Stereotactic radiosurgery for patients with multiple brain metastases (JLGK0901): a multi-institutional prospective observational study

Total brain dose estimation in single-isocenter-multiple-targets (SIMT) radiosurgery via a novel deep neural network with spherical convolutions

BACKGROUND AND PURPOSE

Accurate prediction of normal brain dosimetric parameters is crucial for the quality control of single-isocenter multi-target (SIMT) stereotactic radiosurgery (SRS) treatment planning. Reliable dose estimation of normal brain tissue is one of the great indicators to evaluate plan quality and is used as a reference in clinics to improve potentially SIMT SRS treatment planning quality consistency. This study aimed to develop a spherical coordinate-defined deep learning model to predict the dose to a normal brain for SIMT SRS treatment planning.

METHODS

By encapsulating the human brain within a sphere, 3D volumetric data of planning target volume (PTVs) can be projected onto this geometry as a 2D spherical representation (in azimuthal and polar angles). A novel deep learning model spherical convolutional neural network (SCNN) was developed based on spherical convolution to predict brain dosimetric evaluators from spherical representation. Utilizing 106 SIMT cases, the model was trained to predict brain V50%, V60%, and V66.7%, corresponding to V10Gy and V12Gy, as key dosimetric indicators. The model prediction performance was evaluated using the coefficient of determination (R2), mean absolute error (MAE), and mean absolute percentage error (MAPE).

RESULTS

The SCNN accurately predicted normal brain dosimetric values from the modeled spherical PTV representation, with R2 scores of 0.92 ± 0.05/0.94 ± 0.10/0.93 ± 0.09 for V50%/V60%/V66.7%, respectively. MAEs values were 1.94 ± 1.61 cc/1.23 ± 0.98 cc/1.13 ± 0.99 cc, and MAPEs were 19.79 ± 20.36%/20.79 ± 21.07%/21.15 ± 22.24%, respectively.

CONCLUSIONS

The deep learning model provides treatment planners with accurate prediction of dose to normal brain, enabling improved consistency in treatment planning quality. This method can be extended to other brain-related analyses as an efficient data dimension reduction method.

A hybrid [18F]fluoropivalate PET-multiparametric MRI to detect and characterise brain tumour metastases based on a permissive environment for monocarboxylate transport

The incidence of Intracranial Metastatic Disease (IMD) continues to increase in part due to improvements in systemic therapy resulting in durable control of extra-cranial disease (ECD). Contrast-enhanced Magnetic Resonance Imaging (CE-MRI) is the preferred method for imaging IMD, but has limitations particularly in follow-up surveillance scans to optimise patient care. We investigate a new diagnostic approach of hybrid ([18]F]fluoropivalate (FPIA) Positron Emission Tomography-multiparametric MRI (PET-mpMRI), in 12 treatment-naïve and 10 stereotactic radiosurgery (SRS)-treated patients (± combination therapy within 4-8 weeks). High FPIA uptake was seen in all IMD compared to contralateral white matter, regardless of ECD tumour-of-origin (p = 0.0001) and FPIA-PET volumes extended beyond CE-MRI volumes in treatment-naïve but not SRS-treated tumours. Patients with maximum PET Standardised Uptake Value, (SUVmax) ≥ 2.0 showed particularly short overall-survival (median 4 v 15 months, p = 0.0136), while CE-MRI was uninformative regarding outcome; a PET-mpMRI grade-measure also provided non-invasive prediction of overall-survival, warranting larger studies of PET-mpMRI. Independent metabolomics analyses were consistent with shared adaptation of IMD to utilise or accumulate monocarboxylates and acylcarnitines, respectively, providing a common phenotypic basis to FPIA-PET. Reprogrammed monocarboxylate metabolism-related FPIA-PET provides new insights into annotating IMD, to be expounded in future opportunities for therapy decisions for the growing number of cancer patients with IMD [Trial registration reference: Clinicaltrials.gov NCT04807582; 3rd November 2021, retrospectively registered].

Stereotactic Radiosurgery Dose Reduction for Melanoma Brain Metastases Patients on Immunotherapy or Target Therapy: A Single-Center Experience

BACKGROUND AND OBJECTIVES

Better local control but higher rates of adverse radiation events (ARE) have been reported when combining American Society for Radiation Oncology (ASTRO)-guideline-suggested dose (SD) stereotactic radiosurgery (SRS) with immunotherapy or targeted therapy for melanoma brain metastases. The objective of this study is to explore the efficacy and safety of lower prescription doses compared with ASTRO guidelines for single-fraction SRS for patients with melanoma metastases who are concurrently receiving immunotherapy or targeted therapy.

METHODS

We conducted a retrospective, single-center study on 194 patients who underwent SRS between 2009 and 2022. After propensity score matching, 71 patients with 292 metastases were included in the ASTRO-SD (20-24 Gy for <2 cm, 18 Gy for ≥2 to <3 cm) group and 33 patients with 292 metastases in the reduced dose (RD, <20 Gy for <2 cm, <18 Gy for ≥2 to <3 cm) group.

RESULTS

The median diameter (5.4 vs 5.2 mm, P = .6), prescription volume (0.2 vs 0.2 cm 3 , P = .2), and radiographic follow-up (11 vs 12 months, P = .2) were similar in the 2 groups. The cumulative incidence of progressing metastases was significantly higher in the SD compared with the RD group ( P = .018). Higher prescription volumes and ASTRO-suggested radiation doses were associated with local progression in multivariable analysis. Radiographic AREs were significantly more common in the SD compared with the RD group (8.6% vs 3.1%, P = .005). BRAF and other tyrosine kinase inhibitors' concurrent use, higher prescription volumes, and ASTRO-suggested radiation doses were associated with an increased risk of radiographic ARE.

CONCLUSION

This study provides evidence that RD SRS could offer reduced toxicity rates, while maintaining high local control as compared with the current guideline-SDs for the treatment of melanoma brain metastases.

T-DM1 with concurrent radiotherapy in HER2-positive breast cancer: preclinical evaluation and mechanisms, prediction, and exploration of adverse effects

Human epidermal growth factor receptor 2 (HER-2) serves as a pivotal target for breast cancer treatment and a vital prognostic marker. Anti-HER-2 therapies, which are integral to the management of HER-2-positive breast cancer, including monoclonal antibodies (e.g., trastuzumab and pertuzumab), tyrosine kinase inhibitors (e.g., lapatinib and pyrotinib), and antibody-drug conjugates (ADCs) such as trastuzumab emtansine (T-DM1). ADCs consist of a monoclonal antibody, a linker, and a cytotoxic payload, engineered to deliver chemotherapy selectively to tumor cells, thereby reducing the systemic toxicity associated with traditional chemotherapy. T-DM1, a HER-2-targeting ADC, combines the humanized anti-HER-2 IgG1 trastuzumab with DM1, a cytotoxic agent that inhibits microtubule formation. T-DM1 has significantly enhanced the prognosis of HER-2-positive breast cancer patients who fail to achieve a pathological complete response or develop distant metastases after neoadjuvant trastuzumab and pertuzumab therapy. While the combination therapy of T-DM1 with radiotherapy demonstrates an acceptable safety profile overall, clinicians should remain vigilant regarding potential severe treatment-related toxicities that have been observed in specific clinical scenarios. Nevertheless, limited research exists regarding the adverse effects and mechanisms of T-DM1 in combination with radiotherapy. This review investigates preclinical studies on the interactions between T-DM1 and radiotherapy, investigates associated adverse effects and their underlying mechanisms, identifies predictive factors and prognostic implications, and explores potential therapeutic strategies involving the concurrent T-DM1 with radiotherapy.

