Extent of Surgical Resection of Epidermoid Tumors Affects Risk of Recurrence: Results of the Largest Meta-analysis of 691 Patients

Introduction: Neurosurgical resection of epidermoid tumors can be quite challenging and potentially morbid, leading to questions surrounding extent of resection. In the largest meta-analysis to date of patients with epidermoid tumors, we compared recurrence rates for STR and GTR and the associated complications. Methods: A systemic literature review following the PRISMA guidelines was completed followed by a proportional meta-analysis to compare the pooled recurrence rates between STR and GTR in epidermoid tumors. Fixed- and mixed-effect models were used to compare the pooled proportions of recurrence after STR or GTR. The relationship between recurrence rate and follow-up time was studied using linear regression and natural cubic spline models. Results: Twenty-seven studies with 691 patients met our inclusion criteria, among whom, 293 (42%) underwent STR, while 398 (58%) received GTR. The average recurrence rate of all procedures was 11%. The proportional meta-analysis showed that the pooled recurrence rate after STR (21%) was seven times that after GTR (3%). The most common surgical complications were transient cranial nerve palsies, occurring equally in STR and GTR cases when reported. The average recurrence rate for studies with longer follow-up time (>4.4 years) (17.4%) was significantly higher than the average recurrence rate for studies with shorter follow-up time (<4.4 years; 5.7%). Conclusion: STR of epidermoid tumors is associated with a significantly higher rate of recurrence (∼ seven times) compared with GTR and correlates with time such that more recurrences, on average, are observed after longer postoperative periods of time. Types of complications, and their frequencies, do not seem to differ between STR and GTR. Attempts at GTR, when appropriate, should be made during the initial surgery with efforts to optimize success. In all postoperative epidermoid tumor cases, but particularly following STR, close follow-up with serial MRIs, even years after surgery, is recommended.