibited a trend toward longer time to DIF with 3D-TSE integration (14.7 vs. 7.9 months, P = .057).

CONCLUSIONS

Implementing 3D-TSE sequences into SRS practice increases BM detection across all patients and translates into clinical relevance by prolonging time to DIF, particularly in those with limited intracranial disease and those not receiving central nervous system-active agents.

Stereotactic Radiosurgery for Intramedullary Spinal Cord Metastases: A Systematic Review and Meta-Analysis

Intramedullary spinal cord metastases (ISCM) represent a rare but increasingly diagnosed cancer dissemination. Stereotactic radiosurgery (SRS) and fractionated stereotactic radiosurgery (FSRS) have emerged as a local treatment option in this context over recent years. This systematic review and meta-analysis aim to assess the safety and effectiveness of SRS/FSRS in ISCM. A systematic literature review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, searching in PubMed/MEDLINE and Google Scholar databases. Studies were selected based on predefined criteria, with bias risk evaluated using Joanna Briggs Institute (JBI) tools. Relevant data were extracted for subsequent meta-analysis. Descriptive statistics and survival analysis using Kaplan-Meier were performed. Ten studies including 60 patients and 77 ISCM treated with SRS/FSRS were selected. The median age was 50 years, with a female predominance (70%). Breast cancer was the most common metastatic origin (41.7%). Kaplan-Meier analysis in 27 patients showed an estimated overall survival (OS) at 12 months of 35.33% (95% CI 0.18-0.53) and at 24 months of 25.98% (95% CI 0.11-0.44), with a median OS of nine months (95% CI 5.2-14). Local control was achieved in 86.3% at the end of follow-up, with favorable neurological control in 69% of patients and no spinal cord toxicity. The findings of this systematic review and meta-analysis suggest that SRS/FSRS appears to be safe and effective in treating ISCM. However, given the low quality of the included studies, these results should be interpreted with caution. Prospective studies are needed to better define the role of SRS/FSRS and evaluate spinal toxicity in this context.

Central Nervous System Metastases in Endometrial Carcinoma: A Case Series

Central nervous system metastases from endometrial carcinoma are a rare occurrence and suggest that metastatic endometrial carcinoma can have variable presentations. In this case report, we present three separate cases of patients diagnosed with endometrial carcinoma with metastasis to the central nervous system. The first case presents a woman with grade 2 endometrioid adenocarcinoma with mucinous and clear cell features found later to have skull metastasis with extradural extension. The second case presents a patient with an endometrial yolk sac tumor who, years after her primary diagnosis, was found to have metastasis to the brain. The final case is a woman with endometrial adenocarcinoma who developed brain metastases. While rare, it is important to consider the possibility of the presence of distal bone and brain metastases in patients with endometrial carcinoma. Special attention must be given when these patients report new neurologic symptoms, and one must consider early brain imaging.

Invasion and metastasis in cancer: molecular insights and therapeutic targets

The progression of malignant tumors leads to the development of secondary tumors in various organs, including bones, the brain, liver, and lungs. This metastatic process severely impacts the prognosis of patients, significantly affecting their quality of life and survival rates. Research efforts have consistently focused on the intricate mechanisms underlying this process and the corresponding clinical management strategies. Consequently, a comprehensive understanding of the biological foundations of tumor metastasis, identification of pivotal signaling pathways, and systematic evaluation of existing and emerging therapeutic strategies are paramount to enhancing the overall diagnostic and treatment capabilities for metastatic tumors. However, current research is primarily focused on metastasis within specific cancer types, leaving significant gaps in our understanding of the complex metastatic cascade, organ-specific tropism mechanisms, and the development of targeted treatments. In this study, we examine the sequential processes of tumor metastasis, elucidate the underlying mechanisms driving organ-tropic metastasis, and systematically analyze therapeutic strategies for metastatic tumors, including those tailored to specific organ involvement. Subsequently, we synthesize the most recent advances in emerging therapeutic technologies for tumor metastasis and analyze the challenges and opportunities encountered in clinical research pertaining to bone metastasis. Our objective is to offer insights that can inform future research and clinical practice in this crucial field.

Neurosurgical management of brain metastases in the elderly: a prospective study on adverse event prevalence and predictors

The management of brain metastases (BM) in geriatric patients poses significant challenges in the context of an aging population and advances in systemic cancer treatment. This study provides insights into the prevalence and nature of adverse events (AEs) following intracranial surgery in patients aged 65 years and older. It highlights the complexities and implications of treating this demographic patient population and identifies risk factors associated with AEs. This prospective study includes patients aged 65 years and older with BM who underwent surgery between January 2022 and December 2023. A detailed assessment of AEs, defined as any complication occurring within the first 30 days post-surgery, was conducted. Potential risk factors for the occurrence of AEs were examined. The study encompassed 104 patients, averaging 70.1 ± 2.8 years, with 102 undergoing surgery. The mean age-adjusted Charlson Comorbidity Index (CCI) score was 8.9 ± 1.2, indicating a significant comorbidity burden, predominantly cardiac conditions. The Karnofsky Performance Scale (KPS) showed substantial improvement post-surgery, increasing from 71.3% ± 7.8 to 75.1% ± 5.0 (p = 0.045). The average hospital stay was 10.6 days. Four non-surgery-related mortalities occurred within the 30-day postoperative period. Surgery-related AEs included wound complications in two patients, with one necessitating surgical revision. Advanced age and comorbidities emerged as significant predictors of AEs. Our findings suggest that neurosurgical intervention for BM in the elderly is a feasible and safe option, demonstrating favorable morbidity and mortality rates. However, careful postoperative monitoring is crucial, especially considering the baseline health status of these patients, which increases their susceptibility to AEs. Standardizing protocols for AE reporting and analysis is essential for improving clinical outcomes and maintaining the quality of healthcare for this patient population.

Outcomes of Patients With Five or More Brain Metastases Treated With Stereotactic Radiosurgery From 2014 to 2019: A UK Series

AIMS

Treatment with stereotactic radiosurgery/radiotherapy (SRS/SRT) is standard practice in selected patients with small numbers of brain metastases (BMs). It is less accepted in those with ≥5 BMs, due to the lack of a prospective evidence base. While randomised trials are ongoing, we present the experience of a single UK cancer centre in using SRS/SRT for patients with 5 or more BMs without whole brain radiotherapy (WBRT).

MATERIALS AND METHODS

Patients undergoing treatment at a single centre between 2014 and 2019 were prospectively identified. All follow-up imaging was reviewed to identify any evidence of local failure or distant brain progression, which was analysed using a death-censored approach.

RESULTS

A total of N = 88 patients were included, with a median of seven BMs (range: 5-37). Post-SRS/SRT toxicity events occurred in 42%, most commonly reliance on steroids for ≥4 weeks (36% of the cohort). Median survival was 10 months, with median freedom from local failure and distant brain progression of 12 and 8 months, respectively; none of these outcomes differed significantly by the number of BMs. Brain-directed salvage treatment was required after a median of 21 months, and was not significantly associated with the number of BMs.

CONCLUSION

SRS/SRT alone may have a role in the management of selected patients with multiple BMs. Since the number of BMs were not significantly associated with overall survival or disease control, the National Health Service (NHS) commissioning criteria should continue to be based on tumour volume.