Hybrid Deep Learning for Survival Prediction in Brain Metastases Using Multimodal MRI and Clinical Data

Background: Survival prediction in patients with brain metastases remains a major clinical challenge, where timely and individualized prognostic estimates are critical for guiding treatment strategies and patient counseling. Methods: We propose a novel hybrid deep learning framework that integrates volumetric MRI-derived imaging biomarkers with structured clinical and demographic data to predict overall survival time. Our dataset includes 148 patients from three institutions, featuring expert-annotated segmentations of enhancing tumors, necrosis, and peritumoral edema. Two convolutional neural network backbones-ResNet-50 and EfficientNet-B0-were fused with fully connected layers processing tabular data. Models were trained using mean squared error loss and evaluated through stratified cross-validation and an independent held-out test set. Results: The hybrid model based on EfficientNet-B0 achieved state-of-the-art performance, attaining an R2 score of 0.970 and a mean absolute error of 3.05 days on the test set. Permutation feature importance highlighted edema-to-tumor ratio and enhancing tumor volume as the most informative predictors. Grad-CAM visualizations confirmed the model's attention to anatomically and clinically relevant regions. Performance consistency across validation folds confirmed the framework's robustness and generalizability. Conclusions: This study demonstrates that multimodal deep learning can deliver accurate, explainable, and clinically actionable survival predictions in brain metastases. The proposed framework offers a promising foundation for integration into real-world oncology workflows to support personalized prognosis and informed therapeutic decision-making.

ENDOCAN-TUTHYREF guidelines. Locoregional therapies for locally advanced and/or metastatic thyroid cancer

This article presents consensus recommendations by a multidisciplinary panel of endocrinologists, medical oncologists, pathologists, radiation oncologists, surgeons and nuclear medicine physicians. The recommendations specifically address iodine-refractory well-differentiated thyroid carcinoma and locally advanced and/or metastatic medullary thyroid carcinoma. Treatment algorithms based on risk-benefit assessments of various multimodal therapeutic approaches are proposed for each clinical scenario. Given the limited data available on the management of these rare but aggressive forms of thyroid cancer, these consensus recommendations provide essential guidance for multidisciplinary teams to ensure optimal care for patients with these complex thyroid carcinomas.

The 2024 revised clinical guidelines on the management of thyroid tumors by the Japan Association of Endocrine Surgery

The Japan Association of Endocrine Surgery published the first edition of the "Clinical guidelines on the management of thyroid tumors" in 2010 and the revised edition in 2018. The guideline presented herein is the English translation of the revised third edition, issued in 2024. The aim is to enhance health outcomes for patients suffering from thyroid tumors by facilitating evidence-based shared decision-making between healthcare providers and patients, as well as standardizing the management of thyroid tumors. The focus is on adult patients with thyroid tumors, addressing clinically significant issues categorized into areas such as an overview of the diagnosis and treatment of thyroid nodules, treatment strategies by histological type, radioactive iodine therapy, treatment of advanced differentiated carcinoma, pharmacotherapy, and complications and safety management associated with thyroid surgery. Thirty-two clinical questions were established in these areas. Following a comprehensive search of the literature and systematic review to evaluate the overall evidence, we aimed to present optimal recommendations by considering the balance of benefits and harms from the patient's perspective. We integrated evidence and clinical experience to determine the "Certainty of evidence" and "Strength of recommendations". Based on these, we illustrated overall flows of care as "Clinical algorithms". Necessary background knowledge of diseases and established clinical procedures for understanding the recommendations are presented in "Notes", while information that may be clinically useful but for which evidence remains insufficient is included in "Columns", based on the current state of evidence. Finally, future challenges for the next revision are presented as "Future research questions".

Local recurrence and radionecrosis after single-isocenter multiple targets stereotactic radiotherapy for brain metastases

Stereotactic radiotherapy (SRT) is frequently used to treat brain metastases (BMs). The single-isocenter for multiple targets (SIMT) technique allows for faster treatment of large numbers of BMs, but may adversely affect planning target volume (PTV) coverage due to possible increased positioning uncertainties with an increased isocenter to tumor distance (ITD). This study aims to investigate the association of ITD with local recurrence (LR) and radionecrosis (RN). Patients treated with SRT using a single isocenter for multiple BMs were retrospectively analyzed. Previous cranial radiotherapy and inability to undergo MR imaging were exclusion criteria. Patients were irradiated using a Versa HD LINAC with 6 MV flattening filter-free (FFF) energy and a 6D robotic couch. A non-coplanar volumetric modulated arc technique was used and plans were delivered using 6MV FFF energy. Associations between potential risk factors and LR/RN were investigated with Cox regression analyses. Seventy-five patients with a total of 357 BMs were included. Median survival after SRT was nine months. LR occurred in 7 (9%) patients and 10 (13%) had RN. After 18 months, LR-free survival was 89% and RN-free survival was 85%, respectively. ITD was not significantly associated with LR and RN. GTV was significantly associated with both LR (HR 1.10, 95% CI 1.02-1.17, P 0.0079) and RN (HR 1.09, 95% CI 1.01-1.17, P 0.020). LINAC-based SIMT SRT is a safe and effective treatment modality for patients with multiple BMs. We found no increased risk of LR or RN for BMs located further away from the isocenter.

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.

Current Treatment Paradigms for Advanced Melanoma with Brain Metastases

The therapeutic management of melanoma brain metastases has undergone a profound revolution during recent decades. Optimal integration of systemic therapies with local treatments seems to represent the strategy to pursue in order to maximize clinical outcomes, stressing the need for real multidisciplinary care in this setting of patients. However, the current approach in the clinics does not necessarily reflect what the current guidelines state, and several pending issues are present, from the ideal therapeutic sequence between stereotactic radiosurgery (SRS) and drug administration to the current role of surgery and whole brain radiotherapy (WBRT), all of which need to be addressed. This narrative review aims to provide practical help for navigating the current controversies, with an eye towards possible future advancements in the field, which could help to obtain a comprehensive molecular characterization of the tumor and a more personalized patient-centered therapeutic approach.

Efficacy analysis of brain radiotherapy in EGFR mutation non-small cell lung cancer with brain metastasis: a retrospective study

OBJECTIVES

Patients with epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) are at a heightened risk of developing brain metastases (BM). EGFR-tyrosine kinase inhibitors (TKI) are standard treatment for EGFR-mutated NSCLC. However, the necessity and optimal approach of brain radiotherapy for NSCLC patients with EGFR mutation remain inconclusive. We aimed to answer these questions by retrospectively analyzing the efficacy of radiotherapy in patients with BM from NSCLC with EGFR mutations.

METHODS

Patients with EGFR- mutant NSCLC and BMs who were diagnosed between January 1, 2018 and December 31, 2022 were included. According to treatment methods those patients were divided into whole brain radiotherapy (WBRT) plus EGFR-TKI (WBRT group), stereotactic radiotherapy (SRT) plus EGFR-TKI (SRT group) and EGFR-TKI alone (TKI-only group). Propensity-score-matching (PSM) was performed to minimize the effect of possible confounding factors and to balance treatment groups.

RESULTS

A total of 142 patients were included in this study. The median follow-up time was 22 months (range, 3.0-43.0 months). In the PSM cohort, the median intracranial progression free survival (iPFS) was 14, 30, 12 months and the median overall survival (OS) was 27 months, not reach and 33 months in WBRT group, SRT group and TKI-only group, respectively. Compared with the other two groups, SRT group significantly improved iPFS and OS (p < 0.05). And the local progression rate of intracranial lesions in SRT group was significantly reduced (p < 0.05).

CONCLUSION

This study showed that SRT combined with TKI may improve iPFS and prolong survival in patients with EGFR mutations in BMs from NSCLC.

Efficacy and safety of online adaptive magnetic resonance-guided fractionated stereotactic radiotherapy for brain metastases in non-small cell lung cancer (GASTO-1075): a single-arm, phase 2 trial

Background

Brain metastases (BMs) in non-small cell lung cancer (NSCLC) are associated with poor prognosis and quality of life (QoL). This study aimed to evaluate the efficacy and safety of online adaptive MR-guided fractionated stereotactic radiotherapy (FSRT) using a 1.5 T MR-Linac in this subgroup of patients.

Methods

This single-arm phase 2 trial was conducted at Sun Yat-sen University Cancer Centre. Patients aged 18-75 years with NSCLC, 1-10 BMs, and an ECOG status of 0-1 were included. Key exclusion criteria included inability to undergo contrast-enhanced MRI and contraindications to bevacizumab. Patients received 30 Gy adaptive FSRT in 5 daily fractions under real-time MR guidance, with bevacizumab before (day 1) and after (day 21) FSRT. The primary endpoint was 1-year intracranial progression-free survival (IPFS); secondary endpoints included objective response rate (ORR), 1-year progression-free survival (PFS), 1-year overall survival (OS), treatment-related toxicities, and QoL. All enrolled patients were included in primary and safety analyses. This trial is registered with Clinicaltrials.gov, NCT04946019.

