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Fractionated Stereotactic Radiotherapy (FSR) for Meningiomas Involving or Close to the Optic Apparatus
I. J. Radiation Oncology d Biology d Physics
S254
2090
Volume 69, Number 3, Supplement, 2007
Fractionated Stereotactic Radiotherapy (FSR) for Meningiomas Involving or Close to the Optic Apparatus
R. Pfeffer, D. Alezra, J. Menhel, R. Spiegelmann Sheba Medical Center, Tel-Hashomer, Israel Purpose/Objective(s): To assess the clinical and radiological results of fractionated stereotactic radiation (FSR) in the treatment of meningioma involving or close to the optic apparatus, treated at Sheba Medical Center since beginning our FSR program in November 2002. Patients with either optic nerve sheath meningioma or skull base meningioma situated within 5 mm of the optic tract were selected for FSR. Patients with skull base meningioma .5 mm from the optic tract received single fraction radiation (radiosurgery) and are not included in this study. Materials/Methods: The treatment protocol was for a total radiation dose of 50.4–54 Gy in daily fractions of 1.8 Gy calculated to the 90% isodose line. The prescription dose covered the entire GTV and at least 95% of the PTV. The PTV included all GTV with 3 mm margins. The maximum optic nerve dose was limited to 56 Gy. Patients were immobilized in a removable frame and underwent MRI with 1 mm slices and CT planning after image fusion. Planning was performed on a BrainLab system. Treatment was delivered using dynamic arcs (typically 4 arcs) with the M3 micro-multileaf collimator. Seventy five consecutive patients were treated until November 2006 and have been followed up for at least six months. Seventeen patients with optic nerve sheath (ons) meningioma and 58 patients with skull base meningioma (predominant sites: 37 cavernous sinus, 6 clinoid, 5 orbital apex, 5 petroclival, 5 parasellar) were treated. Age ranged from 26–75 years (median 55 years). All patients with ons meningioma and 19 of the remaining patients presented with visual symptoms. 31 patients with non ons meningiomas had undergone previous surgery. Patients were followed for 6–54 (median 26) months. Follow up was by clinical symptoms, ophthalmologic exam and annual MRI. Results: Acute toxicity was mild and limited to fatigue (11 patients) headaches (3 patients) and nausea (1 pt) and responded to low dose dexamethasone in all patients. Of the 36 patients with visual symptoms, vision improved in 23 (64%), was stable in 11 (30%) and worsened in 2 patients. Eleven patients reported subjective visual improvement on completion of their radiotherapy course and in most responding patients improved vision was noted within 6 months of completing radiotherapy. No visual impairment was seen in patients presenting without visual symptoms. Fifty eight patients have undergone MRI one year following treatment, none have shown tumor progression. Conclusions: Within the limitations of the short follow up of our series, FSR is an effective and safe treatment for patients with optic nerve sheath or skull base meningioma involving or close to the optic pathway. Author Disclosure: R. Pfeffer, None; D. Alezra, None; J. Menhel, None; R. Spiegelmann, None.
2091
Neural Stem Cell (NSC)–Preserving External Beam Radiotherapy of Central Nervous System Malignancies
I. J. Barani, L. W. Cuttino, S. H. Benedict, D. A. Todor, E. A. Bump, Y. Wu, T. D. Chung, W. C. Broaddus Virginia Commonwealth University, Richmond, VA Purpose/Objective(s): Recent discoveries have implicated neural stem cells (NSC) as the source of plasticity and repair in the mature mammalian brain. Treatment-induced NSC dysfunction may lead to observed toxicity. This study evaluates the feasibility of neural stem cell (NSC) preserving external beam radiotherapy. Materials/Methods: A single computed tomography (CT) dataset depicting a right periventricular lesion was used in this study as this location reflects the most problematic geometric arrangement with respect to NSC preservation. Conventional and NSC preserving radiotherapy (RT) plans were generated for the same lesion using two clinical scenarios: cerebral metastatic disease and primary high-grade glioma. Disease-specific target volumes were used. Metastatic disease was conventionally treated with wholebrain radiotherapy (WBRT) to 3750 cGy (15 fractions) followed by a single stereotactic radiosurgery (SRS) boost of 1800 cGy to gross disease only. High-grade glioma was treated with conventional opposed lateral and anterior superior oblique beams to 4600 cGy (23 fractions) followed by a 1400 cGy (7 fractions) boost. NSC preservation was achieved in both scenarios with inverse planned intensity modulated radiotherapy (IMRT) (Fig.). Results: Cumulative dose reductions of 65% (metastatic disease) and 25% (high-grade glioma) to the total volume of the intracranial NSC compartments were achieved with NSC-preserving IMRT plans. The reduction of entry and exit dose to NSC niches located contralateral to the target contributed most to NSC preservation. Conclusions: NSC preservation with current external beam radiotherapy techniques is achievable in context of both metastatic brain disease and high-grade glioma, even when the target is located adjacent to a stem cell compartment. Further investigation with clinical trials is warranted to evaluate whether NSC preservation will result in reduced toxicity.
