Frame-based radiosurgery of multiple metastases using single-isocenter volumetric modulated arc therapy technique

Radiosurgery for multiple brain metastases using volumetric modulated arc therapy: a single institutional series

Background

Patients with brain metastases (BM) live longer due to improved diagnosis and oncologic treatments. The association of volumetric modulated arc therapy (VMAT) and image-guided radiation therapy (IGRT) with brain radiosurgery (SRS) allows complex dose distributions and faster treatment delivery to multiple lesions.

Materials and methods

This study is a retrospective analysis of SRS for brain metastasis using VMAT. The primary endpoints were local disease-free survival (LDFS) and overall survival (OS). The secondary outcomes were intracranial disease-free survival (IDFS) and meningeal disease-free survival (MDFS).

Results

The average number of treated lesions was 5.79 (range: 2-20) per treatment in a total of 113 patients. The mean prescribed dose was 18 Gy (range: 12-24 Gy). The median LDFS was 46 months. The LDFS in 6, 12, and 24 months was for 86%, 79%, and 63%, respectively. Moreover, brain progression occurred in 50 patients. The median overall survival was 47 months. The OS in 75%, 69%, and 61% patients was 6, 12, and 24 months, respectively. IDFS was 6 and 24 months in 35% and 14% patients, respectively. The mean MDFS was 62 months; it was 6 and 24 months for 87% and 83% of patients. Acute severe toxicity was relatively rare. During follow-up, the rates of radionecrosis and neurocognitive impairment were low (10%).

Conclusion

The use of VMAT-SRS for multiple BM was feasible, effective, and associated with low treatment-related toxicity rates. Thus, treatment with VMAT is a safe technique to plan to achieve local control without toxicity.

Clinical outcomes of benign brain tumors treated with single fraction LINAC-based stereotactic radiosurgery: Experience of a single institute

Objectives

Accelerator-based stereotactic radiosurgery (SRS) is a noninvasive and effective treatment modality widely used for benign brain tumors. This study aims to report 20-year treatment outcomes in our institute.

Materials and Methods

From May 2001 to December 2020, 127 patients treated with LINAC-based single-fraction SRS for their benign brain lesions were included. A neurosurgeon and two radiation oncologists retrospectively reviewed all data. Computed tomography (CT) simulation was performed after head-frame fixation under local anesthesia. All planning CT images were co-registered and fused with gadolinium-enhanced magnetic resonance imaging taken within 3 months for lesions targeting and critical organs delineation. The marginal dose was prescribed at 60%-90% isodose lines, respectively, to cover ≥95% planning target volume. Outcome evaluations included clinical tumor control rate (TCR), defined as the need for salvage therapy, and radiological response, defined as no enlargement of >2 cm in the maximal diameter. Overall survival (OS) and adverse reaction (defined according to CTCAE 5.0) were also analyzed.

Results

The present study included 76 female and 51 male patients for analysis. The median age was 59 years (range, 20-88 years). Their diagnoses were vestibular schwannoma (VS, n = 54), nonvestibular cranial nerve schwannoma (n = 6), meningioma (n = 50), and pituitary adenoma (n = 17). Totally 136 lesions were treated in a single fraction, predominantly skull base tumors, accounting for 69.1%. Median and mean follow-up duration was 49 and 61 months (range, 1-214 months), Overall TCR was 92.9%. The 5-year disease-specific TCR for VS, nonvestibular schwannoma, meningioma, and pituitary adenoma were 97.4%, 91.7%, 93.8%, and 83.3%. Salvage therapy was indicated for eight patients at 4-110 months after SRS. Among symptomatic patients, post-SRS symptom(s) was improved, stable, and worse in 68.2%, 24.3%, and 3.6%, respectively. Radiological response rate for 111 evaluable patients was 94.6% (shrinkage, 28.8%; stable, 65.8%). OS was 96.1% without treatment-related mortality. One patient with post-SRS cranial nerve injury (0.8%, involving the trigeminal nerve, grade 2 toxicities). No grade 3-4 acute or late toxicity was found.

Conclusion

Our results suggested that LINAC-based SRS effectively controls tumor growth and tumor-related neurological symptoms for patients with benign brain tumors. SRS is less aggressive, associated with low neurological morbidity and no mortality. Continuous follow-up is indicated to conclude longer outcomes.