Findings

Between June 10th, 2021 and June 29th, 2023, 70 patients were assessed for eligibility and 55 patients were enrolled (median follow-up: 22.3 months). The median age was 58 years (IQR: 51-65), with 33% (18/55) female patients, and 82% (45/55) presenting with adenocarcinoma. The 1-year IPFS rate was 78.7% (95% CI, 68.2%-90.7%), with a median IPFS of 21.9 months (95% CI, 13.8-30.1 months). The 1-year PFS rate was 63.5% (95% CI: 51.8%-78.2%), and OS was 82.4% (95% CI: 72.6%-93.6%). The ORR reached 78% (95% CI: 65.0%-88.2%). Treatment-related toxicity was minimal, with only one case (2%) of grade 1 radiation necrosis. QoL improved steadily, with the Global Health Status score increasing from 65.67 ± 16.97 to 79.33 ± 8.79 at 6 months post FSRT (p < 0.0001).

Interpretation

Online adaptive FSRT using a 1.5 T MR-Linac has demonstrated effectiveness and good tolerability for BMs in patients with NSCLC. However, the relatively small sample size and short follow-up may affect result generalizability. Further randomised studies are warranted to confirm these findings and establish optimal treatment protocols.

Funding

The National Natural Science Foundation of China (Grant Number 82073328).

Intracerebral and pituitary metastatic eccrine carcinoma: prolonged survival using stereotactic radiosurgery

PURPOSE

Eccrine gland carcinoma (EC) is a rare skin neoplasm that uncommonly spreads to the brain or pituitary gland. We describe the role of multiple stereotactic radiosurgery (SRS) procedures to manage recurrent brain metastases of this rare disease.

MATERIALS AND METHODS

Retrospective chart review was completed to obtain details for this report. The study was performed under IRB study on medical record only and was exempt from patient's consent.

RESULTS AND CONCLUSIONS

A 59-year-old female underwent surgical excision of a right parietal scalp EC. Over the next 13 years, the patient underwent initial fractionated whole brain radiation therapy after she developed multiple brain metastases followed by systemic chemotherapy for extracranial disease. Because of repeated development of new brain disease, three SRS procedures were performed to treat a total of 50 brain metastases and a pituitary metastasis (PM). The patient expired from progressive systemic cancer spread 13 years after her initial surgical excision. Due to the rarity of metastatic EC to the brain, no standard treatment paradigm has emerged. Using multimodality options that included local excision of the original skin tumor, followed by radiation, systemic chemotherapy, and three SRS procedures, long-term survival was possible in this unusual case.

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.

Immunotherapy promoting spontaneous regression of non-irradiated brain Metastases following gamma knife treatment: an intracranial abscopal effect?

Radiotherapy has been shown to potentially induce systemic anti-tumor immunity, a phenomenon that may be further enhanced by immune checkpoint inhibitor (ICI) therapy. However, whether this phenomenon occurs following Gamma Knife radiosurgery (GKRS) for brain metastases (BMs) and its potential clinical implications remain poorly understood. We retrospectively analyzed 36 non-small-cell lung cancer (NSCLC) patients with multiple BMs treated with multi-session GKRS. Spontaneous tumor regression (STR) was defined as ≥ 30% volume reduction in non-irradiated tumors. Competing risks analysis and Cox regression were used to evaluate local progression, distant brain failure (DBF), and survival outcomes. In this study, 44% (16/36) of patients received ICI therapy. STR was observed in 38.9% (14/36) of the cohort. Comparative analysis revealed that patients received ICI therapy did not exhibited an improved overall survival (OS) (p = 0.46), but demonstrated a trend toward a higher incidence of STR compared to those without ICI therapy (56.3% vs. 25.0%, p = 0.056). Multivariable regression analysis identified the absence of STR as an independent risk factor for mortality (Hazard Ratio [HR], 7.69; 95% CI: 1.61-33.33; p = 0.009) and local tumor progression (HR, 5.05; 95% CI: 1.71-14.93; p = 0.003). A systemic anti-tumor immunity could be induced by GKRS and cause STR of non-irradiated tumors. Patients exhibiting this phenomenon demonstrate significantly improved survival rates and local tumor control compared to those without this response. These findings underscore the potential immunomodulatory role of GKRS and its clinical implications in the management of BMs.

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.

Optimizing normal tissue objectives (NTO) in eclipse treatment planning system (TPS) for stereotactic treatment of multiple brain metastases using non-coplanar RapidArc and comparison with HyperArc techniques

PURPOSE

To optimize NTO parameters in non-coplanar RapidArc (RA) stereotactic radiosurgery (SRS) for multiple brain metastases and compare them with HyperArc (HA) plans.

MATERIALS AND METHODS

Thirty patients with multiple brain metastases, receiving 21 Gy prescriptions, were retrospectively enrolled, with lesions ranging from two to eight and volumes between 0.27 and 10.56 cm3. Non-coplanar RapidArc plans utilized manual NTO (RA-mNTO) with varying dose fall-off values (0.1 mm-1, 0.5 mm-1, 1.0 mm-1, 2.0 mm-1, 3.0 mm-1) and end doses (50%, 25% & 10%). Additionally, two HyperArc plans were generated: HA-ALDO used Automatic Lower Dose Objectives with SRS NTO, while HA-mNTO used the same beam geometry with manual NTO parameters optimized from RA-mNTO plans. TrueBeam with High-Definition Multi-leaf Collimators (HDMLC), 6 MV Flattening Filter Free (FFF) Beam at a maximum dose rate of 1400 MU/min, and Eclipse version 16.1 TPS were used. Plans were assessed for Paddick Conformity Index (CI), Gradient Index (GI), Homogeneity Index (HI), normal brain doses (V18Gy, V15Gy, and V12Gy), Monitor Units (MUs), and delivery accuracy using aS1200 Digital Megavolt Imager (DMI) with 2%/2 mm gamma criteria. Statistical analysis utilized integrated scoring and the Wilcoxon signed-rank test.

RESULTS

RA-mNTO plans with 0.5 mm⁻1 dose fall-off and 10% end-dose showed superior dosimetric outcomes: CI (0.85 ± 0.08), GI (3.63 ± 0.87), and HI (0.36 ± 0.06) compared to HA-ALDO (CI 0.84 ± 0.09, GI: 3.97 ± 0.85, HI: 0.39 ± 0.07) and HA-mNTO (CI 0.83 ± 0.08, GI: 3.60 ± 0.93, HI: 0.40 ± 0.06). MUs were comparable: RA-mNTO (9679 ± 1882), HA-ALDO (9509 ± 1315), and higher for HA-mNTO (10,457 ± 1980). RA-mNTO plans exhibited significantly lower normal brain doses (V18Gy: 1.78 ± 1.23, V15Gy: 3.54 ± 2.37, V12Gy: 6.21 ± 4.09) compared to HA-ALDO (V18Gy: 2.02 ± 1.34, V15Gy: 4.09 ± 2.66, V12Gy: 7.15 ± 4.56) and HA-mNTO (V18Gy: 1.85 ± 1.20, V15Gy: 3.68 ± 2.33, V12Gy: 6.36 ± 3.97). All techniques achieved > 98% gamma pass rate.

CONCLUSION

Non-coplanar RA plans with optimized mNTO settings outperformed HyperArc plans in all studied dosimetric parameters for SRS treatment of multiple brain metastases.

The METACER national cohort study of brain metastases in gastrointestinal cancers prospectively establishes prognostic factors

PURPOSE

Availability data are scarce and primarily retrospective in patients with brain metastasis (BM) from gastrointestinal (GI) cancers. The objective of this cohort was to determine prognostic factors for survival outcomes in patients with BM from GI cancers.

METHODS

METACER is a national multicentric prospective cohort study which included patients with BM diagnosis during a histologically proven digestive cancer follow-up between 2010 and 2014. The primary endpoint was overall survival (OS). The secondary endpoints were Progression-Free survival (PFS), prognostic factors, and BM-free survival as time from disease diagnosis to BM diagnosis.

