Risk factors for recurrences after Gamma Knife radiosurgery of intracranial meningiomasVincent Bulthuis1, Patrick Hanssens2, Suan Te Lie2, Fons Kessels3, Koo Van Overbeeke11Maastricht, Netherlands 2Gamma Knife Center, St Elisabeth Ziekenhuis, Tilburg, The Netherlands 3Department of Clinical Epidemiology and MTA, Maastricht Universitair Medisch Cen Keywords: meningioma, radiosurgery, gamma knife, outcome, recurrent disease
Gamma Knife radiosurgery (GKRS) is a well established treatment for intracranial meningiomas. Regrowth of treated tumors occurs in about 10% of the patients. Apart from histopathology as a known risk factor for regrowth, the importance of other patient, tumor or treatment planning related factors, like involving the dural tail in the plan, are not clearly defined.
We reviewed the results of our center to access the risk factors for regrowth of mengiomas after GKRS.
Between June 2002 and April 2008, 246 patients with 297 meningiomas were treated in our center.
The median tumor volume was 4,5cc. Median follow up period was 61 months The dural tail was not included in the treatment plan. Based on the diagnosis of a meningioma, 2 groups were distinguished: Group A: There were 115 patients with 118 meningiomas without previous treatment. The diagnosis was based upon defined MRI-characteristics Group B: 131 patients with 179 meningiomas had surgery prior to the first GKRS. 125 (69.8%) tumors were classified as WHO I, 49 (27.4%) as WHO II and 5 (2, 8%) as WHO III
Group A: Progression of 7 of 118 meningiomas resulted in a overall local control rate of 93,9%.No significant risk factors for progression were indentified. Group B: In 26 of 179 meningiomas progression was documented. For WHO grade I meningiomas the overall local control rate was 90,1% . In WHO grade II and III meningiomas, the overall recurrence rate was 46, 7%. Risk factors indentified in this group were: (1) WHO II/III histology, (2) prior surgery with additional treatment, (3) >1 meningioma treated in one session. No tumor recurrences were seen at the dural tail.
This was a retrospective study.
No histological verification is needed to treat benign meningiomas with GKRS when MRI criteria are respected. Tumor histology is a known risk factor for regrowth which is confirmed in this study.
In our study, the dural tail was not involved in the treatment plan. No
recurrences were seen at the dural tail. In our opinion it is not
necessary to involve the dural tail in the treatment plan. Project Roles:
V. Bulthuis (), P. Hanssens (), S. Lie (), F. Kessels (), K. Van Overbeeke ()