Radiation necrosis (RN) is common in patients who have undergone stereotactic radiation surgery (SRS) for the treatment of intracranial metastasis (ICM) from melanoma, with poor clinical outcomes, according to research recently published in Clinical Medicine Insights: Oncology.

Researchers conducted a retrospective review of adult patients with melanoma who either underwent SRS alone or a combination of SRS and whole-brain radiation therapy (WBRT) between 2013 and 2018. The collected data for analysis included demographics, tumor characteristics, radiation parameters, prior surgical and systemic treatments, and patient outcomes.

Nearly 92% of the patients received at least 1 systemic therapy prior to radiotherapy, but the researchers found that the type and number of treatments did not significantly vary in patients with radiation necrosis compared with those who do not develop it. Approximately 35% underwent resection prior to SRS.

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The researchers found that radiation necrosis was diagnosed between 1.6 and 38 months after SRS in 27% of the patients. Those who developed radiation necrosis were somewhat younger than those who did not, but the difference wasn’t statistically significant.

The mean time between initial melanoma diagnosis and identification of ICM via an MRI of the brain was 70 months. The period was shorter in patients who didn’t develop radiation necrosis than those who did, and patients with radiation necrosis had a higher average value of lesion size (1.7 cm) than those without a radiation necrosis diagnosis (1.2 cm). But for both, the differences were not statistically significant.

The researchers also found that the median overall survival rate for patients with radiation necrosis was 35 months vs 18 months for patients without radiation necrosis. This may be “a direct result of advances in systemic therapy in combination with improved radiation techniques providing more effective overall disease control,” and as patients live longer, the cumulative risk of radiation necrosis may increase.

The researchers acknowledged a substantial rate of radiation necrosis in patients with metastatic melanoma who undergo stereotactic radiation surgery for treatment of ICM, and that this study didn’t reveal any statistically significant risk factors to predict who will develop radiation necrosis.

“However, there were trends toward larger lesions, prior surgical resection, and a longer period between surgery and adjuvant SRS in patients with intracranial melanoma who developed [radiation necrosis],” they wrote. “Additional work is warranted to discern whether certain chemotherapy regimens convey increased risk of subsequent RN development and whether germline genetics known to influence radiosensitivity play a role in the progression of RN.”

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Thomson HM, Fortin Ensign SP, Edmonds VS, et al. Clinical outcomes of stereotactic radiosurgery-related radiation necrosis in patients with intracranial metastasis from melanomaClin Med Insights Oncol. Published online March 21, 2023. doi:10.1177/11795549231161878