Radiation-induced glioma following CyberKnife® treatment of metastatic renal cell carcinoma: a case report

Post-stereotactic radiation-induced neoplasms, although relatively rare, have raised the question of benefit regarding CyberKnife® treatments versus the risk of a secondary malignancy. The incidence of such neoplasms arising in the nervous system is thought to be low, given the paucity of case reports regarding such secondary lesions. Here we describe a case of a 43-year-old Middle Eastern woman with primary clear cell renal cell carcinoma and a metastatic focus to the left brain parenchyma who presented with focal neurologic deficits. Following post-surgical stereotactic radiation in the region of the brain metastasis, the patient developed a secondary high-grade astrocytoma nearly 5 years after the initial treatment. Although the benefit of CyberKnife® radiotherapy treatments continues to outweigh the relatively low risk of a radiation-induced secondary malignancy, knowledge of such risks and a review of the literature are warranted.