NCOG-56. THE NATURAL COURSE OF ATYPICAL MENINGIOMA AFTER GROSS TOTAL RESECTION WITHOUT ADJUVANT TREATMENT

Abstract

Abstract Atypical meningioma represent more aggressive clinical behaviors than WHO grade I meningiomas. In this study, We research natural course of atypical meningioma after gross total resection without adjuvant treatment. MATERIAL AND METHODS: We retrospectively reviewed the records of patients with histopathologically diagnosed atypical meningiomas between June 1990 and December 2015 at Asan Medical Center, Korea. Patients treated with Simpson grade I, II resection were included. Patients variably underwent adjuvant radiation therapy according to each surgeon’s preferences. RESULTS: In this study, 117 patients were enrolled and the average follow-up was 43 months (range 3~228 months). In Simpson grade I tumor resection group, recurrence was confirmed in 10 out of 63 patients without adjuvant treatment, and 1 out of 13 patients with adjuvant radiation treatment. There were 12 recurrence cases in Simpson grade II tumor resection and no adjuvant treatment group, of the total 32 cases. There was 4 recurrence case of total 8 cases of Simpson grade II tumor resection with adjuvant radiation treatment group. In groups with no adjuvant treatment, Simpson grade I resection group had a better prognosis on 5-year PFS (82.9% vs 54.9%, p=0.005) compared to Simpson grade II resection group. DISCUSSION: The results of this study show that there is a significant difference in 5-year PFS between the Simpson grade I and II groups without adjuvant treatment, commonly referred to as the gross total resection group. Although this study report adjuvant RT is not superior to observation, more intensive post-operative imaging surveillance protocols would be considered in Simpson grade II resection group without adjuvant treatment. CONCLUSION: The natural course of atypical meningioma after gross total resection without adjuvant treatment signified Simpson grade I and II resection show significant different prognosis.