An Analysis of Risk Factors for Cerebral Radiation Necrosis Following Stereotactic Radiosurgery

Purpose: Cerebral radiation necrosis is a frequent complication of brain radiation therapy (RT) and is characterized by various neurological symptoms including cognitive dysfunction, headaches, weakness, apraxia, aphasia, and numbness. These symptoms may be progressive and treatment resistant. Currently, risk factors for radiation necrosis are not well characterized. The goal of this study is to identify risk factors for cerebral radiation necrosis in order to improve clinicians’ ability to appropriately weigh the risks and benefits of brain radiation therapy.

Methodology: A retrospective chart review was performed on patients who were diagnosed with brain cancer and who received stereotactic radiation therapy at UAMS from 7/1/2017-7/1/2019. Demographics, characteristics of cancer, chemotherapy status and class, comorbidities, and additional medications of patients were collected via EPIC. Total RT dose, fraction size, volume of brain receiving 12 Gy (V12), and re-treatment of locally recurrent tumors were recorded from Eclipse. The diagnosis of radiation necrosis was based on MRI reports that were examined for a time period of 24 months following the completion of radiation treatment and confirmed when possible by biopsy. Cases that did not have an MRI available at least 2 months after the completion of radiation therapy were excluded. Numerical and binary risk factors were assessed of their associations to radiation necrosis using independent t-tests and Chi-square tests, respectively.

Results: A total of 139 patients were studied. Mean ± standard deviation (or SD) for age was 60.4 ± 13.6 years, female:male ratio was 71:68; and White:African American:Other race ratio was 112:24:3. A total of 43 (30.9%) patients were diagnosed with radiation necrosis. Total dose of radiation therapy and V12 were found to be higher in patients with necrosis (mean ± SD = 7.90 ± 0.49 and 2.56 ± 1.73) than those without necrosis (mean ± SD = 7.66 ± 0.31 and 3.54 ± 2.37, p-values <0.01). Additionally, patients with necrosis were more likely to have concurrent chemotherapy status and radiation therapy adjuvant to surgery than those without necrosis, with odds ratios being 3.23 and 2.29 (p-values = 0.021, and 0.032), respectively.

Conclusions: Our study suggested a positive correlation for concurrent chemotherapy status and post-surgical adjuvant radiation therapy with the incidence of radiation necrosis. It further demonstrated that greater total RT dose and V12 are related to the risk for developing radiation necrosis following brain radiation therapy. Given the findings of this study, the aforementioned factors should be considered when weighing the risk of radiation necrosis with the benefits of treatment.

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