Article

Radiosurgical Induced Neoplasia: A Seldom Seen Complication

Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia, USA.
World Neurosurgery (Impact Factor: 2.42). 06/2010; 73(6):644-5. DOI: 10.1016/j.wneu.2010.05.017
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    ABSTRACT: Purpose of the studyIn order to investigate the role of radiosurgery and stereotactic radiotherapy in the management of vestibular schwannomas, we have reviewed our own prospective cohort and the main series of the modern literature.Patients and methodsBetween July 14th 1992 and June 1st 2011, 2991 vestibular schwannomas were operated on the Stereotactic and Functional Neurosurgery Department of Timone University Hospital. All the patients have been evaluated prospectively, with a follow up longer than 3 years for 2336 patients, excluding patients suffering from type 2 neurofibromatosis (148 patients). In 7% of the patients, the vestibular schwannoma had previously been resected. According to Koos classification, in 17.6% of the patients, vestibular schwannomas were stage I, 51.8% stage II, 27% stage III and 3.6% stage IV. The mean tumour volume was 2.63 cm3. According to Garner Robertson classification, the hearing was still functional at the time of radiosurgery in 46% and subnormal in 20.9% of the patients.ResultsLong term tumour control was achieved in 97.5% of the patients. A transient facial palsy was observed in 0.5% of the cases. The rate of trigeminal injury was 0.5%. Useful hearing was preserved at 3 years in 78%. This rate reached 95% in patients with no past history of sudden hearing loss. Other predictors of functional hearing preservation are the young age, the small size of the lesion and a dose to the modiulus of the cochlea lower than 4 Gy. We observed no radio-induced tumour. Only large, Koos IV vestibular schwannomas are contraindicated for upfront radiosurgery. In these patients, we propose a combined approach with a deliberately partial microsurgical removal, followed by a radiosurgery of the residue.Conclusion This cohort is unique by the size of the population and the length of the follow up and results demonstrate the efficacy of radiosurgery and its safety, especially its high rate of hearing preservation.
    Cancer/Radiothérapie 06/2012; 16:S70–S78. DOI:10.1016/j.canrad.2012.01.006
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    ABSTRACT: OBJECT: Gamma Knife radiosurgery (GKRS) is a minimally invasive technique employed in the treatment of intracranial arteriovenous malformations (AVM's). Patients experience a low incidence of complications following treatment. As the long-term follow-up data became available, some late adverse effects have been reported. However, the exact incidence of radiosurgically induced neoplasia is not known. METHODS: At UVA, imaging and clinical outcomes of 1309 patients with intracranial AVM's treated with GKRS have been reviewed. AVM patients underwent magnetic resonance imaging (MRI's) every 6 months for 2 years and then annually following GKRS. When the nidi were no longer visible on MRI, angiography was performed to verify the obliteration of AVM's. Patients were thereafter recommended to continue MRI's every 3-5 years to detect any long-term complications. A subset of 812, 358, and 78 patients had neuro-imaging and clinical follow-up of at least 3, 10, and 15 years respectively. RESULTS: The authors report the occurrence of 3 cases of radiosurgically induced neoplasia. More than 10 years after GKRS, 2 patients were found to have an incidental, uniformly enhancing, dural based mass lesion near the site of the AVM with radiological characteristics of a meningioma. As the lesions have shown no evidence of mass effect, they are being followed with serial neuro-imaging. A third patient was found to have neurological decline from a tumor in immediate proximity to an AVM previously treated with proton beam radiosurgery and GKRS. The patient underwent resection demonstrating a high grade glioma. The 3, 10, and 15-year incidence of a radiation-induced tumor is 0% (0/812), 0.3% (1/358), and 2.6% (2/78) respectively. The cumulative rate of radiosurgically induced tumors in those with a minimum of 10 year follow up is 3 in 4692 person-years or 64 in 100,000 person-years. Thus, patients had a 0.64% chance of developing a radiation induced tumor within 10 or more years following GKRS. If we calculate rates based on a subset of 78 patients with neuro-imaging and clinical follow-up of at least 15 years, the cumulative rate was 3.4%. These are the 2(nd), 3(rd), and 5(th) reported cases of radiation induced tumors following GKRS for an AVM. CONCLUSIONS: Although radiosurgery is generally considered a safe modality in the treatment of AVM's, radiation induced neoplasia is a rare but serious adverse event. The possibility of GKRS induced tumors underscores the necessity of long-term follow-up in AVM patients receiving radiosurgery.
    World Neurosurgery 02/2013; 82(3-4). DOI:10.1016/j.wneu.2013.02.008
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    ABSTRACT: Object Pituitary adenomas are fairly common intracranial neoplasms, and nonfunctioning ones constitute a large subgroup of these adenomas. Complete resection is often difficult and may pose undue risk to neurological and endocrine function. Stereotactic radiosurgery has come to play an important role in the management of patients with nonfunctioning pituitary adenomas. This study examines the outcomes after radiosurgery in a large, multicenter patient population. Methods Under the auspices of the North American Gamma Knife Consortium, 9 Gamma Knife surgery (GKS) centers retrospectively combined their outcome data obtained in 512 patients with nonfunctional pituitary adenomas. Prior resection was performed in 479 patients (93.6%) and prior fractionated external-beam radiotherapy was performed in 34 patients (6.6%). The median age at the time of radiosurgery was 53 years. Fifty-eight percent of patients had some degree of hypopituitarism prior to radiosurgery. Patients received a median dose of 16 Gy to the tumor margin. The median follow-up was 36 months (range 1-223 months). Results Overall tumor control was achieved in 93.4% of patients at last follow-up; actuarial tumor control was 98%, 95%, 91%, and 85% at 3, 5, 8, and 10 years postradiosurgery, respectively. Smaller adenoma volume (OR 1.08 [95% CI 1.02-1.13], p = 0.006) and absence of suprasellar extension (OR 2.10 [95% CI 0.96-4.61], p = 0.064) were associated with progression-free tumor survival. New or worsened hypopituitarism after radiosurgery was noted in 21% of patients, with thyroid and cortisol deficiencies reported as the most common postradiosurgery endocrinopathies. History of prior radiation therapy and greater tumor margin doses were predictive of new or worsening endocrinopathy after GKS. New or progressive cranial nerve deficits were noted in 9% of patients; 6.6% had worsening or new onset optic nerve dysfunction. In multivariate analysis, decreasing age, increasing volume, history of prior radiation therapy, and history of prior pituitary axis deficiency were predictive of new or worsening cranial nerve dysfunction. No patient died as a result of tumor progression. Favorable outcomes of tumor control and neurological preservation were reflected in a 4-point radiosurgical pituitary score. Conclusions Gamma Knife surgery is an effective and well-tolerated management strategy for the vast majority of patients with recurrent or residual nonfunctional pituitary adenomas. Delayed hypopituitarism is the most common complication after radiosurgery. Neurological and cranial nerve function were preserved in more than 90% of patients after radiosurgery. The radiosurgical pituitary score may predict outcomes for future patients who undergo GKS for a nonfunctioning adenoma.
    Journal of Neurosurgery 04/2013; 119(2). DOI:10.3171/2013.3.JNS12766