Fractionated Volumetric Modulated Arc Therapy (FVMAT) for Oligometastatic Brain Tumor

Abstract

Intracranial metastasis is very common in adult cancer patients with an overall incidence of approximately 10–40%. The most common primary tumors responsible for this in adults are lung and breast cancer. Brain metastasis signifies a grave prognosis, with a median survival of 6 to 12 months. They are traditionally managed with palliative care and whole brain radiotherapy (WBRT). WBRT was an effective method to control brain metastases, decreasing corticosteroid use to control tumor-associated edema, and potentially improving overall survival; however, WBRT was found to be associated with a serious neurocognitive degeneration, this adverse effect (AE) follows a biphasic pattern beginning with a transient decline in mental functioning at around 4 months post-treatment, slowly leading to an irreversible neurologic impairment from months to years later. Evidence supports that WBRT can cause radiation injury to the hippocampus, which in turn will lead to a decline in neurocognitive function (NCF). Volumetric modulated arc therapy (VMAT) is a relatively new type of image-guided radiotherapy that treats multiple brain metastasis simultaneously and efficiently with less neurocognitive sequelae. Eighteen cancer patients with limited (≤5 brain tumors) or oligometastatic brain tumor were treated with a spatially fractionated VMAT technique for a total dose of 30 Gy in 10 fractions, the patients tolerated the VMAT treatment with no radiation-induced neurologic toxicities after a mean follow-up of 1 year. Local control rate was 84%, and the median survival for these 19 patients was 11.3 months (range: 9.1–22.4 months). In conclusion, the VMAT is a suitable technique that is a safe and effective treatment for brain oligometastases.