Radiosurgery for Five to Fifteen Brain Metastases: A Single Centre Experience and a Review of the Literature

Purpose

Stereotactic radiosurgery (SRS) is now mainstream for patients with 1-4 brain metastases however the management of patients with 5 or more brain metastases remains controversial. Our aim was to evaluate the clinical outcomes of patients with 5 or more brain metastases and to compare with published series as a benchmarking exercise.

Methods

Patients with 5 or more brain metastases treated with a single isocentre dynamic conformal arc technique on a radiosurgery linac were identified from the institutional database. Endpoints were local control, distant brain failure, leptomeningeal disease and overall survival. Dosimetric data were extracted from the radiosurgery plans. Series reporting outcomes following SRS for multiple brain metastases were identified by a literature search.

Results

36 patients, of whom 35 could be evaluated, received SRS for 5 or more brain metastases between February 2015 and October 2021. 25 patients had 5-9 brain metastases (group 1) and 10 patients had 10-15 brain metastases (group 2). The mean number of brain metastases in group 1 was 6.3 (5-9) and 12.3 (10-15) in group 2. The median cumulative irradiated volume was 4.6 cm³ (1.25-11.01) in group 1 and 7.2 cm³ (2.6-11.1) in group 2. Median follow-up was 12 months. At last follow-up, local control rates per BM were 100% and 99.8% as compared with a median of 87% at 1 year in published series. Distant brain failure was 36% and 50% at a median interval of 5.2 months and 7.4 months after SRS in groups 1 and 2 respectively and brain metastasis velocity at 1 year was similar in both groups (9.7 and 11). 8/25 patients received further SRS and 7/35 patients received whole brain radiotherapy. Median overall survival was 10 months in group 1 and 15.7 months in group 2, which compares well with the 7.5 months derived from the literature. There was one neurological death in group 2, leptomeningeal disease was rare (2/35) and there were no cases of radionecrosis.

Conclusion

With careful patient selection, overall survival following SRS for multiple brain metastases is determined by the course of the extracranial disease. SRS is an efficacious and safe modality that can achieve intracranial disease control and should be offered to patients with 5 or more brain metastases and a constellation of good prognostic factors.

Central Nervous System Metastases from Triple-Negative Breast Cancer: Current Treatments and Future Prospective

It is estimated that approximately one-third of patients with triple-negative breast cancer (TNBC) will develop brain metastases. The prognosis for patients with breast cancer brain metastasis has improved in the recent past, especially for hormone receptor and human epidermal growth factor receptor 2 (HER) positive subtypes. However, the overall survival rate for patients with triple-negative subtype remains poor. The development of newer treatment options, including antibody-drug conjugates such as Sacituzumab govitecan, is particularly encouraging. This article reviews the clinical outcomes, challenges, and current approach to the treatment of brain metastasis in TNBC. We have also briefly discussed newer treatment options and ongoing clinical trials. The development of brain metastasis significantly decreases the quality of life of patients with TNBC, and newer treatment strategies and therapeutics are the need of the hour for this disease subgroup.

The development and testing of a novel spherical radiotherapy phantom system for the commissioning and patient-specific quality assurance of mono-isocentric multiple mets SRS plans

PURPOSE

To develop a single radiotherapy phantom system capable of performing both patient-specific quality assurance (QA) measurements and commissioning measurements for mono-isocentric LinAc-based stereotactic radiosurgery ("mLSRS") treatment plans.

METHODS

Design A 20-cm diameter spherical phantom was designed which contained within it a film cartridge. The surface of the sphere was machined to display a set of angular markings at both the equator and the meridian representing a spherical coordinate system. A stand was designed which allows for free rotation about any vector passing through the center of the sphere. A program was created using Python 3 to: (a) Compute the measurement setup necessary to intersect exactly one film plane with three user specified dicom points contained within the QA plan; (b) Extract the intersection dose plane from the three dimensional DICOM dose file and; (c) Generate a synthetic computed tomography (CT) in the exact measurement geometry which is subsequently used for phantom positioning during the QA measurement.

