Upfront stereotactic radiosurgery for large posterior fossa metastases: a multicenter evaluation of clinical outcomes

Category	Detail
Condition	Large cerebellar brain metastases
Key Mechanisms	Tumor mass effect causing neurological symptoms; treatment via stereotactic radiosurgery delivering high-dose radiation sparing normal tissue
Target Population	Adult patients (≥18 years) with large cerebellar metastases (≥5 cm³) from solid tumors, often poor surgical candidates or those declining surgery
Care Setting	Multidisciplinary oncology centers with stereotactic radiosurgery capability

Large cerebellar metastases pose risks due to proximity to brainstem and fourth ventricle, causing symptoms like headaches, nausea, ataxia, and hydrocephalus.
Surgical resection offers rapid mass effect relief but carries high complication rates (10–30%) including neurological deficits and CSF leakage.
Upfront stereotactic radiosurgery (SRS) is a non-invasive alternative with favorable local control (~85% at 1 year) and median survival (~12 months), with lower severe complication rates (5–15%).

Use contrast-enhanced T1-weighted brain MRI to measure tumor volume and assess peritumoral edema and fourth ventricle compression.
Evaluate clinical status including neurological symptoms and ECOG performance status.

Consider surgical resection for large, symptomatic lesions requiring urgent decompression.
Use upfront stereotactic radiosurgery (single-fraction or fractionated) for large cerebellar metastases ≥5 cm³, especially in poor surgical candidates or those declining surgery.
Reserve whole-brain radiotherapy for patients with extensive intracranial disease or limited life expectancy.

Perform serial MRI scans post-SRS to assess tumor response and monitor for radiation-induced edema or necrosis.
Monitor neurological status and manage treatment-related complications medically; consider surgical intervention if severe complications arise.

Surgical resection risks include leptomeningeal dissemination, infection, hemorrhage, neurological deficits, and CSF leakage.
SRS risks include radiation-induced edema and necrosis, with severe complications requiring surgery in 5–15% of cases.

Adults with large cerebellar metastases treated with upfront SRS at two tertiary centers between 2007 and 2024.

Upfront SRS is feasible and effective in selected patients, providing local control and survival benefits while minimizing surgical morbidity.

Integrate multidisciplinary evaluation including neurosurgery, radiation oncology, and medical oncology for treatment planning.
Use high-resolution MRI fused with CT for precise target delineation in SRS planning.
Select fractionated or single-fraction SRS based on tumor size, location, and patient factors.
Employ patient-specific immobilization devices (rigid thermoplastic masks) for treatment accuracy.
Manage corticosteroid use post-treatment to control edema and symptoms.

Clinical Scorecard: Initial Stereotactic Radiosurgery for Large Cerebellar Metastases: A Multicenter Assessment of Clinical Outcomes