Rethinking metastatic brain cancer as a CNS disease

Advances in molecular biology, genetics, and epigenetics have refined our understanding of metastatic brain cancer and underscored the need for better classification and targeted approaches. The heterogeneity of brain metastases highlights the differences from their primary source of origin and contributes to therapeutic resistance. Before colonising the brain, tumour cells acquire specialised proficiencies that enable them to capitalise on the unique microenvironment of the brain. The tumour cells further orchestrate key adaptations to adjust to the brain microenvironment by manipulating the blood-brain barrier, evading immune surveillance, rewiring metabolic profiles, and reprogramming astrocytes. These adaptations facilitate tumour survival, growth, and treatment resistance. Recognising metastatic brain cancer as a distinctive CNS disease, rather than an extension of the primary cancer, would support the development of rational approaches that target its molecular and genetic features and improve research funding in this area. Here, we delve into the distinct genetic and phenotypic characteristics of metastatic brain cancer, and reflect on how a change in the perception of this disease could accelerate the development of more effective therapies and drive continued progress in the field of neuro-oncology.

Survival and quality of life after first-time diagnosis of brain metastases: a multicenter, prospective, observational study

Background

A major concern in anticancer treatment (ACT) of brain metastases (BM) is exposing patients with short expected survival to treatments that negatively impact on quality of life (QoL). Such futile ACT at the end of life is time-consuming and burdensome for patients and their families and entails unnecessary healthcare costs. Refraining from ACT is challenging for both physicians and patients. This study aimed to provide real-life data on survival after BM diagnosis and patient reported outcomes (PROs) after ACT to identify risk factors for futile treatment and to support BM treatment decisions.

Methods

This multi-center, prospective, observational study recruited consecutive patients with first-time BM from November 2017 to March 2021. Patients were followed until death or study end (October 1st, 2023). Clinical factors associated with survival were analyzed by the Cox' proportional hazards model. Changes in PROs after BM treatment were described according to Eastern Cooperative Oncology Group (ECOG) performance status, survival, and treatment groups.

Findings

For the total cohort (N = 912), median overall survival (mOS) after BM diagnosis was 5.9 months (95% confidence interval [CI] 5.2-6.7). ECOG 2-4, uncontrolled extracranial metastases, and ≥5 BM were associated with short survival. In patients treated with radiotherapy, survival for patients with ECOG 2 and those with ECOG 3-4 was similar and particularly short for the whole brain radiotherapy (WBRT) group (ECOG 2: 2.9 months [95% CI 2.3-3.5]; ECOG 3-4: 2.1 [1.5-2.7]). Patients surviving <6 months after BM diagnosis reported worse QoL scores two months after ACT; patients surviving >6 months reported stable scores over time.

Interpretation

Patients with ECOG 2-4, especially those with uncontrolled extracranial metastases and ≥5 BM, are at risk for futile ACT. BM treatment guidelines should strongly caution against ACT to patients with expected survival <6 months and specifically advise against WBRT.

Funding

The South-Eastern Norway Regional Health Authority; The Norwegian Cancer Society.

Leptomeningeal metastatic disease: new frontiers and future directions

Leptomeningeal metastatic disease (LMD), encompassing entities of 'meningeal carcinomatosis', neoplastic meningitis' and 'leukaemic/lymphomatous meningitis', arises secondary to the metastatic dissemination of cancer cells from extracranial and certain intracranial malignancies into the leptomeninges and cerebrospinal fluid. The clinical burden of LMD has been increasing secondary to more sensitive diagnostics, aggressive local therapies for discrete brain metastases, and improved management of extracranial disease with targeted and immunotherapeutic agents, resulting in improved survival. However, owing to drug delivery challenges and the unique microenvironment of LMD, novel therapies against systemic disease have not yet translated into improved outcomes for these patients. Underdiagnosis and misdiagnosis are common, response assessment remains challenging, and the prognosis associated with this disease of whole neuroaxis remains extremely poor. The dearth of effective therapies is further challenged by the difficulties in studying this dynamic disease state. In this Review, a multidisciplinary group of experts describe the emerging evidence and areas of active investigation in LMD and provide directed recommendations for future research. Drawing upon paradigm-changing advances in mechanistic science, computational approaches, and trial design, the authors discuss domain-specific and cross-disciplinary strategies for optimizing the clinical and translational research landscape for LMD. Advances in diagnostics, multi-agent intrathecal therapies, cell-based therapies, immunotherapies, proton craniospinal irradiation and ongoing clinical trials offer hope for improving outcomes for patients with LMD.

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

Background

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

Methods

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

Results

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

Conclusion

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

Roles of SPOCK1 in the Formation Mechanisms and Treatment of Non-Small-Cell Lung Cancer and Brain Metastases from Lung Cancer

Lung cancer is a malignant tumor with high morbidity and mortality in China and worldwide. Once it metastasizes to the brain, its prognosis is very poor. Brain metastases are found in about 20% of newly diagnosed non-small-cell lung cancer (NSCLC) patients. About 30% of NSCLC patients develop brain metastases during treatment. NSCLC that is positive for EGFR, ALK, and ROS1 variations is especially likely to metastasize to the brain. SPOCK1 is a proteoglycan with systemic physiological functions. It regulates the self-renewal of brain metastasis-initiating cells, regulates invasion and metastasis from the lung to the brain, plays an important role in tumor progression and treatment resistance, and has higher expression in metastatic tumor tissues than other tissues. Current treatments for NSCLC brain metastases include surgery, whole-brain radiotherapy, stereotactic radiotherapy, targeted therapy, and chemotherapy. SPOCK1 is involved in many signaling pathways, by which it influences a variety of NSCLC treatment methods. In this paper, the progress of research on the treatment of NSCLC brain metastases is reviewed to guide decisions on treatment options in clinical practice.

Effects of EGFR-TKIs combined with intracranial radiotherapy in EGFR-mutant non-small cell lung cancer patients with brain metastases: a retrospective multi-institutional analysis

BACKGROUND

Patients with non-small cell lung cancer (NSCLC) are prone to developing brain metastases (BMs), particularly those with epidermal growth factor receptor (EGFR) mutations. In clinical practice, treatment-naïve EGFR-mutant NSCLC patients with asymptomatic BMs tend to choose EGFR-tyrosine kinase inhibitors (TKIs) as first-line therapy and defer intracranial radiotherapy (RT). However, the effectiveness of upfront intracranial RT remains unclear.

METHODS

This was a retrospective study including 217 patients from two institutions between January 2018 and December 2022. Clinical data of NSCLC patients with BMs who received EGFR-TKIs were collected. The patients were assigned to one of the three groups according to the therapeutic modality used: the upfront TKI + stereotactic radiosurgery (SRS) / fractionated stereotactic radiotherapy (fSRS) group (upfront TKI + SRS/fSRS ), the upfront TKI + whole-brain radiotherapy (WBRT) group (upfront TKI + WBRT) and the upfront TKI group.

RESULTS

As of March 8, 2023, the median follow-up duration was 37.3 months (95% CI, 32.5-42.1). The median overall survival (OS) for the upfront TKI + SRS/fSRS, upfront TKI + WBRT, and upfront TKI groups were 37.8, 20.7, and 24.1 months, respectively (p = 0.015). In subgroup analysis, the upfront TKI + SRS/fSRS group demonstrated longer OS compared to the upfront TKI + WBRT and upfront TKI groups in patients treated with first or second-generation EGFR-TKIs (p = 0.021) and patients with L858R mutation (p = 0.017), whereas no survival benefit was observed in three-generation EGFR-TKIs or 19del subgroup. In the multivariable analysis, metachronous BMs, EGFR L858R mutation and nonclassic EGFR mutation were identified as independent risk factors for OS, while a DS-GPA score of 2.0-4.0 was the only independent protective factor.

