Innovative Diagnostic and Therapeutic Approaches for Radiation Necrosis.

Area of Science:

• Neurology
• Radiation Oncology
• Oncologic Imaging

Background:

• Radiation necrosis (RN) is a significant complication of stereotactic radiosurgery (SRS) for brain metastases, occurring in 5-25% of patients.
• RN is a late effect, typically emerging 6-12 months post-treatment, with incidence expected to increase due to improved survival.
• The underlying radiobiological mechanisms involve vascular injury, ischemia, neuroinflammation, and fibrosis.

Purpose of the Study:

• To review the current understanding of radiation necrosis (RN) following stereotactic radiosurgery (SRS) for brain metastases.
• To discuss diagnostic challenges and limitations in differentiating RN from tumor progression (TP).
• To explore current and future strategies for RN prevention and management.

Main Methods:

• Review of existing literature on radiation necrosis (RN) and stereotactic radiosurgery (SRS).
• Analysis of diagnostic modalities including MRI (perfusion, spectroscopy) and PET/CT.
• Evaluation of treatment strategies, including steroids, bevacizumab, laser interstitial thermal therapy (LITT), and resection.

Main Results:

• Current diagnostic tools (MR perfusion, MR spectroscopy, Amino Acid PET/CT) have limited specificity and utility in distinguishing RN from TP.
• Steroids are the first-line treatment for symptomatic RN, with bevacizumab or local therapies for refractory cases.
• Refining normal brain tissue dose tolerances and integrating risk stratification tools like Recursive Partitioning Analysis (RPA) are key for prevention.

Conclusions:

• Improved understanding of RN pathophysiology and development of novel therapies are essential.
• Enhanced risk stratification and prevention strategies are critical to minimize RN incidence after SRS.
• These advancements aim to improve the quality of life for patients with brain metastases undergoing SRS.