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Clinical Experience With Radiation Therapy in the Management of Neurofibromatosis-Associated Central Nervous System Tumors
I. J. Radiation Oncology d Biology d Physics
S248
Volume 69, Number 3, Supplement, 2007
Conclusions: Many patients have not required WBRT during their clinical course and so were not at risk of neurocognitive toxicity of WBRT. Our study suggests that postoperative SRS/SRT may be a viable option for patients who have undergone resection of brain metastases. WBRT can be reserved as salvage with acceptable neurological deficit-free survival rates.
Author Disclosure: L. Do, None; R.D. Pezner, None; E. Radany, None; A. Liu, None; C. Staud, None; B. Badie, None.
2081
Clinical Experience With Radiation Therapy in the Management of Neurofibromatosis-Associated Central Nervous System Tumors
S. Wentworth, T. L. Ellis, S. Glazier, K. P. McMullen, V. W. Stieber, S. B. Tatter, E. G. Shaw Wake Forest University, Winston-Salem, NC Purpose/Objective(s): Patients with neurofibromatosis (NF) frequently develop tumors of the central nervous system (CNS). Radiation therapy (RT) is sometimes used in treating these lesions. To better define the efficacy of RT in controlling NF-associated CNS tumors, we reviewed our 20 year experience. Patients/Methods: Seventy-four lesions in 16 patients with NF were treated with RT from 1986–2006. One third of patients had NF1, two thirds NF2. Median follow up was 36 months. Progression was defined as tumor growth or recurrence in an irradiated lesion on serial imaging. Progression free survival was measured from date of treatment to date of last imaging follow up. The actuarial rates of progression free survival were calculated according to the Kaplan Meier method. Results: On average, 5 lesions were treated per patient. The most common indication for treatment was growth on serial imaging. Median age at time of treatment was 24.1 years (range: 4.3–57.1). The treated lesions included acoustic neuromas (9%), ependymomas (7%), low grade gliomas (12%), meningiomas (62%), and non-acoustic schwanommas/neurofibromas (8%). Most patients (62%) received stereotactic radiosurgery. The others received fractionated external beam RT. Overall survival at 5 years for all patients was 94%. Five year progression free survival was 100% (acoustic neuromas), 75% (ependymomas), 100% (low grade gliomas), 86% (meningiomas) and 100% (non-acoustic schwannomas). Most patients with acoustic neuromas were deaf prior to treatment. In those patients with pre-treatment useful hearing, the hearing preservation rate was 0% (Fig.). Conclusions: This is the largest published experience on the results of RT in NF patients with CNS tumors. The progression free survival rates herein are similar or superior to those published for non-NF patients treated with RT. RT should be considered in NF patients with CNS tumors.
Proceedings of the 49th Annual ASTRO Meeting
S249
Author Disclosure: S. Wentworth, None; T.L. Ellis, None; S. Glazier, None; K.P. McMullen, None; V.W. Stieber, None; S.B. Tatter, None; E.G. Shaw, None.
2082
Reliability of Bony Anatomy in Image-Guided Stereotactic Radiotherapy of Brain Metastases
M. P. Flentje, K. Baier, I. Guenther, J. Wilbert, A. Richter, O. Sauer, M. Guckenberger University of Wurzburg, Wurzburg, Germany Purpose/Objective(s): To evaluated whether the position of brain metastases remained stable between planning and treatment in cranial stereotactic radiotherapy (SRT). Materials/Methods: 18 patients with 20 brain metastases were treated with single fraction (n = 17) or hypofractionated (n = 3) image-guided SRT for brain metastases. Patients were immobilized in stereotactic Scotch-cast masks (SC; n = 12) or thermoplastic head masks (TP; n = 8). Prior to treatment a cone-beam CT (CBCT) was acquired and patient set-up was evaluated by automatic image registration with the planning CT; the bony anatomy of the skull was basis for this image registration. Additionally, a conventional CT study was acquired for all patients using an in-room CT scanner: the amount of iv contrast given to the patient and the slice thickness were identical to treatment planning, the table feed was 1 mm. Patient set-up was evaluated based on the position of the brain metastases. Results of bone-match and soft-tissue match for verification of patient set-up were compared. Results: Median time interval between planning and treatment was eight days. Based on automatic bone registration of CBCT and planning CT the 3D positioning errors were 3 mm ± 1.7 mm and 4.6 mm ± 2.1 mm for patients immobilized in SC and TP masks (p = 0.09), respectively. Tumor size was not significantly different between planning and treatment. The 3D set-up error was 4.0 mm ± 2.1 mm and 3.5 mm ± 2.2 mm based on the bony anatomy and the lesion itself, respectively. A highly significant correlation between automatic bone match and soft-tissue registration was seen in all three directions (r $ 0.88). The distance between the iscocentre based on bone match and soft-tissue registration was 1.7 mm ± 0.7 mm, maximum 2.8 mm. Treatment of intracranial pressure with steroids did not influence the position of the lesion relative to the bony anatomy. Conclusions: With a time interval of about one week between planning and treatment the bony anatomy of the skull proved as an excellent surrogate for the target position in image-guided SRT. Own data and data from the literature using 3D-3D image registration for verification of patient set-up suggest that stereotactic head masks are less reproducible for patient positioning than reported with 2D-2D image registration. This further emphasizes the benefit of image-guidance in (fractionated) SRT.
