Radiosurgical Induced Neoplasia: A Seldom Seen Complication
Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia, USA.World Neurosurgery (Impact Factor: 2.88). 06/2010; 73(6):644-5. DOI: 10.1016/j.wneu.2010.05.017
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ABSTRACT: The goal of this study was to determine factors associated with endocrine normalization after radiosurgery is performed in patients with hormone-producing pituitary adenomas. Between 1990 and 1999, 43 patients with hormone-producing pituitary adenomas underwent radiosurgery: 26 patients with growth hormone (GH)-producing tumors, nine with adrenocorticotrophic hormone-producing tumors, seven with tumors that produced prolactin (PRL) alone, and one with a tumor that secreted both GH and PRL. The median patient age was 42 years. Thirty-seven patients (86%) had undergone surgery earlier and in 30 (70%) there was tumor extension into the cavernous sinus. The product-limit method was used to calculate endocrine normalization while patients were not receiving any hormone-suppressive medication. The median follow-up period after radiosurgery was 36 months (range 12-108 months). In 20 patients (47%) there was normalization of hormone secretion at a median of 14 months (range 2-44 months) after radiosurgery; no correlation was found between tumor type and cure. Actuarial cure rates were 20, 32, and 61% at 1, 2, and 4 years posttreatment. Multivariate analysis demonstrated that the absence of hormone-suppressive medications at the time of radiosurgery (relative risk 8.9, 95% confidence interval [CI] 1.2-68.7, p = 0.04) and maximum radiation doses greater than 40 Gy (relative risk 3.9, 95% CI 1.3-11.7, p = 0.02) correlated with an endocrine cure. A new anterior pituitary deficiency developed in seven patients (16%), temporal lobe necrosis was identified in two patients, an asymptomatic internal carotid artery stenosis was detected in two patients, and unilateral blindness occurred in one patient. Radiosurgery provides an endocrine cure for many patients with persistent or recurrent hormone-producing pituitary adenomas. Further study is needed to determine whether pituitary hormone-suppressive medications have a radioprotective effect.
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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.
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ABSTRACT: Objective: Gamma Knife radiosurgery (GKRS) is a minimally invasive technique employed in the treatment of intracranial arteriovenous malformations (AVMs). Patients experience a low incidence of complications following treatment. As 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 University of Virginia, imaging and clinical outcomes of 1309 patients with intracranial AVMs treated with GKRS have been reviewed. AVM patients underwent magnetic resonance imaging (MRI) every 6 months for 2 years and then annually following GKRS. When the nidi were no longer visible on magnetic resonance imaging, angiography was performed to verify the obliteration of AVMs. Patients were thereafter recommended to continue MRIs every 3-5 years to detect any long-term complications. A subset of 812, 358, and 78 patients had neuroimaging 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 radiologic characteristics of a meningioma. As the lesions have shown no evidence of mass effect, they are being followed with serial neuroimaging. A third patient was found to have neurologic 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 years following GKRS. If we calculate rates based on a subset of 78 patients with neuroimaging and clinical follow-up of ≤15 years, the cumulative rate was 3.4%. These are the second, third, and fifth reported cases of radiation-induced tumors following GKRS for an AVM. Conclusions: Although radiosurgery is generally considered a safe modality in the treatment of AVMs, 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.
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