RESULTS

METACER included 130 patients, with colorectal cancer (CRC) (N = 105) and eso-gastric (N = 25) cancer (EGC). The median OS was 6.6 months: 7.1 months (95%CI: 4.7-9.7) in CRC patients and 5.2 months, (95%CI: 1.9-7.6) in EG patients (p = 0.827). In multivariate analysis, cerebral BM location (versus cerebellar), BM surgery, performance status (0-1 versus 2), and a unique BM were significantly associated with prolonged OS. BM-free survival were 30.8 months (95%CI:25.2-36.9) in CRC patients and 7.8 months (95%CI:3.8-13.6) in EGC patients (p < 0.001). In synchronous metastatic disease, BM-free survival were 18.6 months (95%CI:13.1-25.2) in CRC patients and 3.7 months (95%CI:0.03-7.8) in EGC patients (p < 0.001).

CONCLUSION

BM in GI cancers are of poor prognosis. BM surgery should be considered in case of unique brain lesion. In metastatic settings, EGC patients have shorter BM-free survival than CRC patients.

Dosimetric impact of arc simulation angular resolution in single-isocentre multi-target stereotactic radiosurgery

This study evaluates the dosimetric impact of arc simulation angular resolution in VMAT-based Single Isocentre Multiple Target (SIMT) SRS, focusing on their dependence on target size, isocentre distance, number of arcs, and arc type. A phantom study analysed angular resolution (0.5°, 1°, 2°) effects on dosimetric accuracy for PTVs of 0.5 cm, 1 cm, and 2 cm at distances of 2.5 cm, 5 cm, and 7.5 cm from the isocentre using conformal arc and VMAT plans. Clinical validation involved 32 patients with 2-8 brain metastases, comparing plans recalculated at 1° and 2° resolutions. Dosimetric parameters included: Dnear-Min, Dnear-Max, Dmean, Dmedian, TVPIV, CIPaddick, GI, and Brain-GTV 12 Gy. For the 0.5 cm diameter target located at 7.5 cm distance from isocentre, phantom results showed TVPIV, Dmean, and GI deviations of 7.91%, 1.8%, and 0.85 for single-conformal arcs, which decreased to 4.84%, 1.3%, and 0.77 with 4-conformal arcs, and 3.4%, 0.96%, and 0.5 for 4-arc VMAT. Deviations varied based on target size, isocentre distance, number of arcs, and arc type. Clinical results mirrored the phantom study, with maximum TVPIV and GI deviations of 2.76% and 0.65 for the smallest target (0.6 cm) located at 7.5 cm distance for four-arc VMAT. Other dosimetric parameters showed minimal variations (< 1%). Correlation analysis revealed strong associations between dosimetric differences, target size, and distance (r = 0.6-0.78 for small targets). MANOVA identified TVPIV as the only significant parameter (p = 0.01). A 1° angular resolution significantly improves dosimetric accuracy for small, distally located targets in SIMT SRS.

[Recommendations for the management of oligometatic NSCLC]

The concept of oligometastatic disease in lung cancer has been the subject of much publication and speculation. Indeed, beyond its definition, which is still a matter of debate, it is a rather broad concept considering synchronous oligometastatic disease but also oligoprogression and oligopersistence concepts. These questions are increasingly common considering the improvement of systemic treatments in recent years. Although no prospective randomized trial has been conducted to date, it would seem appropriate to offer patients local ablative treatment of oligoprogression, especially if symptomatic or in cases of oncogenic addiction. On the other hand, the most recent data do not defend the closure treatment approach for patients who benefit from immunotherapy. All in all, it is important to remember that systemic therapy remains the cornerstone of treatment for metastatic lung cancer, and that further robust randomized studies will be needed to determine the place of local therapy.

Brain metastases from lung cancer: recent advances and novel therapeutic opportunities

Metastatic intracranial progression drastically impacts prognosis, therapeutic considerations and quality of life. The increasing incidence of lung cancer patients developing brain metastases (BM) parallels the incorporation of more effective systemic agents and improved surveillance. Our evolving knowledge of BM pathophysiology, along with advancements in surgical, radiotherapy and systemic therapy options, is rapidly changing prognostication and treatment paradigms. Optimal management of BM in the modern era is patient-specific, dependent on performance status, comorbidities, intracranial and extracranial disease burden, leptomeningeal disease, and the presence of targetable mutations. The purpose of this review is to provide a detailed overview of the detection, prognostication, and multidisciplinary, management of BM arising from non-small cell lung cancer and small cell lung cancer. We discuss contemporary evidence and active clinical trials supporting a wide array of treatment options, including surgery, radiosurgery, memory-avoidance whole brain radiation, craniospinal irradiation, chemotherapy, targeted agents and immunotherapy. Multidisciplinary paradigms will continue to evolve as currently accruing randomized trials evaluating these promising treatments options mature.

Stereotactic radiosurgery for 1-10 brain metastases to avoid whole-brain radiotherapy: Results of the CYBER-SPACE randomized phase 2 trial

BACKGROUND

Stereotactic radiosurgery (SRS) is an emerging alternative to whole-brain radiotherapy (WBRT) for treating multiple brain metastases (BM), reducing toxicity, and improving tumor control. The CYBER-SPACE trial compared SRS based on either SPACE or MPRAGE MRI sequence for avoiding or delaying WBRT in patients with 1-10 BM.

METHODS

Patients with 1-10 untreated BM were randomized 1:1 to receive SRS of all lesions based on either SPACE or MPRAGE MRI sequences. If subsequently new BM occurred, SRS was repeated. WBRT was indicated upon occurrence of >10 new BM, leptomeningeal disease, or exhausted SRS-radiotolerance. The primary outcome was freedom from WBRT indication (WBRTi). Secondary outcomes included overall survival (OS), safety, and quality of life.

RESULTS

A total of 202 patients were randomized; SPACE n = 99, MPRAGE n = 103. Twelve-month WBRTi-free survival was 77.1% (95% CI: 69.5%-83.1%) overall, 78.5% (95% CI: 66.7%-86.5%) for SPACE, and 76.0% (95% CI: 65.2%-83.9%) for MPRAGE (hazard ratio [HR] = 0.84, 95% CI: 0.43-1.63, P = .590). Patients with 5-10 BM had shorter WBRTi-free survival (HR = 3.13, 95% CI: 1.53-6.40, P = .002). Median OS was 13.1 months overall, 10.5 months for SPACE, and 15.2 months for MPRAGE (HR = 1.10, 95% CI: 0.78-1.56, P = .585). Neurologic death rate was 10.1%. Predictors for longer OS included Karnofsky Performance Status >80% (HR = 0.51, 95% CI: 0.33-0.77, P = .002) and concurrent immunotherapy (HR = 0.34, 95% CI: 0.23-0.52, P < .001).

CONCLUSIONS

The more sensitive SPACE sequence did not improve outcomes over MPRAGE. SRS with thorough monitoring and immediate re-treatment for new lesions decreases the need for WBRT and achieves low neurologic death rates. SRS should be considered a favorable alternative to WBRT for patients with 1-10 BM.

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.

Impact of the Novel MRI Contrast Agent Gadopiclenol on Radiotherapy Decision Making in Patients With Brain Metastases

PURPOSE

The aim of this study was to assess the effect of gadopiclenol versus gadobenate dimeglumine contrast-enhanced magnetic resonance imaging (MRI) on decision-making between whole-brain radiotherapy (WBRT) and stereotactic radiosurgery (SRS) for treatment of brain metastases (BMs).

METHODS

Patients with BMs underwent 2 separate MRI examinations in a double-blind crossover phase IIb comparative study between the MRI contrast agents gadopiclenol and gadobenate dimeglumine, both administered at 0.1 mmol/kg. The imaging data of a single site using identical MRI scanners and protocols were included in this post hoc analysis. Patients with 1 or more BMs in any of both MRIs were subjected to target volume delineation for treatment planning. Two radiation oncologists contoured all visible lesions and decided upon SRS or WBRT, according to the number of metastases. For each patient, SRS or WBRT treatment plans were calculated for both MRIs, considering the gross target volume (GTV) as the contrast-enhancing aspects of the tumor. Mean GTVs and volume of healthy brain exposed to 12 Gy (V 12 ), as well as Dice similarity coefficient scores, were obtained. The Spearman rank (ρ) correlation was additionally calculated for assessing linear differences. Three different expert radiation oncologists blindly rated the contrast enhancement for contouring purposes.

