Partial regression of tumor-vessel contact indicates suitability for surgical exploration, irrespective of the degree of decrease in tumor size or the degree of residual vascular involvement.

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Abstracts iii99 NEURO-ONCOLOGY • MAY 2017a median of 25 months (p=0.003). There was a significant difference in progression free survival (PFS) between the two groups calculated from RT till further progression or last follow-up. The 3-year and 5-year PFS of patients in the early adjuvant RT group was 85% and 69% as compared to 49% and 28% in the salvage RT group (p<0.001). At the time of last follow-up, 17 patients had died (6 of 51 in the early adjuvant RT group, 11 of 30 in the salvage RT group). There was no significant difference in overall survival between the two groups calculated from date of first diagnosis. CONCLU-SIONS: Early adjuvant RT significantly improves PFS in patients with atypical meningioma compared to observation (after initial surgical resection) and salvage RT at recurrence/progression. I would like to apply for WFNO travel grant for members of less developed countries and have already registered for EANO membership. P12.20 MENINGIOMAS INVADING THE MAJOR DURAL SINUSES: LONG TERM RESULTS OF ATTEMPTED RADICAL RESECTION AND ADJUVANT TREATMENT AFTER SUBTOTAL RESECTIONS. Park, K. Sung, J. Moon, E. Kim, C. Hong, K. Lee, J. Chang; Yonsei University Health System, Seoul, Korea, Republic of. PURPOSE: Radical resection of meningiomas invading the major dural sinuses remains controversial. In particular, whether the fragment invading the sinus must be resected and whether the venous system must be reconstructed continue to be issues of debate. The aims of this study are to evaluate results of patients with a meningioma infiltrating the major dural sinuses and to discuss our management strategy. MATERIALS AND METHODS: Between 2003 and 2015, 103 patients (75 women and 28 men; mean age, 54.0 ± 13.5 (18-83) year-old) underwent surgery for meningiomas originating at the superior sagittal sinus in 82, the transverse sinus in 12, the sigmoid sinus in 13, and the confluence of sinuses in 6. Meningiomas even if it was adjacent to the sinus and not invading its wall, as well as any tumor potentially detachable from the lateral wall without requiring resection of at least its outer layer, were excluded from this series. Median follow-up duration was 50.4 ± 44.2 (1.3-153.4) months. RESULTS: Total and nearly total resection (grossly total resection) was achieved in 49 (47.5%) of cases. In grossly total resection group, 19 patients with a meningioma totally occluding the major dural sinus had complete resection of the encased portion of the sinus. In the remaining 30 patients, the opened sinus was closed with hemostatic materials or was sutured for repair of sinus wall after the resection of the tumor. The grossly total resection group was better than subtotal resection group in terms of progression free survival. In the subtotal resection group of grade I meningioma patients, performing adjuvant stereotactic radiosurgery (SRS) was effective than follow-up group without adjuvant treatment in considering progression free survival and recurrence rate. CONCLUSIONS: On the basis of our results, we conclude that if th...

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