CONCLUSIONS

This study demonstrated that upfront addition of SRS/fSRS to EGFR-TKIs was associated with longer OS compared to upfront WBRT or upfront TKI alone in EGFR-mutant NSCLC patients with BMs. This improvement was more significant in patients with L858R mutation and those treated with first or second-generation EGFR-TKIs. Further research with a larger sample size is warranted.

Gadolinium-Enhanced T2 FLAIR Is an Imaging Biomarker of Radiation Necrosis and Tumor Progression in Patients with Brain Metastases

BACKGROUND AND PURPOSE

Differentiating radiation necrosis (RN) from tumor progression (TP) after radiation therapy for brain metastases is an important clinical problem requiring advanced imaging techniques that may not be widely available and are challenging to perform at multiple time points. The ability to leverage conventional MRI for this problem could have a meaningful clinical impact. The purpose of this study was to explore contrast-enhanced T2 FLAIR (T2FLAIRc) as a new imaging biomarker of RN and TP.

MATERIALS AND METHODS

This single-institution retrospective study included patients with treated brain metastases undergoing DSC-MRI between January 2021 and June 2023. Reference standard assessment was based on histopathology or serial follow-up, including the results of DSC-MRI for a minimum of 6 months from the first DSC-MRI. The index test was implemented as part of the institutional brain tumor MRI protocol and preceded the first DSC-MRI. T2FLAIRc and gadolinium-enhanced T1 (T1c) MPRAGE signal were normalized against normal brain parenchyma and expressed as a z score. The mean signal intensity of enhancing disease for the RN and TP groups was compared using an unpaired t test. Receiver operating characteristic curves and area under the receiver operating characteristic curve (AUC) were derived by bootstrapping. The DeLong test was used to compare AUCs.

RESULTS

Fifty-six participants (mean age, 62 [SD, 12.7] years; 39 women; 28 with RN, 28 with TP) were evaluated. The index MRI was performed, on average, 73 [SD, 34] days before the first DSC-MRI. Significantly higher z scores were found for RN using T2FLAIRc (8.3 versus 5.8, P < .001) and T1c (4.1 versus 3.5, P = .02). The AUC for T2FLAIRc (0.83; 95% CI, 0.72-0.92) was greater than that for T1c (0.70; 95% CI, 0.56-0.83) (P = .04). The AUC of DSC-derived relative CBV (0.82; 95% CI, 0.70-0.93) was not significantly different from that of T2FLAIRc (P = .9).

CONCLUSIONS

A higher normalized T1c and T2FLAIRc signal intensity was found for RN. In a univariable test, the mean T2FLAIRc signal intensity of enhancing voxels showed good discrimination performance for distinguishing RN from TP. The results of this work demonstrate the potential of T2FLAIRc as an imaging biomarker in the work-up of RN in patients with brain metastases.

Treatment Outcome of Brain Metastases from Breast Cancer Following Gamma Knife Radiosurgery: A Retrospective Study in Vietnam

BackgroundGamma Knife radiosurgery has proven to be highly effective for small brain lesions and those with a limited number of metastases. This study aimed to evaluate the treatment outcome of Gamma Knife radiosurgery in Vietnamese breast cancer patients with brain metastasis.MethodsThis retrospective descriptive study included 75 patients treated between January 2019 and December 2023. Eligible patients had 1 to 5 brain lesions ≤ 3 cm, a Karnofsky Performance Status (KPS) score of ≥ 60, and no prior whole-brain radiotherapy or brain tumor resection. Clinical characteristics were documented, and imaging responses were evaluated using RECIST criteria. Overall survival (OS), brain-specific progression-free survival (BSPFS), and overall response rates were analyzed using Kaplan-Meier survival curves and Cox regression.ResultsSeventy-five patients were included in the study, with a median follow-up time of 15.9 months. The median age was 53.0 years (range: 29-73 years), and 39 patients (52%) were HER2-positive. The median total tumor volume per patient was 3.78 cm3. A total of 152 brain tumors were identified, of which 131 (86.2%) were <2 cm in diameter, 36 patients (48.0%) had a single lesion. The intracranial tumor control rates were 96% at 3 months and 92.5% at 6 months. The median overall survival (OS) was 17.2 months (range: 13.7-20.7 months). Multivariate analysis revealed that the total volume of metastatic lesions ≤7.0 cm3, hormone receptor negativity, ≤ 3 lines of systemic treatment before brain metastasis and controlled extracranial metastases were correlated with both BSPFS and OS.ConclusionGamma Knife radiosurgery is an effective treatment for limited brain metastases, demonstrating a high rate of local control over brain lesions, which contributed to the promising survival outcome in Vietnamese breast cancer patients.

Distant brain failure after stereotactic radiosurgery for brain metastases in patients receiving novel systemic treatments

Background

Novel systemic therapies, such as immunotherapy and targeted therapies, have shown better systemic disease control in the last decennium. However, the effect of these treatments on distant brain failure (DBF) in patients with brain metastases (BM) remains a topic of discussion. Improving time to DBF leads to longer overall survival (OS), as is reflected in the brain metastasis velocity (BMV). This study presents real world data about the combined effects of local and systemic treatments on DBF and survival.

Methods

A retrospective consecutive cohort study was conducted. Patients with newly diagnosed BM were included between June 2018 and May 2020. Factors associated with DBF were analyzed in multivariate models. The association between BMV and overall survival was analyzed with linear regression analysis.

Results

Three hundred and three patients were included. Two hundred and sixty-two (86%) patients received stereotactic radiotherapy, 41 (14%) awaited in first instance the intracranial effect of newly started or switched systemic treatment. Median time to DBF after radiotherapy was 21 months (95% CI 15-27), median OS was 20 months (IQR 10-36). Receiving immunotherapy or targeted therapy were associated with a lower hazard of DBF, compared with chemotherapy. The presence of > 5 initial BM and progressive or stable extracranial disease were associated with increased DBF. BMV was significantly associated with overall survival.

Conclusions

In this retrospective cohort, patients who received immunotherapy or targeted therapy experienced a reduced risk of DBF in comparison to those treated with chemotherapy. A higher BMV was associated with a decreased OS.

Association between tumor location and toxicity outcomes after stereotactic radiosurgery for brain metastases

PURPOSE

Toxicities associated with stereotactic radiosurgery (SRS) are important when considering treatment and supportive management for patients with brain metastases. We herein assessed the association between brain metastasis location and risk of toxicity after SRS.

METHODS

We conducted a retrospective institutional review of patients treated with SRS for brain metastases between 2008 and 2023. Outcomes included radiation necrosis, seizure, local failure, and overall survival (OS).

RESULTS

We reviewed 215 patients treated to 605 metastases (median diameter 10 mm, IQR 5-17 mm), in the frontal (34%), cerebellar (19%), parietal (16%), temporal (13%), and occipital (13%) regions. Median follow-up was 16 months (IQR 7-36). New-onset seizures developed in 11% (19/174) of patients without prior seizure and was higher in patients with motor or sensory cortex lesions (12/48, 25%) on multivariate analysis (MVA, P = 0.02). SRS-related grade ≥ 2 symptomatic radionecrosis occurred in 6% (33/605) of lesions and correlated with larger metastasis volume (P < 0.001) and renal cell carcinoma histology (P < 0.05), while supratentorial location was nearly significant (MVA, P = 0.06). Median OS across all patients was 16 months (95% CI 12-20). Patients with symptomatic radiation necrosis had a longer median survival compared to those who did not (43 vs. 14 months, P = 0.002), which remained significant alongside Karnofsky performance status and extracranial disease on MVA.