RESULTS

Thirteen adult patients were included. Gadopiclenol depicted additional BM as compared with gadobenate dimeglumine in 7 patients (54%). Of a total of 63 identified metastatic lesions in both MRI sets, 3 subgroups could be defined: A, 48 (24 pairs) detected equal GTVs visible in both modalities; B, 13 GTVs only visible in the gadopiclenol set (mean ± SD, 0.16 ± 0.37 cm 3 ); and C, 2 GTVs only visible in the gadobenate dimeglumine set (mean ± SD, 0.01 ± 0.01). Treatment indication was changed for 2 (15%) patients, 1 from no treatment to SRS and for 1 from SRS to WBRT. The mean GTVs and brain V 12 were comparable between both agents ( P = 0.694, P = 0.974). The mean Dice similarity coefficient was 0.70 ± 0.14 (ρ = 0.82). According to the readers, target volume definition was improved in 63.9% of cases (23 of 36 evaluations) with gadopiclenol and 22.2% with gadobenate dimeglumine (8 of 36), whereas equivalence was obtained in 13.9% (5 of 36).

CONCLUSIONS

Gadopiclenol-enhanced MRI improved BM detection and characterization, with a direct impact on radiotherapy treatment decision between WBRT and SRS. Additionally, a more exact target delineation and planning could be performed with gadopiclenol. A prospective evaluation in a larger cohort of patients is required to confirm these findings.

Stereotactic Radiosurgery for Choriocarcinoma Brain Metastases: Illustrative Case Presentation and Systematic Review

BACKGROUND

Choriocarcinoma (CC) is a rare and aggressive form of germ cell tumor. There is limited evidence describing clinical outcomes in patients with primary CC and brain metastases (BM). Only a few single case reports have documented the use of stereotactic radiosurgery (SRS) for CC BM.

METHODS

We retrospectively assessed patients who were treated with SRS for pure CC BM from 1998 to 2024. Lesion follow-up sizes and local tumor control status were evaluated after SRS treatment using response evaluation criteria in solid tumors criteria. A comprehensive literature search was performed for CC BM in accordance with PRISMA guidelines.

RESULTS

In our series, 3 patients with 7 CC BM underwent SRS. Two were male with testicular CC and one was female with gestational CC. The median diameter of the lesions was 8 mm, with a median volume of 0.14 cm3 at treatment. Magnetic resonance imaging at 3 and 6 months showed reductions in median diameters to 6 mm and 4 mm, respectively. At the last follow-up visits, one lesion had local progression at 15 months after SRS and 1 lesion had sustained complete response. The systematic review yielded 249 articles. After screening, 18 reports were identified for CC BM. Among these reports, only 3 single case reports document outcomes of SRS for CC BM.

CONCLUSIONS

SRS is a feasible and viable approach for CC BM, particularly in cases where immediate surgical management is not necessary. This is the largest report to date evaluating the outcome of CC BM treated with SRS.

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.

Spatial accuracy of dose delivery significantly impacts the planning target volume margin in linear accelerator-based intracranial stereotactic radiosurgery

The impact of three-dimensional (3D) dose delivery accuracy of C-arm linacs on the planning target volume (PTV) margin was evaluated for non-coplanar intracranial stereotactic radiosurgery (SRS). A multi-institutional 3D starshot test using beams from seven directions was conducted at 22 clinics using Varian and Elekta linacs with X-ray CT-based polymer gel dosimeters. Variability in dose delivery accuracy was observed, with the distance between the imaging isocenter and each beam exceeding 1 mm at one institution for Varian and nine institutions for Elekta. The calculated PTV margins for Varian and Elekta linacs that could cover the gross tumor volume with 95% probability at 95% of the institutions were 2.3 and 3.5 mm, respectively, in the superior-inferior direction. However, with multifactorial system management (i.e., high-accuracy 3D dose delivery with rigorous linac quality assurance, strict patient immobilization, and high intra-fractional positioning accuracy), these margins could be reduced to 1.0 mm and 1.5 mm, respectively. The findings indicate significant millimeter-level variability in 3D dose delivery accuracy among linacs installed in clinical settings. Thus, maximizing a linac's 3D dose delivery accuracy is essential to achieve the required PTV margin in intracranial SRS.

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.

Comparison of single- and multi-isocenter planning with Dynamic WaveArc for multiple brain metastases

Dynamic WaveArc (DWA) is a technique used for continuous, non-coplanar volumetric-modulated arc therapy on the Vero4DRT platform. This study aimed to evaluate the application of single-isocenter DWA (SI-DWA) for treating multiple brain metastases by comparing dose distribution and irradiation time with multi-isocenter DWA (MI-DWA) through retrospective treatment planning. Treatment plans were developed for SI-DWA and MI-DWA in 14 cases with 3-5 brain metastases. Parameters assessed included target dose indices, such as conformity index (CI) of the planning target volume (PTV), volumes of normal brain excluding gross tumor volumes (GTVs) receiving a single dose equivalent of 14 Gy (V14), V30%, V20%, V10%, volumes of normal brain, including GTVs receiving a single dose equivalent of 12 Gy (V12), D2% for other organs at risk, and beam-on time. SI-DWA showed inferior CI, V14, and V12 values for lesions with PTV volumes <1 cc, whereas it performed equivalently to MI-DWA for lesions with PTV volumes ≥1 cc. SI-DWA resulted in higher volumes of normal brain receiving low doses compared to MI-DWA. SI-DWA exhibited significantly shorter beam-on times than MI-DWA. In conclusion, SI-DWA is an effective method for treating multiple brain metastases with PTV volumes ≥1 cc, offering an index of radiation-induced brain necrosis comparable with MI-DWA while allowing for shorter irradiation times.

Single and multitarget stereotactic radiosurgery (SRS) with single isocenter in the treatment of multiple brain metastases (BM): institutional experience

INTRODUCTION

SRS for the treatment of limited brain metastases (BM) is widely accepted, but there are still limitations in the management of numerous BM. Frameless single-isocenter multitarget SRS is a novel technique that allows for rapid treatment delivery to multiple BM. We report our preliminary clinical, dosimetric, and patient´s shifts outcomes with this technique.

MATERIALS AND METHODS

We have reviewed clinical and dosimetric outcomes of patients with intact BM treated with SRS using one isocenter either for single (1BM) or multiple (≥ 2BM) targets). Immobilization was based on an SRS stereotactic mask. Elements Multiple Brain Mets SRS (Brainlab AG, Munich, Germany) software was used for registration, image fusion, target contouring, and treatment planning. Exactrac Dynamic (Brainlab AG, Munich, Germany) and a 6 degree of freedom couch were used for monitoring, correcting the position and assessing and applying residual errors also when couch rotations. During dose delivery, the patient position was monitored and registered using surface tracking and stereoscopic X-rays.

RESULTS

From May 2022 to December 2023, we treated 60 patients with a total of 255 BM. The 67% of patients had at least 2 BM treated and the average of treated BM per patient per course was 3.6 (range 1-13). The average total treated BM per patient (sum of all courses) was 4.4. Lung cancer was the most frequent (63%) primary tumor. 77% of cases were patients with a brain relapse and the remaining 23% had BM at diagnosis. Ninety-two percent of BM were treated with single fraction. The most used fractionations were 20 Gy (27.8%) and 21 Gy (43.5%), respectively, and the median PTV target volume (if single fraction) was 0,2 cc (range 0.016-4.32 cc). The median cumulative target volume per isocenter and the sum of all SRS courses were 1.37 and 1.46 cc, respectively. The 100% of patients completed the SRS treatment with no incidences. With an average follow-up of 8.3 months (0.1-19 months), we have not identified any local relapse, although 27% developed an intracranial relapse that was again treated with SRS in the 44% of cases. We did not find any relation between overall survival and the presence of any driver mutation (p = 0.97), presence of BM at diagnosis vs. recurrences (p = 0.113), number of courses of SRS (p = 0.688), number of isocenters (p = 0.679), or number of treated BM (1 vs. 2-3 vs. ≥ 4; p = 0.7). Healthy normal tissue constraints were adequately accomplished with a median V12 (if single dose) and V20 (if 5 fractions) of 0.2 and 5 cc, respectively. No acute toxicity > G2 was reported. Regarding patient positioning, monitoring, and registration based on X-ray imaging and surface guidance, patient shifts distributions were centered at 0.0 mm with standard deviations below 0.25 mm, except for the longitudinal shift based on X-rays, which was 0.35 mm. This implies an adequate fixation system, patient setup, and image guidance protocols. The mean total delivery time per fraction, from the first beam-on to the last beam-off, was 9.6 ± 4.8 min, with a range of 4.6-30.9 min. On average, repositioning occurred 1.2 times per fraction based on X-ray guidance and 0.6 times per fraction based on surface guidance.