Study 2D-2D image registration for verification of set-up Rosenthal 1995 Hamilton 1996 Theodorou 1998 Alheit 2001 Kalapurakal 2001 Karger 2001 Sweeney 2001 Kumar 2005 Georg 2006 3D-3D image registration for verification of set-up Baumert 2005 Boda-Heggemann 2006 Own study
SRT positioning system
Imaging modality
Positioning error
Dental fixation & thermoplastic mask Scotch cast mask Inhouse frame Brain Lab Mask Laitinen stereotactic localizer & head holder Scotch cast mask Vogele Bale Hohner head holder Gill-Thomas-Cosman Brain Lab Mask
Orthogonal radiographs & Portal imaging Portal imaging Orthogonal radiographs Portal imaging Portal imaging Orthogonal radiographs Portal imaging Portal imaging Portal imaging
2.3 mm ± 1.6 mm # 1.8 mm # \1 mm * \2 mm * #1 mm * 1.2 mm * 1.9 mm ± 1.2 mm # 1.8 mm ± 0.8 mm # 1.3 mm ± 0.9 mm #
Stereotactic mask Scotch cast mask Scotch cast mask
CT Cone-beam CT Cone-beam CT
3.7 mm ± 0.8 mm # 3.1 mm ± 1.5 mm # 3.0 mm ± 1.7 mm #
# 3D error vector (mean ± SD); * largest 2D error in any direction (SD).
Author Disclosure: M.P. Flentje, None; K. Baier, None; I. Guenther, None; J. Wilbert, None; A. Richter, None; O. Sauer, None; M. Guckenberger, None.
S248
Volume 69, Number 3, Supplement, 2007
Conclusions: Many patients have not required WBRT during their clinical course and so were not at risk of neurocognitive toxicity of WBRT. Our study suggests that postoperative SRS/SRT may be a viable option for patients who have undergone resection of brain metastases. WBRT can be reserved as salvage with acceptable neurological deficit-free survival rates.
Author Disclosure: L. Do, None; R.D. Pezner, None; E. Radany, None; A. Liu, None; C. Staud, None; B. Badie, None.
2081
Clinical Experience With Radiation Therapy in the Management of Neurofibromatosis-Associated Central Nervous System Tumors
S. Wentworth, T. L. Ellis, S. Glazier, K. P. McMullen, V. W. Stieber, S. B. Tatter, E. G. Shaw Wake Forest University, Winston-Salem, NC Purpose/Objective(s): Patients with neurofibromatosis (NF) frequently develop tumors of the central nervous system (CNS). Radiation therapy (RT) is sometimes used in treating these lesions. To better define the efficacy of RT in controlling NF-associated CNS tumors, we reviewed our 20 year experience. Patients/Methods: Seventy-four lesions in 16 patients with NF were treated with RT from 1986–2006. One third of patients had NF1, two thirds NF2. Median follow up was 36 months. Progression was defined as tumor growth or recurrence in an irradiated lesion on serial imaging. Progression free survival was measured from date of treatment to date of last imaging follow up. The actuarial rates of progression free survival were calculated according to the Kaplan Meier method. Results: On average, 5 lesions were treated per patient. The most common indication for treatment was growth on serial imaging. Median age at time of treatment was 24.1 years (range: 4.3–57.1). The treated lesions included acoustic neuromas (9%), ependymomas (7%), low grade gliomas (12%), meningiomas (62%), and non-acoustic schwanommas/neurofibromas (8%). Most patients (62%) received stereotactic radiosurgery. The others received fractionated external beam RT. Overall survival at 5 years for all patients was 94%. Five year progression free survival was 100% (acoustic neuromas), 75% (ependymomas), 100% (low grade gliomas), 86% (meningiomas) and 100% (non-acoustic schwannomas). Most patients with acoustic neuromas were deaf prior to treatment. In those patients with pre-treatment useful hearing, the hearing preservation rate was 0% (Fig.). Conclusions: This is the largest published experience on the results of RT in NF patients with CNS tumors. The progression free survival rates herein are similar or superior to those published for non-NF patients treated with RT. RT should be considered in NF patients with CNS tumors.