S254
2090
Volume 69, Number 3, Supplement, 2007
Fractionated Stereotactic Radiotherapy (FSR) for Meningiomas Involving or Close to the Optic Apparatus
R. Pfeffer, D. Alezra, J. Menhel, R. Spiegelmann Sheba Medical Center, Tel-Hashomer, Israel Purpose/Objective(s): To assess the clinical and radiological results of fractionated stereotactic radiation (FSR) in the treatment of meningioma involving or close to the optic apparatus, treated at Sheba Medical Center since beginning our FSR program in November 2002. Patients with either optic nerve sheath meningioma or skull base meningioma situated within 5 mm of the optic tract were selected for FSR. Patients with skull base meningioma .5 mm from the optic tract received single fraction radiation (radiosurgery) and are not included in this study. Materials/Methods: The treatment protocol was for a total radiation dose of 50.4–54 Gy in daily fractions of 1.8 Gy calculated to the 90% isodose line. The prescription dose covered the entire GTV and at least 95% of the PTV. The PTV included all GTV with 3 mm margins. The maximum optic nerve dose was limited to 56 Gy. Patients were immobilized in a removable frame and underwent MRI with 1 mm slices and CT planning after image fusion. Planning was performed on a BrainLab system. Treatment was delivered using dynamic arcs (typically 4 arcs) with the M3 micro-multileaf collimator. Seventy five consecutive patients were treated until November 2006 and have been followed up for at least six months. Seventeen patients with optic nerve sheath (ons) meningioma and 58 patients with skull base meningioma (predominant sites: 37 cavernous sinus, 6 clinoid, 5 orbital apex, 5 petroclival, 5 parasellar) were treated. Age ranged from 26–75 years (median 55 years). All patients with ons meningioma and 19 of the remaining patients presented with visual symptoms. 31 patients with non ons meningiomas had undergone previous surgery. Patients were followed for 6–54 (median 26) months. Follow up was by clinical symptoms, ophthalmologic exam and annual MRI. Results: Acute toxicity was mild and limited to fatigue (11 patients) headaches (3 patients) and nausea (1 pt) and responded to low dose dexamethasone in all patients. Of the 36 patients with visual symptoms, vision improved in 23 (64%), was stable in 11 (30%) and worsened in 2 patients. Eleven patients reported subjective visual improvement on completion of their radiotherapy course and in most responding patients improved vision was noted within 6 months of completing radiotherapy. No visual impairment was seen in patients presenting without visual symptoms. Fifty eight patients have undergone MRI one year following treatment, none have shown tumor progression. Conclusions: Within the limitations of the short follow up of our series, FSR is an effective and safe treatment for patients with optic nerve sheath or skull base meningioma involving or close to the optic pathway. Author Disclosure: R. Pfeffer, None; D. Alezra, None; J. Menhel, None; R. Spiegelmann, None.
2091
Neural Stem Cell (NSC)–Preserving External Beam Radiotherapy of Central Nervous System Malignancies
I. J. Barani, L. W. Cuttino, S. H. Benedict, D. A. Todor, E. A. Bump, Y. Wu, T. D. Chung, W. C. Broaddus Virginia Commonwealth University, Richmond, VA Purpose/Objective(s): Recent discoveries have implicated neural stem cells (NSC) as the source of plasticity and repair in the mature mammalian brain. Treatment-induced NSC dysfunction may lead to observed toxicity. This study evaluates the feasibility of neural stem cell (NSC) preserving external beam radiotherapy. Materials/Methods: A single computed tomography (CT) dataset depicting a right periventricular lesion was used in this study as this location reflects the most problematic geometric arrangement with respect to NSC preservation. Conventional and NSC preserving radiotherapy (RT) plans were generated for the same lesion using two clinical scenarios: cerebral metastatic disease and primary high-grade glioma. Disease-specific target volumes were used. Metastatic disease was conventionally treated with wholebrain radiotherapy (WBRT) to 3750 cGy (15 fractions) followed by a single stereotactic radiosurgery (SRS) boost of 1800 cGy to gross disease only. High-grade glioma was treated with conventional opposed lateral and anterior superior oblique beams to 4600 cGy (23 fractions) followed by a 1400 cGy (7 fractions) boost. NSC preservation was achieved in both scenarios with inverse planned intensity modulated radiotherapy (IMRT) (Fig.). Results: Cumulative dose reductions of 65% (metastatic disease) and 25% (high-grade glioma) to the total volume of the intracranial NSC compartments were achieved with NSC-preserving IMRT plans. The reduction of entry and exit dose to NSC niches located contralateral to the target contributed most to NSC preservation. Conclusions: NSC preservation with current external beam radiotherapy techniques is achievable in context of both metastatic brain disease and high-grade glioma, even when the target is located adjacent to a stem cell compartment. Further investigation with clinical trials is warranted to evaluate whether NSC preservation will result in reduced toxicity.