CONCLUSION

Based on our preliminary experience, we find single isocenter for single and multitarget SRS technique is feasible, well tolerated and allows excellent local control. Regarding patient positioning, monitoring, and registration based on X-ray imaging and surface guidance, patients' shifts and repositioning rate are low enough to show an adequate fixation system, patient setup, and image guidance policies at our institution. Patient shifts during treatment are effectively managed by X-ray and SGRT verification. Low shift tolerances ensure patient stability, resulting in acceptable treatment times and patient repositioning rates. This dedicated workflow for SRS at our institution demonstrates excellent clinical outcomes. A longer follow-up period is necessary to evaluate the impact on long-term clinical outcomes.

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.

Fractionated stereotactic radiotherapy of brainstem metastases - Clinical outcome and prognostic factors

Introduction

Brain metastases (BM) are the most common malignancy in the central nervous system (CNS) and observed in approximately 30% of cancer patients. Brainstem metastases (BSM) are challenging because of their location and the associated neurological risks. There are still no general therapeutic recommendations in this setting. Stereotactic radiosurgery (SRS) is one of few possible local therapy options but limited due to the tolerance dose of the brainstem. There is still no standard regarding the optimal dose und fractionation.

Methods

We retrospectively analyzed 65 patients with fractionated stereotactic radiotherapy (fSRT) for 69 BSM. FSRT was delivered at a dose of 30 Gy in six fractions prescribed to the 70 % isodose performed with Cyberknife. Overall survival (OS), local control (LC) and total intracranial brain control (TIBC) were analyzed via Kaplan-Meier method. Cox proportional hazards models were used to identify prognostic factors.

Results

Median follow-up was 27.3 months. One-year TIBC was 35.0 % and one-year LC was 84.1 %. Median OS was 8.9 months. In total, local progression occurred in 7.7 % and in 8.2 % symptomatic radiation-induced contrast enhancements (RICE) were diagnosed. In univariate analysis the Karnofsky performance scale index (KPI) (p = 0,001) was an independent prognostic factor for longer OS. Acute CTCAE grade 3 toxicities occurred in 18.4 %.

Conclusion

FSRT for BSM is as an effective and safe treatment approach with high LC rates and reasonable neurological toxicity despite the poor prognosis in this patient cohort is still very poor. Clinical and imaging follow-up is necessary to identify cerebral progression and adverse toxicity including RICE.

Exploring the Current Challenges and Pioneering Clinical Applications of Stereotactic Radiotherapy in Cancer Treatment

Stereotactic radiotherapy (SRT) has become integral to modern oncology, offering the ability to deliver ablative doses while minimizing damage to surrounding normal tissues. Recent advancements in imaging integration, treatment planning, and dose delivery have expanded their clinical applications across various tumor types. However, challenges such as toxicity in anatomically critical regions, optimal margin determination, and the lack of standardized protocols persist. This review explores key issues in contemporary practice and highlights emerging clinical evidence across lung, liver, prostate, brain, and oligometastatic diseases. Further refinement in patient selection and treatment strategies is essential to maximize therapeutic efficacy and ensure safe implementation in broader clinical settings.

Extended nnU-Net for Brain Metastasis Detection and Segmentation in Contrast-Enhanced Magnetic Resonance Imaging With a Large Multi-Institutional Data Set

PURPOSE

The purpose of this study was to investigate an extended self-adapting nnU-Net framework for detecting and segmenting brain metastases (BM) on magnetic resonance imaging (MRI).

METHODS AND MATERIALS

Six different nnU-Net systems with adaptive data sampling, adaptive Dice loss, or different patch/batch sizes were trained and tested for detecting and segmenting intraparenchymal BM with a size ≥2 mm on 3 Dimensional (3D) post-Gd T1-weighted MRI volumes using 2092 patients from 7 institutions (1712, 195, and 185 patients for training, validation, and testing, respectively). Gross tumor volumes of BM delineated by physicians for stereotactic radiosurgery were collected retrospectively and curated at each institute. Additional centralized data curation was carried out to create gross tumor volumes of uncontoured BM by 2 radiologists to improve the accuracy of ground truth. The training data set was augmented with synthetic BMs of 1025 MRI volumes using a 3D generative pipeline. BM detection was evaluated by lesion-level sensitivity and false-positive (FP) rate. BM segmentation was assessed by lesion-level Dice similarity coefficient, 95-percentile Hausdorff distance, and average Hausdorff distance (HD). The performances were assessed across different BM sizes. Additional testing was performed using a second data set of 206 patients.

RESULTS

Of the 6 nnU-Net systems, the nnU-Net with adaptive Dice loss achieved the best detection and segmentation performance on the first testing data set. At an FP rate of 0.65 ± 1.17, overall sensitivity was 0.904 for all sizes of BM, 0.966 for BM ≥0.1 cm3, and 0.824 for BM <0.1 cm3. Mean values of Dice similarity coefficient, 95-percentile Hausdorff distance, and average HD of all detected BMs were 0.758, 1.45, and 0.23 mm, respectively. Performances on the second testing data set achieved a sensitivity of 0.907 at an FP rate of 0.57 ± 0.85 for all BM sizes, and an average HD of 0.33 mm for all detected BM.

CONCLUSIONS

Our proposed extension of the self-configuring nnU-Net framework substantially improved small BM detection sensitivity while maintaining a controlled FP rate. Clinical utility of the extended nnU-Net model for assisting early BM detection and stereotactic radiosurgery planning will be investigated.

Targeting CNS Metastases in Non-Small Cell Lung Cancer With Evolving Approaches Using Molecular Markers: A Review

Importance

Central nervous system (CNS) metastases presenting as either brain parenchymal metastases or leptomeningeal metastases are diagnosed in up to 50% of patients with advanced non-small cell lung cancer during their disease course. While historically associated with a poor prognosis due to limited treatment options, the availability of an increasing number of targeted therapies with good CNS penetration has significantly improved clinical outcomes for these patients. This has occurred in parallel with a more nuanced understanding of prognostic factors.

Observations

Multiple clinical trials have reported that disease control can be observed with targeted therapies with adequate CNS penetration, particularly for patients with molecular alterations in EGFR, ALK, ROS1, and RET. For these tumors, systemic targeted therapy may be used first for the management of CNS metastases, prior to considering radiation therapy (RT). At the time of isolated progression in the CNS, RT may be considered for the progressing lesions with continuation of the same systemic therapy. For other molecular alterations as well as for patients treated with checkpoint inhibitors, data are not yet clear if systemic therapy is sufficient for untreated CNS metastases, and early RT may need to be integrated into the treatment planning. An increasing number of studies investigate the role that emerging techniques, such as the sequencing of tumor DNA from resected brain metastases tissue or cerebrospinal fluid or radiomics-based analysis of CNS imaging, can play in guiding treatment approaches.

Conclusions and Relevance

With multiple generations of targeted therapies now available, the treatment for CNS metastases should be tailored to the patients with consideration given to molecular testing results, CNS penetrance of systemic therapy, patient characteristics, and multidisciplinary review. More research is needed in understanding the clonal evolution of CNS metastases, and the development of novel therapeutics with CNS efficacy.

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.

The multidisciplinary management of HER2-positive breast cancer brain metastases: from new biological insights to future therapeutic options

The advent and success of new drugs for treating HER2-positive metastatic breast cancer has led to a constant improvement in disease and progression-free survival as well as overall survival. Despite these advantages, the overall survival and quality of life of patients with HER2-positive breast cancer brain metastases are significantly worse than the ones of patients with HER2-positive breast cancer metastases outside the brain. For this reason, prevention and treatment of brain metastasis remain a major clinical challenge and the keys to further improving the clinical and survival outcomes of HER2-positive breast cancer patients. This review discusses the etiopathogenesis of brain metastasis, the currently available treatments, and the future perspective on new treatment strategies and diagnostic tools.