CONCLUSION

Brain metastasis location in the motor or sensory cortex is associated with increased risk of new-onset seizure following SRS and may warrant consideration of steroid and/or anti-epileptic prophylaxis. Symptomatic radiation necrosis is uncommon in the cerebellum and may be increasing with improvements in survival.

Brain radiotherapy combined with camrelizumab and platinum-doublet chemotherapy for previously untreated advanced non-small-cell lung cancer with brain metastases (C-Brain): a multicentre, single-arm, phase 2 trial

BACKGROUND

Brain metastases are a common complication in patients with non-small-cell lung cancer (NSCLC) lacking actionable driver mutations, with limited treatment options and poor prognosis. We aimed to investigate the efficacy and safety of brain radiotherapy combined with camrelizumab and platinum-doublet chemotherapy in patients with newly diagnosed advanced NSCLC and brain metastases.

METHODS

This multicentre, single-arm, phase 2 trial was done across nine tertiary hospitals in China. Eligible patients were aged 18 years or older, had newly diagnosed brain metastases from NSCLC with no actionable driver mutations (EGFR, ALK, or ROS1), and had an Eastern Cooperative Oncology Group performance status of 0 or 1. Eligible patients were treated with stereotactic radiosurgery or whole-brain radiotherapy combined with camrelizumab (200 mg intravenously once every 3 weeks) and investigator-selected platinum-doublet chemotherapy (pemetrexed 500 mg/m2 plus platinum [carboplatin, area under curve (AUC) of 5, or cis-platinum 75 mg/m2] for non-squamous NSCLC, and nab-paclitaxel 260 mg/m2 plus platinum [carboplatin AUC 5, or cis-platinum 75 mg/m2] for squamous NSCLC) for four to six cycles. Patients with controlled disease then received maintenance treatment with camrelizumab alone (200 mg intravenously once every 3 weeks; for squamous NSCLC) or camrelizumab plus pemetrexed (500 mg/m2 every 3 weeks; for non-squamous NSCLC). The primary endpoint was 6-month progression-free survival rate in the full analysis set, which included all patients who received at least one dose of study treatment regardless of whether they had measurable brain lesions per RECIST 1.1. The trial was registered with ClinicalTrials.gov, NCT04291092, and is ongoing.

FINDINGS

Between May 6, 2020, and Jan 30, 2023, 67 patients were assessed for eligibility. Two patients were excluded (brain lesions less than 5 mm) and 65 patients were enrolled and treated. Median age was 66 years (IQR 62-70). 60 (92%) of 65 patients were male and five (8%) were female. All 65 patients were Han Chinese. 50 (77%) of 65 patients had non-squamous NSCLC and 46 (71%) were symptomatic. The 6-month progression-free survival rate was 71·7% (95% CI 58·9-81·1) during the median follow-up of 14·1 months (IQR 9·0-20·3; data cutoff Dec 13, 2023). The most common grade 3-4 treatment-related adverse events were decreased neutrophil count (14 [22%] of 65 patients), decreased white blood cell count (ten [15%]), decreased platelet count (ten [15%]), and decreased lymphocyte count (nine [14%]). Neurological toxic effects of grade 3 occurred in three (5%) of 65 patients. Radiation necrosis occurred in three (5%) of 65 patients; all were grade 1 or 2. There were no treatment-related deaths.

INTERPRETATION

Brain radiotherapy combined with camrelizumab and platinum-doublet chemotherapy shows promising efficacy and manageable toxicity and could be a potential treatment option for patients with brain metastases from NSCLC. Randomised controlled trials will be required to confirm these findings.

FUNDING

Beijing Xisike Clinical Oncology Research Foundation and Jiangsu Hengrui Pharmaceuticals.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

Upfront Stereotactic Radiosurgery or Fractionated Stereotactic Radiotherapy in Elderly Patients with Brain Metastases from Non-Small Cell Lung Cancer: A Retrospective Analysis of a 10-Year Bi-institutional Experience

PURPOSE

Stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) are increasingly used as initial therapies for brain metastases (BM). We aimed to assess the outcomes of SRS/FSRT in patients aged ≥ 65 years who had 1-10 BM from non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

We retrospectively reviewed 91 elderly NSCLC patients with 222 BM who were treated with SRS/FSRT at two institutions between 2010 and 2020. The primary endpoint was overall survival (OS) after SRS/FSRT. In addition, in-field local control (IFLC) within the treated field was evaluated. Statistical analysis was performed to identify the prognostic factors affecting OS and IFLC.

RESULTS

During a median follow-up of 18 months, the median OS was 32 months. The 1- and 2-year survival rates were 69.8% and 56.1%, respectively. In multivariate analysis, the NSCLC-specific graded prognostic assessment (GPA) score (p=0.007) and administration of systemic therapy (p=0.039) were defined as prognosticators affecting OS. The median IFLC period was 31 months, and the 1- and 2-year IFLC rates were 75.9% and 57.6%, respectively. The total BM volume (p=0.042) significantly affected IFLC. No severe adverse events were reported after SRS/FSRT.

CONCLUSION

SRS/FSRT is an effective upfront treatment option for BM arising from NSCLC in elderly patients, with a good OS without severe side effects. Higher GPA score and active systemic treatment were associated with improved OS, indicating that elderly patients are significant candidates for SRS/FSRT.

Clinical Outcomes and Relevance of Composite V12 Gy in Patients With Four or More Brain Metastases Treated With Single Fraction Stereotactic Radiosurgery

AIMS

Tissue V12Gy (total brain volume receiving 12Gy including target) can predict for late toxicity in single target benign disease treated with stereotactic radiosurgery (SRS). The value of this metric remains uncertain for multiple brain metastases. This retrospective cohort study reports the outcomes and evaluates the predictors of toxicity in patients with four or more brain metastases treated with single-fraction SRS.

MATERIALS AND METHODS

Two hundred twenty-six patients with 2160 metastases treated from 2014-21 were retrospectively studied. Symptomatic late toxicity (new/progressive neurological symptoms ≥3 months post SRS) with magnetic resonance imaging (MRI) changes suggestive of treatment effect were analysed. Kaplan-Meier and competing risk analysis was used to assess survival and toxicity respectively.

RESULTS

median number of metastases/patient was 6 (range: 4-41) and median composite tissue V12Gy (inclusive of planning target volume (PTV)) was 11.3 cc (IQR: 6.1 cc-17.1 cc). Sixteen out of the 226 patients developed symptomatic late radiation adverse event (R-AE), and the cumulative incidence was 4.9% at 1 year and 6.9% at 2 years. The total target volume was significantly predictive of the risk of late R-AE. Volume of the largest lesion, V12Gy and V15Gy did not predict for late R-AE, but plotted graphs showed suggestions of linear relationships between dosimetric parameters and late R-AE.

CONCLUSION

Within the limitations of this study, the cumulative incidence of symptomatic toxicity remains acceptable despite routinely accepting a composite tissue V12Gy in excess of 10 cc to treat multiple brain metastases.

