Role of stereotactic radiosurgery for intracranial epidermoid tumors: a systematic review to assess its safety, efficacy, and complication profile.

Background: Even a gross total resection of a benign epidermoid tumor (ET) carries a high risk of recurrence. The management strategy mostly involves redo surgical excision but at a significant cost of morbidity and mortality. The role of adjuvant radiation therapies in this scenario is still undefined.

Objective: To evaluate the feasibility, safety, efficacy, and complication profile of radiosurgery as a standalone or adjuvant therapy for intracranial epidermoid in the published literature.

Methodology: Following PRISMA guidelines, a comprehensive search of the databases PubMed, Embase, Scopus, and Web of Science in published English language was conducted. We included studies with radiosurgery for benign ET and in patients with malignant transformation of ET (MTET). All studies were evaluated for tumor characteristics, pattern of treatment, dosimetric profile, outcome, and complications. We included all studies with at least one outcome of interest i.e. local control (LC); progression-free survival (PFS); symptomatic toxicity; disease progression; retreatment; and overall survival (OS); and cause-specific mortality.

Results: The search revealed 403 articles, of which 6 and 8 studies with patients of benign ET and MTET respectively were included. 25 (65.7%) patients received primary SRS. 27 patients presented with hyperactive cranial nerve syndromes; 77.7% gained complete improvement. The overall median age was 46.7 years (22-67) and the median tumor volume ranged from 0.38 to 6.2cc in benign ET. Volumetric reduction was seen in 6 cases; progression was seen in 2 cases while ET remained stable in the rest. Mean follow-up duration ranged from 33.7 to 60 months, and no recurrence was reported at the latest follow-up in any case of benign ET. 9.5% of patients suffered from transient cranial nerve deficits with no prolonged adverse radiation effect. OS in the MTET group was 6 to 60 months following GKRS with 50% of patients alive at the latest follow-up.

Conclusion: SRS may be a promising treatment option for a conventionally benign and radioresistant ET making a meaningful change in the natural history of the disease. It is a valuable adjuvant technique in patients with MTET.