Validation of the graded prognostic assessment and recursive partitioning analysis as prognostic tools using a modern cohort of patients with brain metastases

Background

Prognostic indices for patients with brain metastases (BM) are needed to individualize treatment and stratify clinical trials. Two frequently used tools to estimate survival in patients with BM are the recursive partitioning analysis (RPA) and the diagnosis-specific graded prognostic assessment (DS-GPA). Given recent advances in therapies and improved survival for patients with BM, this study aims to validate and analyze these 2 models in a modern cohort.

Methods

Patients diagnosed with BM were identified via our institution's Tumor Board meetings. Data were retrospectively collected from the date of diagnosis with BM. The concordance of the RPA and GPA was calculated using Harrell's C index. A Cox proportional hazards model with backwards elimination was used to generate a parsimonious model predictive of survival.

Results

Our study consisted of 206 patients diagnosed with BM between 2010 and 2019. The RPA had a prediction performance characterized by Harrell's C index of 0.588. The DS-GPA demonstrated a Harrell's C index of 0.630. A Cox proportional hazards model assessing the effect of age, presence of lung, or liver metastases, and Eastern Cooperative Oncology Group (ECOG) performance status score of 3/4 on survival yielded a Harrell's C index of 0.616. Revising the analysis with an uncategorized ECOG demonstrated a C index of 0.648.

Conclusions

We found that the performance of the RPA remains unchanged from previous validation studies a decade earlier. The DS-GPA outperformed the RPA in predicting overall survival in our modern cohort. Analyzing variables shared by the RPA and DS-GPA produced a model that performed analogously to the DS-GPA.

Stereotactic radiosurgery for pancreatic neuroendocrine tumor brain Metastases: Systematic review and Illustrative case presentation

BACKGROUND

Neuroendocrine tumor (NET) brain metastases (BM) are rare malignancies which frequently bear a poor prognosis and have the potential to secrete hormones. The optimal treatment approach for these metastases remains unclear, with significant heterogeneity occurring both across and within primary tumor types, and outcome data are limited. Pancreatic neuroendocrine tumor (pNET) BM may be particularly aggressive. While stereotactic radiosurgery (SRS) for other NET BM has previously been described, no report has specifically investigated SRS for management of pNET BM.

METHODS

A comprehensive literature search was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Search terms included ("neuroendocrine tumor" OR "neuroendocrine neoplasm" OR "neuroendocrine carcinoma" OR "NET") AND ("brain metastasis" OR "brain metastases" OR "intracranial metastases") AND ("stereotactic radiosurgery" OR "stereotactic body" OR "CyberKnife" OR "GammaKnife").

RESULTS

Our search strategy yielded 230 articles. After screening, a total of 16 articles with 256 patients were identified. Number of patients per study cohort ranged from 1 to 101 (mean = 16). Ten articles were single case reports. The most commonly investigated primary site was lung (5 studies), followed by skin (2 case reports), and uterine cervix (2 case reports). Median survival post-SRS ranged from 5 to 42 months. Median tumor volume ranged from 0.08 cm3 to 33.62 cm3. Local control rate was provided in 3 of 6 of the reviewed retrospective analyses. A pulmonary cohort of 101 patients reported a recurrence rate of 13.8 % at 12 months. A pulmonary case series similarly reported local progression in only 1 of 8 patients. The mixed primary cohort (33 patients) had a long-term local failure rate of 16.7 %. In addition, we describe a first reported individual case of pNET BM treated with SRS. Nearly 6-years after initial pNET diagnosis, multiple intracranial enhancing lesions were found, which were subsequently treated with SRS. Follow-up imaging demonstrated a statistically significant decrease in lesion diameter (p < 0.001), with none of the 18 BM progressing.

CONCLUSION

Given the recently increase in age-adjusted incidence of NET BM, determining an optimal treatment approach for these malignancies is of growing importance. Prognosis generally remains poor, with BM being a significant predictor of overall survival. Our review indicated large variability in outcomes both between and within primary tumor types, suggesting a need for further investigation of predictive molecular biomarkers. In addition, to the authors' knowledge, this represents the first reported case of pNET BM successfully treated with SRS.

Ablative Radiation Therapy to Restrain Everything Safely Treatable (ARREST): A Phase 1 Study of Stereotactic Ablative Radiation Therapy for Polymetastatic Disease

PURPOSE

This phase 1 study aimed to assess the safety and feasibility of SABR therapy delivery to all sites of polymetastatic disease (>10 metastases).

METHODS AND MATERIALS

A 3 + 3 study design was used with 5 dose levels from 6 Gy (6 Gy × 1) to 30 Gy (6 Gy weekly × 5). Dose-limiting toxicity (DLT) was defined as any grade 4 or 5 toxicity or more than 3 grade 3 toxicities within 6 weeks of treatment. The primary endpoint was the maximal tolerated dose, defined as the dose level where ≥2/6 of patients experienced DLT. Secondary endpoints included quality of life (Functional Assessment of Cancer Therapy - General and European Quality of Life 5 Dimension 5 Level) at 6 weeks posttreatment, progression-free survival, and overall survival.

RESULTS

Thirteen patients were accrued: 12 Gy (n = 3), 18 Gy (n = 3), 24 Gy (n = 4), and 30 Gy (n = 3), and 207 lesions were treated. Nine patients (69%) had acute toxicity: grade 1 (n = 6, 46%), grade 2 (n = 2, 15%; n = 1 pneumonitis and n = 1 fatigue), and grade 3 (n = 1, 7.7% neutropenia). There were no grade 4 or 5 toxicities. Mean ± SD quality of life (Functional Assessment of Cancer Therapy - General and European Quality of Life 5 Dimension 5 Level health state) was 80.4 ± 21.9 and 77.4 ± 20.9 at baseline versus 76.4 ± 21.8 and 68.0 ± 24.2 at 6-week follow-up, respectively (p = .009 and p = .055, respectively). With a median follow-up of 8.7 months posttreatment (IQR, 2.4-24 months), 8 of 13 patients had disease progression (62%). The median and 12-month progression-free survival were 3.6 months and 11.3%, respectively. The median and 12-month overall survival were 13.8 months and 62%, respectively.

CONCLUSIONS

In this phase 1 trial, SABR therapy for polymetastatic disease was technically feasible with acceptable acute toxicity at dose levels up to 30 Gy (6 Gy weekly × 5). DLT was not observed.

A phase II study of anlotinib plus whole brain radiation therapy for patients with NSCLC with multiple brain metastases

BACKGROUND

Whole brain radiotherapy (WBRT) is the mainstay of treatment for patients with non-small cell lung cancer (NSCLC) with multiple brain metastases (BMs); however, the BRAIN study showed that the efficacy of WBRT is unsatisfactory. This prospective phase II study aimed to evaluate the efficacy and safety of WBRT combined with anlotinib, a novel anti-angiogenic multi-target tyrosine kinase inhibitor (TKI), in patients with multiple BMs (>3) from advanced NSCLC.

METHODS

Patients with advanced NSCLC with multiple BMs who had received two or more lines of treatment were eligible for enrolment into this study. All patients were treated with anlotinib (8-12 mg, QD, on days 1-14 of a 21-day cycle) combined with WBRT (DT 30 Gy/12 F), followed by maintenance therapy with anlotinib until disease progression or treatment intolerance. The primary endpoint of this study was the intracranial progression-free survival (iPFS). The secondary endpoints were intracranial objective response rate (iORR), intracranial disease control rate (iDCR), overall survival (OS) and treatment safety.

RESULTS

Between May 2019 and January 2021, 28 patients were enrolled, all of whom were evaluable for efficacy and safety. The median age was 57.7 years, and 46.4% were male. Twenty-five patients had adenocarcinoma (89.3%), six had EGFR mutations (21.4%) and two had ALK mutations (7.1%). The median iPFS was 11.1 months (95% confidence interval (CI): 5.4-16.8 months) and the median OS was 13.4 months (95% CI: 5.2-21.6 months). The iORR was 71.4% (six complete responses + 14 partial responses). The most frequently observed adverse events (AEs) were hypertension (71.4%), fatigue (64.3%), anorexia (46.4%), and foot and hand skin reactions (25.0%). No patients developed ≥ grade 4 AEs. No intracranial haemorrhages occurred during treatment. Dose adjustment due to AEs occurred in 17.9% of patients.