TESTING

To assess the functionality of the phantom system dynamic conformal arc mLSRS plans that were generated by a clinically commissioned multiple metastasis treatment planning system (BrainLab Elements version 2.0) using patient-specific data. A total of seven patient plans were created that contained a total of 31 targets {<Volume> = (0.382 ± 0.534) cc: Range [0.051, 2.05] cc, <Off-Axis Distance> = (30 ± 16) mm: Range[0, 55] mm} 27 of which were directly measured with film and analyzed. Each planned isocenter was mapped to the phantom's center and the dose was recomputed. From the phantom dose distribution dicom points of interest were selected in sets of three and input into the provided software. The software computed the plane that intersects with the entered three points and instructed the user on the setup geometry to place the film in the intersecting plane. The software then generated a synthetic CT scan with embedded fiducial markers rotated into the setup orientation. This CT was then used as the setup reference image in ExacTrac image guidance system (tolerance 0.7 mm & 0.5deg). All plans were delivered on a Varian Truebeam linear accelerator with HDMLC, Exactrac and a 6 degree of freedom couch. After delivery of each test plan a 10 × 10 reference field was delivered to a known dose approximately equal to the maximum dose contained within the plan for film calibration. The test film was scanned simultaneously with the 10 × 10 reference film and a film that received zero dose using an Epson 10000XL flatbed scanner after waiting 24 hours. The test film was scaled according to the reference film and analyzed via the gamma analysis (3%, 1 mm, 10%) implemented in Ashland Film QA Pro software.

RESULTS

The spherical phantom system was able to perform validation measurements on a variety of patient-specific plan geometries. The average gamma pass-rate γ(3%, 1 mm,10%) for all measurements was 96.7% (σ = 3.6%).

CONCLUSIONS

A novel spherical radiotherapy phantom system has been designed and tested on clinically relevant test plans.

Whole-brain irradiation with hippocampal sparing and dose escalation on metastases: neurocognitive testing and biological imaging (HIPPORAD) - a phase II prospective randomized multicenter trial (NOA-14, ARO 2015-3, DKTK-ROG)

BACKGROUND

Whole brain radiation therapy (WBRT) is the standard therapy for multiple brain metastases. However, WBRT has a poor local tumor control and is associated with a decline in neurocognitive function (NCF). Aim of this trial is to assess the efficacy and safety of a new treatment method, the WBRT with hippocampus avoidance (HA) combined with the simultaneous integrated boost (SIB) on metastases/resection cavities (HA-WBRT+SIB).

METHODS

This is a prospective, randomized, two-arm phase II multicenter trial comparing the impact of HA on NCF after HA-WBRT+SIB versus WBRT+SIB in patients with multiple brain metastases. The study design is double-blinded. One hundred thirty two patients are to be randomized with a 1:1 allocation ratio. Patients between 18 and 80 years old are recruited, with at least 4 brain metastases of solid tumors and at least one, but not exceeding 10 metastases ≥5 mm. Patients must be in good physical condition and have no metastases/resection cavities in or within 7 mm of the hippocampus. Patients with dementia, meningeal disease, cerebral lymphomas, germ cell tumors, or small cell carcinomas are excluded. Previous irradiation and resection of metastases, as well as the number and size of metastases to be boosted have to comply with certain restrictions. Patients are randomized between the two treatment arms: HA-WBRT+SIB and WBRT+SIB. WBRT is to be performed with 30 Gy in 12 daily fractions and the SIB with 51 Gy/42 Gy in 12 daily fractions on 95% of volume for metastases/resection cavities. In the experimental arm, the dose to the hippocampi is restricted to 9 Gy in 98% of the volume and 17Gy in 2% of the volume. NCF testing is scheduled before WBRT, after 3 (primary endpoint), 9, 18 months and yearly thereafter. Clinical and imaging follow-ups are performed 6 and 12 weeks after WBRT, after 3, 9, 18 months and yearly thereafter.

DISCUSSION

This is a protocol of a randomized phase II trial designed to test a new strategy of WBRT for preventing cognitive decline and increasing tumor control in patients with multiple brain metastases.

TRIAL REGISTRATION

The HIPPORAD trial is registered with the German Clinical Trials Registry (DRKS00004598, registered 2 June 2016).