Radiotherapy for subependymal giant cell astrocytoma: time to challenge a historical ban? Case report and review of the literature.

Background Subependymal giant cell astrocytoma is a deep-seated benign but life-threatening brain tumor that occurs in patients with the tuberous sclerosis complex. Resection is the traditional treatment and expert opinion is strongly against the use of radiotherapy. Systematic epidemiological studies, however, demonstrate high rates of complications and recurrences. The need for efficient non-surgical treatment is best illustrated by the considerable enthusiasm about the activity of the mTOR inhibitor everolimus in reducing tumor volume. Unfortunately regrowth is frequent after dose reduction or cessation and continued tumor control requires continued administration of the drug, leading to concerns about its metabolic and immunosuppressive side effects and cost of treatment. Results We successfully treated a case with growing bilateral subependymal giant cell astrocytoma with fractionated stereotactic radiotherapy before everolimus became available. After a follow-up of 8 years, everolimus was administered for renal angiomyolipoma and the patient was followed up until 13 years after radiotherapy. Successive MRI's demonstrated an 80% volume reduction after radiotherapy that further increased to 90% during everolimus administration. In order to review the basis for the strong expert opinion against radiotherapy, we performed an exhaustive literature study regarding efficiency, potential dangers and side effects of radiation. 1298 article references and 780 full-text articles in search of evidence for contra-indicating radiotherapy. Varying short-term tumor control of single-fraction radiosurgery were described in a total of 13 cases. Only in two published cases the radiation dose of fractionated radiotherapy was mentioned. A single publication mentions an induced secondary brain tumor 8 years after total brain irradiation. Conclusion There is no evidence for contra-indicating fractionated radiotherapy in subependymal giant cell astrocytoma. Our experience demonstrates that these tumors, as other benign intracranial tumors, responds slowly to radiotherapy and suggests that fractionated stereotactic radiotherapy holds promise to consolidate responses obtained with mTOR inhibitors avoiding regrowth after cessation. This combined treatment would avoid costs and complications of long-term treatment with everolimus and deserves to be studied as a definitive non-surgical treatment.