Leukoencephalopathy After Stereotactic Radiosurgery for Brain Metastases

Area of Science:

• Neurology
• Radiation Oncology
• Neuro-oncology

Background:

• Stereotactic radiosurgery (SRS) is increasingly used for brain metastases to mitigate neurocognitive deficits associated with whole brain radiation therapy (WBRT).
• The long-term neurocognitive effects and radiation-induced central nervous system damage, specifically leukoencephalopathy, from multiple SRS sessions are not well understood.
• Leukoencephalopathy serves as a sensitive indicator of radiation-induced brain injury.

Purpose of the Study:

• To identify clinical and dosimetric predictors of leukoencephalopathy following SRS for brain metastases.
• To evaluate the cumulative neurocognitive effects of repeated SRS treatments.

Main Methods:

• Retrospective review of 103 patients who received at least two SRS sessions for brain metastases between 2007 and 2013.
• Analysis of pre- and post-SRS MRI scans to grade white matter changes indicative of radiation leukoencephalopathy.
• Cox proportional hazards modeling to identify contributing patient characteristics and SRS dosimetric parameters.

Main Results:

• The incidence of leukoencephalopathy was 29% at 1 year, 38% at 2 years, and 53% at 3 years post-SRS.
• Three significant predictors of leukoencephalopathy were identified: prior whole brain radiation therapy (WBRT), higher SRS integral dose to the cranium, and a greater number of intracranial metastases.
• WBRT significantly increased the rate of leukoencephalopathy compared to SRS alone.

Conclusions:

• Combined WBRT and SRS treatment leads to a substantially higher incidence of leukoencephalopathy than SRS alone.
• For patients treated with SRS without prior WBRT, the integral radiation dose is a key factor in developing leukoencephalopathy.
• As patient survival with brain metastases improves, understanding and mitigating these risk factors for neurotoxicity is crucial.