Faculty Bibliography

OBJECT: To evaluate outcome predictors after stereotactic radiosurgery (SRS) in patients with trigeminal schwannomas, the authors compared tumor control, functional preservation, and complications with tumor grade, tumor volume, patient age, and tumor imaging characteristics. METHODS: The records of 33 consecutive patients with trigeminal schwannoma treated via Gamma Knife surgery were retrospectively reviewed. The median patient age was 49.5 years (range 15.1-82.5 years). Eleven patients had undergone prior tumor resection. Two patients had neurofibromatosis Type 2. Lesions were classified as root type (6 tumors), ganglion type (17 tumors), and dumbbell type (10 tumors) based on their location. The median radiosurgery target volume was 4.2 cm3 (range 0.5-18.0 cm3), and the median dose to the tumor margin was 15.0 Gy (range 12-20 Gy). RESULTS: At an average of 6 years (range 7.2-147.9 months), the rate of progression-free survival (PFS) at 1, 5, and 10 years after SRS was 97.0, 82.0, and 82.0%, respectively. Factors associated with improved PFS included female sex, smaller tumor volume, and a root or ganglion tumor type. Neurological symptoms or signs improved in 11 (33.3%) of 33 patients and were unchanged in 19 (57.6%). Three patients (9.1%) had symptomatic disease progression. Patients who had not undergone a prior tumor resection were significantly more likely to show improvement in neurological symptoms or signs. CONCLUSIONS: Stereotactic radiosurgery is an effective and minimally invasive management option in patients with residual or newly diagnosed trigeminal schwannomas. Predictors of a better treatment response included female sex, smaller tumor volume, root or ganglion tumor type, and the application of SRS as the primary treatment.

OBJECT: In this study the authors evaluated the role of stereotactic radiosurgery (SRS) in the management of progressive or newly diagnosed small-volume oligodendrogliomas. Tumor control, survival, and complications were assessed in patients with oligodendroglioma who underwent Gamma Knife radiosurgery as a primary or adjuvant procedure. METHODS: The authors retrospectively reviewed 30 patients with oligodendroglioma (12 Grade II and 18 Grade III) who underwent SRS between 1992 and June 2006 at the University of Pittsburgh. The median patient age was 43.2 years (range 10.8-75.4 years). Twenty-four patients had previously undergone resection of the tumor, whereas tumors in 6 were diagnosed based on biopsy findings. The SRS was performed in 25 patients who had imaging-defined tumor progression despite prior fractionated radiation (22 patients) and/or chemotherapy (20 patients). The median target volume was 15.4 cm(3) (range 0.07-48.7 cm(3)) and the median margin dose was 14.5 Gy (range 11-20 Gy). RESULTS: At an average of 39.2 months of follow-up (range 12-133 months), 17 patients were dead and 13 were living. The overall survival rates from diagnosis to 5 and 10 years were 90.9 and 68.2%, respectively, for Grade II and 52.1% at 5 years and 26.1% at 10 years for Grade III. Factors associated with an improved progression-free survival included lower tumor grade and smaller tumor volume. In 13 patients who had loss of heterozygosity testing, patients with 1p19q loss of heterozygosity had a significantly improved survival after diagnosis (p = 0.04). CONCLUSIONS: The SRS modality is a minimally invasive additional option for patients with residual or recurrent oligodendrogliomas. It may also be considered as an alternative to initial resection in small-volume tumors located in the cortical brain region.

To assess outcomes after stereotactic radiosurgery (SRS) for newly diagnosed or recurrent pilocytic astrocytomas in pediatric patients. Fifty patients (28 male and 22 females) with juvenile pilocytic astrocytomas (JPA) underwent Gamma knife SRS between 1987 and 2006. The median patient age was 10.5 years (range, 4.2-17.9 years). Three patients had failed prior fractionated radiation therapy (RT) and two had failed RT and chemotherapy. The median radiosurgery target volume was 2.1 cc (range, 0.17-14.4 cc) and the median margin dose was 14.5 Gy (range, 11-22.5 Gy). At a median follow-up of 55.5 months (range 6.0-190 months), one patient died and 49 were alive. The progression free survival after SRS (including tumor growth and cyst enlargement) for the entire series was 91.7, 82.8 and 70.8% at 1, 3 and 5 years, respectively. Stereotactic radiosurgery for pediatric pilocytic astrocytomas should be considered when resection is not feasible, or if there is an early recurrence. The best response was observed in small volume residual solid tumors.