ADVANCES IN KNOWLEDGE

V12Gy has limitations as a plan quality metric in multiple brain metastases treated with SRS. There is insufficient evidence to have a defined target limit as <10 cc.

Evaluation of Anti-Angiogenic Therapy Combined with Immunotherapy and Chemotherapy as a Strategy to Treat Locally Advanced and Metastatic Non-Small-Cell Lung Cancer

Immunotherapy has made recent improvements in disease-free survival (DFS) and/or overall survival (OS) in all stages of non-small-cell lung cancer (NSCLC). Here, we review the tumor microenvironment and its immunosuppressive effects and discuss how anti-angiogenic therapies may potentiate the anti-carcinogenic effects of immunotherapy. We also review all the past literature and discuss strategies of combining anti-angiogenic therapy and immunotherapy +/- chemotherapy and hypothesize how we can use this strategy for non-small-cell lung cancer in metastatic previously untreated/previously treated settings in previously treated EGFR-mutated NSCLC for the upfront treatment of brain metastases prior to radiation therapy and for the incorporation of this strategy into stage III unresectable disease. We assert the use of anti-angiogenic therapy and immunotherapy when combined appropriately with chemotherapy and radiotherapy has the potential to increase the long-term survivals in both the stage III and metastatic setting so that we can now consider more patients to experience curative treatment.

Lung Cancer with Brain Metastasis-Treatment Strategies and Molecular Characteristics

Lung cancer is a leading cause of brain metastases (BMs), with 10-20% of patients with non-small cell lung cancer (NSCLC) presenting with BMs at diagnosis and 25-50% developing them over the course of their disease. Historically, BMs have posed significant therapeutic challenges, partly due to the blood brain barrier (BBB), which restricts drug penetration to the central nervous system. Consequently, BMs were initially managed with local treatments, including surgical resection, stereotactic radiosurgery, and whole brain radiation therapy. In recent years, however, systemic treatments for BMs have advanced significantly, particularly with the development of molecularly-targeted therapies and immunotherapies. The discovery of driver mutations and the development of novel tyrosine kinase inhibitors (TKIs) have yielded encouraging intracranial responses in NSCLC patients with actionable genetic alterations (e.g., EGFR, ALK, ROS1). Genomic profiling has also suggested genetic heterogeneity between BMs and primary sites. Immunotherapies, alone or in combination with other treatments, have demonstrated promising results in NSCLC with BMs, although most clinical trials have included only selected patients with asymptomatic or previously treated BMs. In this review, we discuss the molecular and immune characteristics of NSCLC with BMs, analyze intracranial efficacy findings from clinical trials, and explore treatment strategies for lung cancer patients with BMs.

Effect of neutron beam properties on dose distributions in a water phantom for boron neutron capture therapy

From the viewpoints of the advantage depths (ADs), peak tumor dose and skin dose, we evaluated the effect on the dose distribution of neutron beam properties, namely the ratio between thermal and epithermal neutron fluxes (thermal/epithermal ratio), fast neutron component and γ-ray component. Several parameter surveys were conducted with respect to the beam properties of neutron sources for boron neutron capture therapy assuming boronophenylalanine as the boron agent using our dose calculation tool, called SiDE. The ADs decreased by 3% at a thermal/epithermal ratio of 20-30% compared with the current recommendation of 5%. The skin dose increased with the increasing thermal/epithermal ratio, reaching a restricted value of 14 Gyeq at a thermal/epithermal ratio of 48%. The fast neutron component was modified using two different models, namely the 'linear model', in which the fast neutron intensity decreases log-linearly with the increasing neutron energy, and the 'moderator thickness (MT) model', in which the fast neutron component is varied by adjusting the MT in a virtual beam shaping assembly. Although a higher fast neutron component indicated a higher skin dose, the increment was <10% at a fast neutron component of <1 × 10-12 Gy cm2 for both models. Furthermore, in the MT model, the epithermal neutron intensity at a fast neutron component of 6.8 × 10-13 Gy cm2 was 41% higher compared with that of 2 × 10-13 Gy cm2. The γ-ray component also caused no significant disadvantages up to several times larger compared with the current recommendation.

Atypical Cerebral Carcinoids Treated with Hippocampal-Sparing Whole Brain Radiotherapy

Central nervous system (CNS) metastases of atypical carcinoid tumors are exceptionally rare. Isolated studies suggest a survival benefit in patients who receive whole-brain radiotherapy (WBRT); however, it has been known to have detrimental effects on long-term memory and executive function. Here, we present a case of a patient initially diagnosed with stage IIB bronchopulmonary carcinoid who later developed hepatic and intracranial metastases despite receiving adjuvant systemic therapy over a two-year period. She underwent hippocampal-sparing WBRT (HS-WBRT), receiving 30 Gy in 10 fractions via daily image-guided photon therapy using two coplanar arcs. Subsequent clinical evaluations and magnetic resonance imaging (MRI) of the brain at 11 months post-treatment demonstrated a decrease in the size and number of brain metastases, with the patient reporting stable memory and cognition. This case demonstrates the efficacious delivery of palliative HS-WBRT in a patient with a rare presentation of brain-metastatic atypical carcinoid, conferring effective local control and preservation of cognition. Multi-therapy regimens that incorporate HS-WBRT may be considered for improved disease control and quality of life. Further investigation of systemic agents, and possible molecular targets that could confer greater efficacy against treatment-progressive atypical carcinoids, is also warranted.

Advancements and challenges in brain cancer therapeutics

Treating brain tumors requires a nuanced understanding of the brain, a vital and delicate organ. Location, size, tumor type, and surrounding tissue health are crucial in developing treatment plans. This review comprehensively summarizes various treatment options that are available or could be potentially available for brain tumors, including physical therapies (radiotherapy, ablation therapy, photodynamic therapy, tumor-treating field therapy, and cold atmospheric plasma therapy) and non-physical therapies (surgical resection, chemotherapy, targeted therapy, and immunotherapy). Mechanisms of action, potential side effects, indications, and latest developments, as well as their limitations, are highlighted. Furthermore, the requirements for personalized, multi-modal treatment approaches in this rapidly evolving field are discussed, emphasizing the balance between efficacy and patient safety.

Progress of intracranial metastases during the interval before stereotactic radiosurgery, a retrospective cohort analysis

INTRODUCTION

The incidence of intracranial metastatic disease is increasing worldwide. As a valuable treatment modality, stereotactic radiosurgery requires detailed imaging, and this study evaluated the differences between imaging obtained on the day of treatment compared to historical or referral imaging.

MATERIALS AND METHODS

A retrospective cohort study was performed, evaluating all the patients presenting with eligible referral imaging in a 13-month period and comparing this imaging to the imaging taken on the day of treatment. Numbers of additional metastases, volumes and volume differences among the images were compared.

RESULTS

There was a median interval of 19 days between the acquisition of the diagnostic or referral scan and the day of treatment imaging. Even the group that had the shortest interval (up to 2 weeks) showed at least one additional deposit in 50 % of the patients. Volume was increased in 75 % of this group. Longer intervals were associated with higher increases in volume.

CONCLUSION

These results demonstrate the increase in the disease burden in patients with intracranial metastatic disease, in relation to number and volume, in the interval between the referral and treatment imaging. This has significant implications for planning pathways, to ensure that metastatic deposits are not missed or undertreated.