CONCLUSIONS

Anlotinib combined with WBRT is effective and well-tolerated in patients with NSCLC with multiple BMs.

Assessing tumor volumetric reduction with consideration for setup errors based on mathematical tumor model and microdosimetric kinetic model in single-isocenter VMAT for brain metastases

The volumetric reduction rate (VRR) was evaluated with consideration for six degrees-of-freedom (6DoF) patient setup errors based on a mathematical tumor model in single-isocenter volumetric modulated arc therapy (SI-VMAT) for brain metastases. Simulated gross tumor volumes (GTV) of 1.0 cm and dose distribution were created (27 Gy/3 fractions). The distance between the GTV center and isocenter (d) was set at 0-10 cm. The GTV was translated within 0-1.0 mm (Trans) and rotated within 0-1.0° (Rot) in the three axis directions using affine transformation. The tumor growth volume was calculated using a multicomponent mathematical model (MCTM), and lethal effects of irradiation and repair from damage during irradiation were calculated by a microdosimetric kinetic model (MKM) for non-small cell lung cancer (NSCLC) A549 and NCI-H460 (H460) cells. The VRRs were calculated 5 days after the end of irradiation using the physical dose to the GTV for varying d and 6DoF setup errors. The tolerance value of VRR, the GTV volume reduction rate, was set at 5%, based on the pre-irradiation GTV volume. With the exception of the only one A549 condition where (Trans, Rot) = (1.0 mm, 1.0°) was repeated for 3 fractions, all conditions met all the tolerance VRR values for A549 and H460 cells with varying d from 0 to 10 cm. Evaluation based on the mathematical tumor model suggested that if the 6DoF setup errors at each irradiation could be kept within 1.0 mm and 1.0°, there would be little effect on tumor volume regardless of the distance from the isocenter in SI-VMAT.

Assessment of scintillation and Cherenkov imaging as beam shape verification method in CyberKnife® radiotherapy

PURPOSE

The goal of this study is to assess the utility of Cherenkov imaging (CI) and scintillation imaging (SI) as high-resolution techniques to measure CyberKnife® beam shape quantitatively at the irradiation surface in quality assurance (QA).

METHODS

The EMCCD camera captured scintillation and Cherenkov photons arising from 6 MV x-ray dose deposition produced by the CyberKnife® VSI System. Two imaging methods were done at source to surface distance of 800 cm with the same field size, ranging from 10 to 60 mm using fixed cones and iris collimators. The output sensitivity and constancy were measured using the SI and CI, and benchmarked against an ionization chamber. Line profiles of each beam measured by optical imaging were compared with film measurement. Position shifts were introduced to test the sensitivity of SI and CI to small beam position deviations. To assess reproducibility, the beam measurements were tested three times on 5 consecutive days.

RESULTS

Both systems exhibited comparable sensitivity to the ionization chamber in response to fluctuations in CyberKnife® output. The beam profiles in SI matched well with the measured film image, with accuracy in the range of ± 0.20 and ± 0.26 mm standard deviation for the circle and iris field, respectively. The corresponding accuracy measured by CI is in the range of ± 0.25 and ± 0.33 mm, respectively. These are all within the tolerance recommended by the guidelines of CyberKnife® QA. The accuracy measured by SI and CI for 1 mm beam position shift within 0.21 and 0.45 mm tolerance, respectively. Repeatability measurements of the beam have shown a standard deviation within 0.94 mm.

CONCLUSIONS

SI and CI techniques are tested to provide a valid way to measure CyberKnife® beam shape in this study. Meanwhile, the systematic comparison of SI and CI also provides evidence for the measurement methods selection appropriately.

Analysis of linear accelerator-based fractionated stereotactic radiotherapy in brain metastases: efficacy, safety, and dose tolerances

Objective

To assess the efficacy and safety of linear accelerator-based fractionated stereotactic radiotherapy (LINAC-FSRT) in patients with brain metastases (BM).

Methods

We retrospectively analyzed 214 patients treated with LINAC-FSRT, categorized based on biologically effective dose (BED10, α/β = 10) into two groups (≤55 Gy, >55 Gy). Stratified analyses were conducted based on targeted therapy to compare survival outcomes. To examine brain tissue dose-tolerance volume, patients were divided into two groups: the standard Hypofractionated Treatment Effects in the Clinic (HyTEC) protocol group and an adjusted HyTEC protocol group where dose-volume restrictions exclude the planning target volume (PTV).

Results

Results as of December 2023 showed median intracranial progression-free survival (iPFS) at 12.4 months, with median overall survival (OS) not reached and a one-year local control (LC) rate of 68.7%. Mild to moderate toxicity affected 17.3% of patients, while severe toxicity occurred in 2.8%. Multivariate Cox analysis indicated that uncontrolled extracranial disease significantly reduced iPFS (HR = 2.692, 95%CI:1.880-3.853, P < 0.001) and OS (HR = 3.063, 95%CI:1.987-4.722, P < 0.001). BED10 >55 Gy (HR = 0.656, 95%CI:0.431-0.998, P = 0.049) improved OS, showing statistical significance (P = 0.037) without affecting iPFS or CNS toxicity (P = 0.127, P = 0.091). Stratified analysis highlighted nearly significant OS improvements with high-dose FSRT and targeted therapy (P = 0.054), while concurrent therapy markedly enhanced iPFS (P = 0.027). No significant differences were observed in intracranial local failure (ILF-which represents progression in previously treated areas during follow-up), one-year LC rates, iPFS, or OS between dose-volume groups. Adjusting HyTEC volume restrictions did not significantly increase CNS adverse reactions (P = 0.889).

Conclusions

LINAC-FSRT is safe and effective in BM. BED10>55 Gy notably enhances OS post-LINAC-FSRT and may benefit LC. High BED10 FSRT with targeted therapy likely boosts synergy, and concurrent targeted therapy significantly improves iPFS. Diminishing dose volume constraints at different fractions based on the HyTEC guidelines is feasible.

The safety and efficacy of stereotactic radiosurgery in patients with gastrointestinal cancer brain metastasis: a systematic review and meta-analysis

Central nervous system Tumors, including metastasis, are a considerable source of morbidity and mortality. Currently, treatment options such as surgery, radiotherapy, and chemotherapy have been introduced to prevent the progression of the disease, but still, these patients do not have a good prognosis. Stereotactic radiosurgery (SRS) reduces the damage to the surroundings by focusing the radiation on the tumor tissue. In this paper, we aim to investigate the outcomes of SRS on patients with gastrointestinal-originated brain metastases. A systematic review and meta-analysis used the PRISMA guideline from inception until 27th March 2024, utilizing the relevant key terms. Records were screened and included based on pre-defined inclusion and exclusion criteria. Demanding data was extracted and analyzed using STATA v. 17. This meta-analysis of 29 studies examining SRS for brain metastases from gastrointestinal cancers revealed several significant findings. The pooled distant intracranial disease rate was 33% (95% CI: 0.21-0.45). Local tumor control rates were high, with an overall pooled rate of 88% (95% CI: 0.83-0.92). Survival outcomes showed a 6-month overall survival (OS) rate of 47% (95% CI: 0.42-0.52), decreasing to 32% at one year and 11% at two years. The 5-year OS rate was 2% (95% CI: 0.01-0.03). Subgroup analyses revealed variations in outcomes based on primary tumor site, with gastric cancer patients showing better short-term survival (73% at six months) compared to hepatic primaries (31% at six months). The 6-month progression-free survival (PFS) rate was 67% (95% CI: 0.12-1.22). Tumor control outcomes showed complete regression in 11% of cases, partial regression in 44%, stable disease in 30%, and progression in 20%. The overall mortality rate was 84% (95% CI: 0.75-0.93). This meta-analysis supports the efficacy of SRS in managing brain metastases from gastrointestinal cancers. SRS offers effective local control and may improve quality of life despite poor long-term outcomes. The high rates of distant intracranial progression underscore the need for comprehensive management strategies addressing both local and systemic disease. Future research should optimize patient selection, combine SRS with novel systemic therapies, and identify predictive biomarkers to improve outcomes in this challenging patient population.

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.