AIMS: We analyzed the efficiency of the Leksell Gamma Knife Perfexion (LGK PFX) in the treatment of multiple metastases and benign tumors. We also compared treatment planning conformity between LGK PFX and LGK 4C for benign tumors. METHOD: Over a 6-week interval, 37 patients (21 with multiple brain metastases and 16 with benign tumors) underwent radiosurgery using LGK PFX at the University of Pittsburgh. We created dose plans for all patients using Leksell Gamma Plan for LGK PFX and LGK 4C. The same doses were prescribed for both LGK PFX and LGK 4C. RESULTS: No significant difference was observed between LGK 4C and LGK PFX for total beam-on time. The median reduction in setup time on the LGK PFX was 53 min per patient (range 19-125 min) for multiple metastases. The median reduction in setup time on the LGK PFX for benign tumors was 16 min per patient (range 5-53 min). There was no significant difference in the dose conformality between LGK 4C and LGK PFX. CONCLUSIONS: This study demonstrated that in addition to its enhanced cranial reach, LGK PFX provided a significant improvement in efficiency for patients with multiple brain metastases. For benign tumor radiosurgery LGK PFX provided improvement in efficiency without a significant difference in conformality.

BACKGROUND: We evaluated the role of Gamma Knife SRS in the multidisciplinary management of metastatic cancer to the pituitary gland. METHODS: We retrospectively reviewed records of 18 consecutive pituitary metastasis patients who underwent Gamma Knife SRS during a 21-year experience. The median patient age was 57.6 years (range, 27.0-81.1 years). There were 5 patients who had initial surgical resection of their pituitary metastasis, 5 who had fractionated radiation, and 7 who had CT before SRS. The median radiosurgery target volume was 3.5 mL (range, 0.2-18.0 mL), and the median marginal dose was 13.0 Gy (range, 9-18 Gy). RESULTS: The overall survival after SRS at 3, 6, and 12 months, respectively, was 66%, 36%, and 18%. The median survival after SRS was 5.2 months. The progression-free survival after SRS was 100% and 66.7% at 6 and 12 months, respectively. The only factor associated with an improved overall survival was younger age at presentation. Diabetes insipidus improved in 3 (42.9%) of 7 patients. Neurological symptoms or signs improved in 4 (50.0%) of 8 patients. Three (16.7%) patients developed new neurological deficits due to tumor progression despite SRS. CONCLUSION: Development of a pituitary metastasis is an ominous finding in the context of systemic cancer. Stereotactic radiosurgery is an effective palliative approach for most patients with pituitary metastasis.

OBJECT: The aim in this study was to determine the outcomes of boost stereotactic radiosurgery, specifically Gamma Knife surgery (GKS), for recurrent primitive neuroectodermal tumors (PNETs) in children in whom initial multimodality management had failed. METHODS: The authors performed a retrospective analysis of 7 patients who underwent a total of 15 GKS procedures for locally recurrent or metastatic PNETs. Nine procedures were directed at the primary site, whereas 6 were directed at distant brain sites. All patients received multimodality therapy, including resection, fractionated radiotherapy, and chemotherapy. The mean interval from diagnosis to first stereotactic radiosurgery was 25.8 months (range 11-35 months). The mean tumor volume was 3.9 cm(3) (range 1.1-13.1 cm(3)), and an average marginal dose of 14.5 Gy (range 9-20 Gy) was administered. RESULTS: Following salvage GKS, 2 patients had early disease progression (median survival of 5 months after GKS). Five patients had late disease progression (complete response in 3, partial response in 1, and stable disease in 1) and a median survival of 30 months after GKS. Four of the 5 patients who had late progression underwent repeat GKS for marginal recurrence. No adverse radiation effects were observed in these 7 patients. CONCLUSIONS: The GKS modality was a well-tolerated and useful boost strategy in pediatric patients with PNET and a poor prognosis in whom initial multimodality management had failed. However, local or distant disease progression or diffuse leptomeningeal spread ultimately proved fatal to these patients.

PURPOSE: Intraventricular meningiomas are relatively rare tumors that may benefit from stereotactic radiosurgery as a minimally invasive treatment strategy. We report our experience using gamma knife radiosurgery (GKR) for intraventricular meningiomas. METHODS: Over a 16-year period, we identified 9 patients with intraventricular meningiomas who were eligible for GKR out of a total management experience of 1,045 patients. The mean patient age was 51 years (range, 14 to 81). Three had radiosurgery for recurrent tumors after prior resection, and GKR was used as an adjunctive after subtotal resection in 1 patient. In the other 5 patients, GKR was used as primary management. Two had a diagnosis of meningioma confirmed by biopsy. The median tumor volume at GKR was 3.9 cc (range, 0.8-11.8). A median margin dose of 16.0 Gy (range, 14.0-22.5) was delivered to the tumor margin. RESULTS: The average follow-up was 64 months. None of the patients developed hydrocephalus or treatment-related morbidity. The progression-free periods after radiosurgery varied from 7 to 160 months (mean, 60). Four tumors regressed and 2 remained unchanged. Three patients showed delayed tumor progression. Meningioma growth control was obtained in 7 out of 9 patients, but 1 patient required two radiosurgical procedures. CONCLUSIONS: Gamma knife radiosurgery may be an additional minimally invasive management option for small intraventricular meningiomas in patients who either fail or are unsuitable for resection.