Radiotherapy in patients with brain metastases with and without concomitant immunotherapy: comparison of patient outcome and neurotoxicity

BACKGROUND/AIM

Recently, immune checkpoint inhibitors (ICI) have been added to the treatment of brain metastases. While combining radiotherapy and ICI can enhance therapeutic effects, it might also increase the risk of severe autoimmune adverse events. This retrospective study aims to compare treatment responses and neurotoxicity in patients treated with radiotherapy alone versus those receiving a combination of radiotherapy and ICI.

PATIENTS AND METHODS

All patients with brain metastases who received radiotherapy at Hannover Medical School from 2017 to 2019 were included. The medical reports of all study participants were evaluated. Patients who received radiotherapy alone and those who received a combination of radiation and ICI were compared.

RESULTS

A total of 248 patients were analyzed, with the most common tumor types being non-small cell lung cancer (NSCLC) and malignant melanoma. Half of the patients received whole-brain radiotherapy (WBRT) and the other half stereotactic radiotherapy (SRT). Of these, 29 patients received concurrent immunotherapy and radiotherapy, 30 completed immunotherapy before radiotherapy, and 29 started ICI after completing radiotherapy. Two cases lacked information on the duration of immunotherapy. Overall survival post-initial tumor diagnosis within the total cohort was 52 months, with significantly worse survival for patients with multiple brain metastases (p = 0.020). No significant differences in survival or incidence of neurological adverse events were observed between patients with or without ICI.

CONCLUSION

Combining radiotherapy and ICI did not significantly increase neurotoxicity or improve survival in this cohort, though the heterogeneity of the subgroups limits the generalizability of these findings.

Advances in the Management of Lung Cancer Brain Metastases

Lung cancer, both non-small cell and small cell, harbors a high propensity for spreading to the central nervous system. Radiation therapy remains the backbone of the management of brain metastases. Recent advances in stereotactic radiosurgery have expanded its indications and ongoing studies seek to elucidate optimal fractionation and coordination with systemic therapies, especially targeted inhibitors with intracranial efficacy. Efforts in whole-brain radiotherapy aim to preserve neurocognition and to investigate the need for prophylactic cranial irradiation. As novel combinatorial strategies are tested and prognostic/predictive biomarkers are identified and tested, the management of brain metastases in lung cancer will become increasingly personalized to optimally balance intracranial efficacy with preserving neurocognitive function and patient values.

Brain metastases reirradiation

The advances in cancer screening and therapies have allowed the improvement of metastatic patients' survival, including those with brain metastases. This led to a substantial shift in brain metastases patients' management for whom whole-brain radiation therapy, formerly widely used, has given way to a more focused management in which single- or multifractionated stereotactic radiation therapy now plays a predominant role. Although stereotactic radiation therapy offers excellent local control rates (70 to 90%), it does not prevent brain recurrence outside the radiation field, which is all the more frequent the higher the number of initial metastases and the longer the patient's survival. In the case of brain recurrence after irradiation, therapeutic options will depend both on the previous treatment and on the features of the recurrence. This article aims to review the available data on the efficacy and tolerability of various reirradiation schemes in different clinical situations.

Selection criteria for circular collimator- vs. Multileaf collimator-based plans in robotic stereotactic radiotherapy for brain metastases and benign intracranial disease: Impact of target size, shape complexity, and proximity to at-risk organs

PURPOSE

This study aimed to determine the selection criteria for circular collimator (CC)- and multileaf collimator (MLC)-based stereotactic radiosurgery (SRS)/stereotactic radiotherapy (SRT) plans for brain metastases (BM) and benign intracranial disease (BID) in terms of geometric parameters using CyberKnife (CK).

METHODS

Forty-eight and eighty-five patients with BM and BID, respectively, were included. Two plans using CC and MLC were created for each case. Six dosimetric parameters and mathematical scores (MS) were extracted from each plan to assess plan quality. Two geometric parameters in BM-equivalent radius (rGTV) and sphericity index (SI) of the gross tumor volume-and three in BID-rGTV, SI, and the distance between the GTV and organ at risk (dOAR)-were calculated. Their effect on the superiority of CC- or MLC-based plans in terms of dosimetric parameters and MS was evaluated using multiple regression analysis.

RESULTS

The rGTV was associated with improved dosimetric parameters of MLC-based plans, especially the GTV conformity in BM and BID cases (β: 0.70 and 0.51) and the OAR sparing in BM cases (β: 0.82), where β represents the regression coefficient. Based on the MS, where the weights for the GTV coverage and OAR sparing were equal, the thresholds at which the MLC-based plans become comparable or superior to the CC-based plans in BM and BID were rGTV > 7.6 and >17.5 mm, respectively. Meanwhile, SI and dOAR were weakly correlated (β ≤ 0.30).

CONCLUSIONS

In SRS/SRT plans for BM and BID cases using CyberKnife, geometric parameters, especially rGTV, must be considered when selecting CC or MLC.

Effective Personalization of Stereotactic Radiosurgery for Brain Metastases in the Modern Era: Opportunities for Innovation

ABSTRACT

As survival rates improve for patients with metastatic disease, more patients are requiring complex treatment for brain metastases. Stereotactic radiosurgery (SRS) is a conformal radiotherapy technique that allows high ablative dose to be delivered to a specific target and is a standard effective local therapy for the treatment of patients with limited brain metastases. This review highlights the current landscape of SRS treatment in the context of modern therapeutic advances and identifies new research frontiers to personalize SRS and maximize the therapeutic ratio.

Treatment of brain metastases from non-small cell lung cancer: preclinical, clinical, and translational research

Lung cancer is the second most common type of cancer and is the leading cause of cancer-related deaths in the United States. Approximately 10-40% of patients with solid tumors develop brain metastases, with non-small cell lung cancer accounting for approximately 50% of all cases of patients with brain metastases. Many management options are available which can include surgery, radiation, and systemic therapy. A variety of factors go into the selection of management of brain metastases. In this review, we will focus on the treatment strategies and optimizing the management of brain metastases in patients with non-small cell lung cancer.

Tyrosine Kinase Inhibitors With and Without Up-Front Stereotactic Radiosurgery for Brain Metastases From EGFR and ALK Oncogene-Driven Non-Small Cell Lung Cancer (TURBO-NSCLC)

PURPOSE

Newer-generation tyrosine kinase inhibitors (TKIs) for non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements have demonstrated high CNS activity. The optimal use of up-front stereotactic radiosurgery (SRS) for brain metastases (BM) in patients eligible for CNS-penetrant TKIs is controversial, and data to guide patient management are limited.

MATERIALS AND METHODS

Data on TKI-naïve patients with EGFR- and ALK-driven NSCLC with BM treated with CNS-penetrant TKIs with and without up-front SRS were retrospectively collected from seven academic centers in the United States. Time-to-CNS progression and overall survival (OS) were analyzed, with multivariable adjustment in Fine & Gray and Cox proportional hazards models for clinically relevant factors.

RESULTS

From 2013 to 2022, 317 patients were identified (200 TKI-only and 117 TKI + SRS). Two hundred fifty (79%) and 61 (19%) patients received osimertinib and alectinib, respectively. Patients receiving TKI + SRS were more likely to have BM ≥1 cm (P < .001) and neurologic symptoms (P < .001) at presentation. Median OS was similar between the TKI and TKI + SRS groups (median 41 v 40 months, respectively; P = .5). On multivariable analysis, TKI + SRS was associated with a significant improvement in time-to-CNS progression (hazard ratio [HR], 0.63 [95% CI, 0.42 to 0.96]; P = .033). Local CNS control was significantly improved with TKI + SRS (HR, 0.30 [95% CI, 0.16 to 0.55]; P < .001), whereas no significant differences were observed in distant CNS control. Subgroup analyses demonstrated a greater benefit from TKI + SRS in patients with BM ≥1 cm in diameter for time-to-CNS progression and CNS progression-free survival.

