Abstract
BACKGROUND
Subependymal giant cell astrocytoma (SEGA) is a low-grade glioma that occurs in patients with tuberous sclerosis complex (TSC). SEGA typically grows within the ventricles causing hydrocephalus and sudden death. Surgical resection is the traditionally preferred treatment and expert opinion advises strongly against the use of radiotherapy, insomuch that it is not even mentioned as a treatment option in reviews or guidelines. Nevertheless, surgical resection of big volume or bilaterally growing SEGA can be very challenging. Recently, success has been reported with the use of mTOR inhibitor, everolimus, in reducing tumor volume. However, regrowth was observed after drug cessation requiring long-term if not life-long drug administration and thus raising concerns regarding side effects and high treatment costs. Here, we report about a case with inoperable bilateral SEGA that was successfully treated with fractionated stereotactic radiotherapy alone (30x2Gy) with a follow up period of 8 years before being treated with everolimus for renal involvement of TSC. Currently, the patient has been followed up for 13 years.
MATERIAL AND METHODS
All of the patient’s pre and post treatment MRI’s were used for detailed volumetric assessment of the response of the SEGA on each side separately. Systematic review of the literature was conducted via PubMed and Up-to-date using the search terms: ‘treatment of SEGA’, ‘radiotherapy in SEGA’, ‘SRS in SEGA’, ‘treatment of tuberous sclerosis complex’, ‘radiotherapy treatment in low grade astrocytoma’, etc. The article references were queried for the terms ‘radiotherapy’, ‘induced tumors’ and ‘malignant tumors’. Secondary references were added to the database and reprocessed similarly. Reviews about radiation-induced tumors were also added to the database. Attention was given to reports containing data about irradiated SEGA and about high-grade brain tumors in TSC patients. The database was locked on 1-02-2018 containing 1298 article references and 780 full-text articles.
RESULTS
In our case, the successive volumetric assessments on MRI’s demonstrated 80% volume reduction after radiotherapy alone, further enhanced to 90% after everolimus administration. Literature review shows no valid evidence for contra-indicating fractionated stereotactic radiotherapy in SEGA and shows that surgery is still associated with high re-operation and post-operative complications rates.
CONCLUSION
A slow progressive response of SEGA on both sides to radiotherapy was observed similar to the response seen in other benign intracranial tumors. We believe that stereotactic radiotherapy alone or sequentially combined with everolimus deserves to be studied as an alternative to resection in difficult cases that do not require immediate volume reduction.
Rare case of subependymal giant cell astrocytoma without clinical features of tuberous sclerosis: Case report and literature review