Treatment Outcomes of World Health Organization Grade 2 (Atypical) Meningiomas After Surgery With or Without Postoperative Upfront Radiation Therapy

Abstract

The role of postoperative radiation therapy for World Health Organization (WHO) grade II meningiomas has been controversial. We evaluated long-term treatment outcomes in patients with WHO grade II (atypical) meningiomas who had received surgery with or without postoperative radiation therapy. Between 1994 and 2008, 77 patients who underwent resection of WHO grade II meningiomas were reviewed retrospectively. Grade of meningiomas was defined using 2007 WHO criteria by a single neuropathologist. The median age at diagnosis was 52 years (range, 15-77 years). They were 27 male and 50 female. The degree of tumor resection was as follows: Simpson grade 1 in 28 (36.4%), grade 2 in 28 (36.4%), grade 3 in 7 (9.1%), and grade 4 in 14 (18.2%) patients, respectively. Nineteen patients received postoperative upfront radiation therapy according to the surgeons' preferences with the median dose of 5940 cGy (range, 3800-6200 cGy). The median follow-up was 86.7 months (range, 2.1-181.9 months). The 5- and 10-year overall survival rates were 84.4% and 72.8%, respectively. The 5- and 10-year local relapse free survival (LRFS) rates were 62.7% and 47.7%, respectively. The degree of tumor resection was an important factor in predicting tumor recurrence. The 5-year LRFS was 88.9% in patients received Simpson grade 1 resection and 48.0% in Simpson grade 2-4 resection (p < 0.005). Although the incidence of tumor recurrence was not significant according to postoperative upfront radiation therapy in all patients (5-year LRFS: 76.6% vs. 57.9%, p = 0.075), significant difference in local recurrence was observed in patients who received Simpson grade 2-4 resection with or without postoperative upfront radiation therapy (5-year LRFS: 80.2% vs. 37.0%, p = 0.006). The degree of surgical resection was a significant parameter affecting LRFS in patients with WHO grade II meningiomas. Postoperative upfront radiation therapy also demonstrated a significant benefit of reducing tumor recurrence when patients had undergone Simpson grade 2-4 resection. Well-designed prospective study is needed to make a definitive conclusion in regarding to the role of postoperative upfront radiation therapy in patients with WHO grade II meningiomas.