CONCLUSION

The addition of up-front SRS to CNS-penetrant TKI improved time-to-CNS progression and local CNS control, but not OS, in patients with BM from EGFR- and ALK-driven NSCLC. Patients with larger BM (≥1 cm) may benefit the most from up-front SRS.

Patterns of Care for Brain Metastases in Asia: A Real-World Survey Conducted by the Federation of Asian Organizations for Radiation Oncology

PURPOSE

To report the patterns of care for brain metastases (BMs) in the Federation of Asian Organizations for Radiation Oncology (FARO).

METHODS

Overall, 37 questions were prepared. The survey was conducted online using Google Forms, and the URL was distributed to members of the FARO research committee. Radiation oncologists associated with FARO responded to the questionnaire between May 2023 and June 2023, and their answers were analyzed.

RESULTS

Responses were received from 32 radiation oncologists in 13 countries participating in FARO. Twenty-six physicians (81.3%) were affiliated with academic centers, and 22 (68.8%) were able to perform stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (fSRT) for BMs at their institution. The most typically used prognostic index for BM was the recursive partitioning analysis classification (17 physicians, 53.1%). The maximum number of BMs indicated for SRT/SRS was ≤three (11 physicians, 34.4%), whereas eight (25.0%) physicians answered for 6-10 BMs. The maximum size of BMs considered for SRS/fSRT was ≤3 cm (14 physicians, 43.8%), whereas nine (28.1%) answered that SRS/fSRT was preferred if the maximum size was >4 cm. When whole-brain radiotherapy (RT) was indicated, hippocampal avoidance and memantine usage were limited to 50.0% and 25.0% of patients, respectively. The most typical RT modality after BM resection was SRS/fSRT alone, regardless of whether the margin was positive (19 physicians, 59.4%) or negative (13 physicians, 40.6%).

CONCLUSION

We report the survey results of the patterns of care for BMs in the FARO. This survey was conducted only among a limited number of FARO members. Since many respondents were affiliated with relatively large-scale academic centers, large-scale surveys, including community hospitals, are warranted for future initiatives.

Breast Cancer Brain Metastasis: A Comprehensive Review

The mechanisms underlying breast cancer brain metastasis (BCBM) development are complex, and its clinical presentation varies depending on the number, location, and size of brain metastases. Common symptoms include headache, neurologic deficits, and seizures. Diagnosis of BCBM typically relies on neuroimaging techniques, such as magnetic resonance imaging and computed tomography scans. Local therapies, such as surgery and stereotactic radiosurgery, can be used to control tumor growth and relieve symptoms. Whole-brain radiotherapy has been a mainstay of treatment for BCBM, but its use has been associated with cognitive decline. Systemic therapy with chemotherapy and targeted agents plays an increasingly important role in the management of BCBM. Novel agents, such as human epidermal growth factor receptor 2 (HER2)-targeted therapies and tyrosine kinase inhibitors, have shown promising results in improving survival for patients with HER2-positive and triple-negative BCBM. This comprehensive review synthesizes current knowledge, clinical insights, and evolving paradigms to provide a robust understanding and roadmap for optimizing the diagnosis and management of BCBM.

Comparative effectiveness of frame-based and mask-based Gamma Knife stereotactic radiosurgery in brain metastases: A 509 patient meta-analysis

PURPOSE

Stereotactic Radiosurgery (SRS) is the primary treatment for patients with limited numbers of small brain metastases. Head fixation is usually performed with framed-based (FB) fixation; however, mask-based (MB) fixation has emerged as a less invasive alternative. A comparative meta-analysis between both approaches has not been performed.

METHODS

Databases were searched until August 28th, 2023, to identify studies comparing MB and FB SRS in the treatment of brain metastases. Our outcomes of interest included local tumor control (LTC), radiation necrosis (RN), mortality, and treatment time (TT). Mean difference (MD), risk ratio (RR), and hazard ratio (HR) were used for statistical comparisons.

RESULTS

From 295 articles initially identified, six studies (1 clinical trial) involving 509 patients were included. LTC revealed comparable RR at 6-months (RR = 0.95[95%CI = 0.89-1.01], p = 0.12) and a marginal benefit in FB SRS at 1-year (RR = 0.87[95%CI = 0.78-0.96], p = 0.005). However, in oligometastases exclusively treated with single-fraction SRS, LTC was similar among groups (RR = 0.92 [95%CI = 0.89-1.0], p = 0.30). Similarly, in patients with oligometastases treated with single-fraction SRS, RN (HR = 1.69; 95%CI = 0.72-3.97, p = 0.22), TT (MD = -29.64; 95%CI = -80.38-21.10, p = 0.25), and mortality were similar among groups (RR = 0.62; 95%CI = 0.22-1.76, p = 0.37).

CONCLUSION

Our findings suggest that FB and MB SRS, particularly oligometastases treated with single-fraction, are comparable in terms of LTC, RN, TT, and mortality. Further research is essential to draw definitive conclusions.

Prioritizing Radiation and Targeted Systemic Therapies in Patients with Resected Brain Metastases from Lung Cancer Primaries with Targetable Mutations: A Report from a Multi-Site Single Institution

Background/Objectives: Brain metastases (BrMs) are a common complication of non-small cell lung cancer (NSCLC), present in up to 50% of patients. While the treatment of BrMs requires a multidisciplinary approach with surgery, radiotherapy (RT), and systemic therapy, the advances in molecular sequencing have improved outcomes in patients with targetable mutations. With a push towards the molecular characterization of cancers, we evaluated the outcomes by treatment modality at our institution with respect to prioritizing RT and targeted therapies. Methods: We identified the patients with NSCLC BrMs treated with surgical resection. The primary endpoints were in-brain freedom from progression (FFP) and overall survival (OS). The secondary endpoint included index lesion recurrence. The tumor molecular profiles were reviewed. The outcomes were evaluated by treatment modality: surgery followed by adjuvant RT and/or adjuvant systemic therapy. Results: In total, 155/272 (57%) patients who received adjuvant therapy with adequate follow-up were included in this analysis. The patients treated with combination therapy vs. monotherapy had a median FFP time of 10.72 months vs. 5.38 months, respectively (p = 0.072). The patients of Hispanic/Latino vs. non-Hispanic/Latino descent had a statistically significant worse OS of 12.75 months vs. 53.15 months, respectively (p = 0.015). The patients who received multimodality therapy had a trend towards a reduction in index lesion recurrences (χ2 test, p = 0.063) with a statistically significant improvement in the patients receiving immunotherapy (χ2 test, p = 0.0018). Conclusions: We found that systemic therapy combined with RT may have an increasing role in delaying the time to progression; however, there was no statistically significant relationship between OS and treatment modality.