OBJECTIVE: Patients who have a schwannoma of the facial nerve (facial schwannoma, facial neuroma) can be managed with observation, surgical resection, stereotactic radiosurgery, or fractionated radiotherapy. Attempted complete resection is associated with facial weakness. The role of radiosurgery in these patients remains to be defined. METHODS: We reviewed the clinical and imaging outcomes in patients who underwent gamma knife radiosurgery for a facial schwannoma. RESULTS: Six patients had radiosurgery and were followed for a mean and median of 46.6 and 61.5 months, respectively (21-85 months). Three had a previous resection, and in 3 the diagnosis was made based on clinical and imaging criteria. All patients had facial nerve symptoms (5 had weakness and 1 had muscle twitching). House-Brackmann grades before radiosurgery were as follows: 1 (n = 1), 2 (n = 3), 3 (n = 1), and 6 (n = 1). The radiosurgery margin dose was 12 or 12.5 Gy. On later imaging, 3 tumors had regressed (with the longest follow-up duration) and 3 were unchanged. All patients had preservation of their preradiosurgery facial function. No other adverse effects were noted and all patients maintained their preradiosurgery level of hearing. CONCLUSION: Over a mean of almost 4 years of follow-up, radiosurgery was shown to be a safe and effective management for residual and newly diagnosed facial schwannomas.

We evaluated 20 pineal parenchymal tumor patients who underwent radiosurgery at our institution over a 20-year period. Thirteen patients had pineocytoma, 5 patients had pineoblastoma and 2 patients had mixed pineal parenchymal tumors. The median radiosurgery prescription dose to the tumor margin was 15.0 (12-20) Gy. At an average of 54.1 (range, 7.7-149.2) months, 6 patients had died and 14 patients were living. The overall survival after radiosurgery was 95.0, 68.6, and 51.4% at 1, 5 and 10 years, respectively. Patients with pineocytomas had 1-, 3- and 5-year overall survivals of 100, 92.3 and 92.3%, respectively. In 19 patients who were evaluated with imaging, 5 (26%) demonstrated complete regression, 9 (47%) had partial regression, 2 (11%) had stable tumors and 2 (11%) showed local in-field progression. The progression-free survival after stereotactic radiosurgery for all type of pineal parenchymal tumors was 100, 89.2 and 89.2% at 1, 3, 5 years after radiosurgery, respectively. Stereotactic radiosurgery is an effective and safe alternative to the surgical resection of pineocytomas as well as part of multimodal therapy for more aggressive pineal parenchymal tumors.

PURPOSE: Involvement of the cavernous sinus by direct invasion from skull base cancer or from metastatic spread of cancers is a challenging problem. We evaluated the role of stereotactic radiosurgery (SRS) in the treatment of patients who developed cavernous sinus metastases or direct invasion. METHODS AND MATERIALS: We retrospectively reviewed the data from 37 patients who had cavernous sinus metastases or had cavernous sinus invasion from adjacent skull base cancers and who underwent SRS between 1992 and 2006 at the University of Pittsburgh Medical Center. The median patient age was 57.8 years. Previous adjuvant management included fractionated radiotherapy in 8, chemotherapy in 16, and both radiotherapy and chemotherapy in 5. The primary sites of metastases or invasion were nasopharyngeal carcinoma (n = 7), parotid gland carcinoma (n = 7), and metastases from systemic cancer (n = 23). The median target volume was 6.3 cm(3) (range, 0.3-33.6), and the median margin dose was 14 Gy (range, 12-20). RESULTS: At a mean of 12.9 months (range, 0.8-63.9), 32 patients had died and 5 were living. The overall survival rate after SRS was 36.6% and 19.4% at 1 and 2 years, respectively. Progression-free survival was related to a greater marginal dose. After SRS, 12 (35.3%) of 34 patients with neurologic symptoms exhibited improvement. SRS early after diagnosis was significantly associated with improvement of cranial nerve dysfunction. CONCLUSION: SRS is a minimally invasive palliative option for patients whose cancer has invaded the cavernous sinus. The benefits for cranial nerve deficits are best when SRS is performed early.