Proceedings of the 49th Annual ASTRO Meeting
S249
Author Disclosure: S. Wentworth, None; T.L. Ellis, None; S. Glazier, None; K.P. McMullen, None; V.W. Stieber, None; S.B. Tatter, None; E.G. Shaw, None.
2082
Reliability of Bony Anatomy in Image-Guided Stereotactic Radiotherapy of Brain Metastases
M. P. Flentje, K. Baier, I. Guenther, J. Wilbert, A. Richter, O. Sauer, M. Guckenberger University of Wurzburg, Wurzburg, Germany Purpose/Objective(s): To evaluated whether the position of brain metastases remained stable between planning and treatment in cranial stereotactic radiotherapy (SRT). Materials/Methods: 18 patients with 20 brain metastases were treated with single fraction (n = 17) or hypofractionated (n = 3) image-guided SRT for brain metastases. Patients were immobilized in stereotactic Scotch-cast masks (SC; n = 12) or thermoplastic head masks (TP; n = 8). Prior to treatment a cone-beam CT (CBCT) was acquired and patient set-up was evaluated by automatic image registration with the planning CT; the bony anatomy of the skull was basis for this image registration. Additionally, a conventional CT study was acquired for all patients using an in-room CT scanner: the amount of iv contrast given to the patient and the slice thickness were identical to treatment planning, the table feed was 1 mm. Patient set-up was evaluated based on the position of the brain metastases. Results of bone-match and soft-tissue match for verification of patient set-up were compared. Results: Median time interval between planning and treatment was eight days. Based on automatic bone registration of CBCT and planning CT the 3D positioning errors were 3 mm ± 1.7 mm and 4.6 mm ± 2.1 mm for patients immobilized in SC and TP masks (p = 0.09), respectively. Tumor size was not significantly different between planning and treatment. The 3D set-up error was 4.0 mm ± 2.1 mm and 3.5 mm ± 2.2 mm based on the bony anatomy and the lesion itself, respectively. A highly significant correlation between automatic bone match and soft-tissue registration was seen in all three directions (r $ 0.88). The distance between the iscocentre based on bone match and soft-tissue registration was 1.7 mm ± 0.7 mm, maximum 2.8 mm. Treatment of intracranial pressure with steroids did not influence the position of the lesion relative to the bony anatomy. Conclusions: With a time interval of about one week between planning and treatment the bony anatomy of the skull proved as an excellent surrogate for the target position in image-guided SRT. Own data and data from the literature using 3D-3D image registration for verification of patient set-up suggest that stereotactic head masks are less reproducible for patient positioning than reported with 2D-2D image registration. This further emphasizes the benefit of image-guidance in (fractionated) SRT.
Study 2D-2D image registration for verification of set-up Rosenthal 1995 Hamilton 1996 Theodorou 1998 Alheit 2001 Kalapurakal 2001 Karger 2001 Sweeney 2001 Kumar 2005 Georg 2006 3D-3D image registration for verification of set-up Baumert 2005 Boda-Heggemann 2006 Own study
SRT positioning system
Imaging modality
Positioning error
Dental fixation & thermoplastic mask Scotch cast mask Inhouse frame Brain Lab Mask Laitinen stereotactic localizer & head holder Scotch cast mask Vogele Bale Hohner head holder Gill-Thomas-Cosman Brain Lab Mask
Orthogonal radiographs & Portal imaging Portal imaging Orthogonal radiographs Portal imaging Portal imaging Orthogonal radiographs Portal imaging Portal imaging Portal imaging
2.3 mm ± 1.6 mm # 1.8 mm # \1 mm * \2 mm * #1 mm * 1.2 mm * 1.9 mm ± 1.2 mm # 1.8 mm ± 0.8 mm # 1.3 mm ± 0.9 mm #
Stereotactic mask Scotch cast mask Scotch cast mask
CT Cone-beam CT Cone-beam CT
3.7 mm ± 0.8 mm # 3.1 mm ± 1.5 mm # 3.0 mm ± 1.7 mm #
# 3D error vector (mean ± SD); * largest 2D error in any direction (SD).
Author Disclosure: M.P. Flentje, None; K. Baier, None; I. Guenther, None; J. Wilbert, None; A. Richter, None; O. Sauer, None; M. Guckenberger, None.