Longitudinal deep neural networks for assessing metastatic brain cancer on a large open benchmark

The detection and tracking of metastatic cancer over the lifetime of a patient remains a major challenge in clinical trials and real-world care. Advances in deep learning combined with massive datasets may enable the development of tools that can address this challenge. We present NYUMets-Brain, the world's largest, longitudinal, real-world dataset of cancer consisting of the imaging, clinical follow-up, and medical management of 1,429 patients. Using this dataset we developed Segmentation-Through-Time, a deep neural network which explicitly utilizes the longitudinal structure of the data and obtained state-of-the-art results at small (<10 mm3) metastases detection and segmentation. We also demonstrate that the monthly rate of change of brain metastases over time are strongly predictive of overall survival (HR 1.27, 95%CI 1.18-1.38). We are releasing the dataset, codebase, and model weights for other cancer researchers to build upon these results and to serve as a public benchmark.

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.

De novo versus recurrent metastatic breast cancer affects the extent of brain metastases

PURPOSE

We aimed to identify factors associated with the extent of brain metastases in patients with breast cancer to help distinguish brain oligometastases (1-4 brain metastases) from extensive metastases (5 or more brain metastases).

METHODS

This retrospective observational study included 100 female patients diagnosed with brain metastases from breast cancer at a single institution between January 2011 and April 2022. Patient demographics and tumor characteristics were compared between the brain oligometastases group and the extensive metastases group. Multivariable logistic regression analysis was performed to determine the independent factors, including age at initial diagnosis, initial stage, breast cancer subtype, detection time of brain metastases, and de novo or recurrent status of the metastatic disease. In a subgroup analysis of patients with brain oligometastases, demographic and tumor characteristics were compared between patients with single and two-four brain metastases.

RESULTS

Of the 100 patients, 56 had brain oligometastases, while 44 had extensive brain metastases. The multivariable logistic regression analysis revealed that only the de novo/recurrent status of metastatic breast cancer was significantly associated with the extent of brain metastasis (p = 0.023). In the subgroup analysis of 56 patients with brain oligometastases, those diagnosed at an earlier stage were more likely to have a single brain metastasis (p = 0.008).

CONCLUSION

Patients with de novo metastatic breast cancer are more likely to develop extensive brain metastases than those with recurrent metastatic breast cancer. This insight could influence the development of tailored approaches for monitoring and treating brain metastases, supporting the potential advantages of routine brain screening for patients newly diagnosed with stage IV breast cancer.

The Emerging Role of Immune Checkpoint Blockade for the Treatment of Lung Cancer Brain Metastases

Lung cancer has the highest incidence of brain metastases (BM) among solid organ cancers. Traditionally whole brain radiation therapy has been utilized for non-small-cell lung cancer (NSCLC) BM treatment, although stereotactic radiosurgery has emerged as the superior treatment modality for most patients. Highly penetrant central nervous system (CNS) tyrosine kinase inhibitors have also shown significant CNS activity in patients harboring select oncogenic drivers. There is emerging evidence that patients without oncogene-driven tumors derive benefit from the use of immune checkpoint inhibitors (ICIs). The CNS activity of ICIs have not been well studied given exclusion of patients with active BM from landmark trials, due to concerns of inadequate CNS penetration and activity. However, studies have challenged the idea of an immune-privileged CNS, given the presence of functional lymphatic drainage within the CNS and destruction of the blood brain barrier by BM. An emerging understanding of the interactions between tumor and CNS immune cells in the BM tumor microenvironment also support a role for immunotherapy in BM treatment. In addition, posthoc analyses of major trials have shown improved intracranial response and survival benefit of regimens with ICIs over chemotherapy (CT) alone for patients with BM. Two prospective phase 2 trials evaluating pembrolizumab monotherapy and atezolizumab plus CT in patients with untreated NSCLC BM also demonstrated significant intracranial responses. This review describes the interplay between CNS immune cells and tumor cells, discusses current evidence for ICI CNS activity from retrospective and prospective studies, and speculates on future directions of investigation.

Single versus multiple fraction stereotactic radiosurgery for medium-sized brain metastases (4-14 cc in volume): reducing or fractionating the radiosurgery dose?

Background and purpose

Stereotactic radiosurgery (SRS) of brain metastases (BM) and resection cavities is a widely used and effective treatment modality. Based on target lesion size and anatomical location, single fraction SRS (SF-SRS) or multiple fraction SRS (MF-SRS) are applied. Current clinical recommendations conditionally recommend either reduced dose SF-SRS or MF-SRS for medium-sized BM (2-2.9 cm in diameter). Despite excellent local control rates, SRS carries the risk of radionecrosis (RN). The purpose of this study was to assess the 12-months local control (LC) rate and 12-months RN rate of this specific patient population.

Materials and methods

This single-center retrospective study included 54 patients with medium-sized intact BM (n=28) or resection cavities (n=30) treated with either SF-SRS or MF-SRS. Follow-up MRI was used to determine LC and RN using a modification of the "Brain Tumor Reporting and Data System" (BT-RADS) scoring system.

Results

The 12-month LC rate following treatment of intact BM was 66.7% for SF-SRS and 60.0% for MF-SRS (p=1.000). For resection cavities, the 12-month LC rate was 92.9%% after SF-SRS and 46.2% after MF-SRS (p=0.013). For intact BM, RN rate was 17.6% for SF-SRS and 20.0% for MF-SRS (p=1.000). For resection cavities, RN rate was 28.6% for SF-SRS and 20.0% for MF-SRS (p=1.000).

Conclusion

Patients with intact BM showed no statistically significant differences in 12-months LC and RN rate following SF-SRS or MF-SRS. In patients with resection cavities the 12-months LC rate was significantly better following SF-SRS, with no increase in the RNFS.

The effect of time-delayed contrast-enhanced scanning in determining the gross tumor target volume of large-volume brain metastases

BACKGROUND AND PURPOSE

To assess the variation of large-volume brain metastases (BMs) boundaries and shapes using enhanced magnetic resonance (MR) scanning with different delay times and to provide a basis for determining the gross tumor target volume (GTV) for radiotherapy of BMs.

MATERIALS AND METHODS

We prospectively enrolled 155 patients initially diagnosed with BMs (561 lesions > 1 cm). Contrast-enhanced (CE) T1-weighted imaging scans were performed 1, 3, 5, 10, 18, and 20 min after gadolinium-based contrast agent injection and GTVs were determined as GTV-1min, GTV-3min, GTV-5min, GTV-10min, GTV-18min, and GTV-20min, respectively, which were subsequently fused in different phases. Fusion of the six GTVs was defined as GTV-total, which was set as the reference GTV. The volume, shape, and signal intensity of the GTVs and brain white matter (BWM) were compared at different delay times.

RESULTS

GTV-3min, GTV-5min, GTV-10min, GTV-18min, and GTV-20min volumes increased by 2.2 %, 3.8 %, 6.5 %, 9.5 %, and 10.6 %, respectively (P < 0.05) compared with GTV-1min. Compared with GTV-total, GTV-1min, GTV-3min, GTV-5min, GTV-10min, GTV-18min, and GTV-20min volumes reduced by 25.4 %, 22.1 %, 18.7 %, 15.0 %, 11.2 %, and 10.3 %, respectively (P < 0.05). Compared with GTV-total, 29 (51.8 %) fused GTVs had a volume reduction rate < 5 %, 45 (80.4 %) had a Dice similarity coefficient > 0.95, and all contained GTV-10min, GTV-18min or GTV-20min. The signal intensity ratio between the GTV and BWM peaked at 5 min (0.351 ± 0.24).

CONCLUSION

Enhanced MR scans with different delay times show significant differences in the boundaries and shapes of large-volume BMs, and time-delayed multi-phase CE scanning should be used in GTV determination, with time phases ≥ 10 min being mandatory.