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1997 Patient/Provider ConferenceFocus on Stereotactic Radiosurgery
AbstractsFriday, May 2, 1997, Bethesda, Maryland
For patient experiences, see Caution
Urged on Stereotactic Radiosurgery
Agenda:
Introduction
Stereotactic Radiation for CNS Tumors in VHL
Surgical Management of Posterior Fossa Hemangioblastoma in VHL
The Role of Stereotactic Radiosurgery in the Management of Hemangioblastoma
Other adjuvant management strategies must be considered for patients with hemangioblastomas which cannot be resected safely by surgery, recur despite prior surgery, or are initially incompletely resected. This is especially critical in patients with multiple hemangioblastoma in the context of von Hippel-Lindau (VHL) syndrome. Surgical resection of multiple lesions is frequently impossible.
Prior experience with the usage of fractionated radiation therapy of the brain indicates that higher doses are necessary to achieve or enhance local tumor control. Stereotactic radiosurgery refers to single treatment session focal irradiation of a relatively small volume neoplasm. The twin goals are prevention of further tumor growth (sometimes associated with significant tumor regression), and preservation of normal brain function. This is especially critical in the management of hemangioblastomas, which are generally thought to be slow growing, benign histological neoplasms.
Stereotactic radiosurgery can be delivered by rotation of multiple non-co-planar arcs using an existing linac accelerator (modified from its use for fractionated radiation therapy of the brain) or by using especially designed technology which employs 201 beams of Cobalt-60 irradiation specifically designed for focal irradiation of brain tumors (gamma knife). More than 30 years of experience with the gamma knife has now been reviewed. As of June 1996, 75 units worldwide were in operation, and 43,706 total tumors had been treated. Of these, 18,954 represented benign tumors; 279 patients had hemangioblastomas.
The results of the treatment by stereotactic radiosurgery of hemangioblastomas in 38 patients was reported by three sites in 1996. The best results were achieved in patients with smaller volume lesions treated with a minimum tumor dose in a single treatment session of 16 Gy or greater. In this series of 38 patients, 78% of patients remain neurologically stable or clinically improved. No patient had significant permanent complications related to stereotactic radiosurgery. Two year actuarial overall survival in this series was 88 +/- 15%.
At the University of Pittsburgh during a ten year interval, 14 patients (out of a total experience of 14,000 patients with brain tumors) had hemangioblastomas. Tumor control rate was high for patients with small volume tumors, but was less optimal in patients with recurrent cystic or large tumors. Such patients often require surgical resection. Residual portions of the tumor can be treated afterwards by radiosurgery.
An increasing experience with stereotactic radiosurgery for cerebellar and brainstem hemangioblastomas has occurred worldwide. Radiosurgery provides a significant benefit for hemangioblastoma patients, especially in the context of VHL disease.
Hemangioblastoma and Radiosurgery
Excerpts from slides prepared by Dr. Adler and Dr. Steven D. Chang
Patients with von Hippel-Lindau disease (VHL) develop multiple, recurrent hemangioblastomas over a lifetime. Multiple operations often produce additional neurological problems, are disruptive to patients' lives and expensive.
Typically VHL patients are known to have the disease and many or most tumors are found on screening imaging studies before becoming symptomatic. As a result of prior tumors and surgery especially those involving the brainstem many patients have neurologic deficits and surgical resection poses greater risk.
At Stamford our experience has been that there is a broad spectrum of risk involved in microsurgical resection depending on tumor location and size. Resection of a solitary cerebellar lesion is generally association with little risk of permanent neurologic deficits. However, the opposite is true of many brainstem and spinal cord tumors.
VHL patients tend to be good candidates for radiosurgery. Hemangioblastomas found during screening are often small and relatively spherical. Patients may have multiple simultaneous tumors, often in surgically less accessible locations.
Radiosurgical ablation is an outpatient procedure, does not involve open surgery, and carries minimal risk with small tumors. Multiple lesions may be treated simultaneously. The ideal radiosurgical candidate in our experience is one with a previously established diagnosis of VHL, a relatively small lesions (less than 10 cc in volume), with no or minimal mass effect [no symptoms due to pressure], and a "patient patient," as results do not come rapidly.
In our experience, tumors which should NOT be treated with stereotactic radiosurgery (SRS) are large lesions (volume greater than 20 cc), tumors causing clinically significant mass effect, or a large number of simultaneous lesions.
There are some drawbacks to radiosurgery. You do not get the tumor out and cannot study it under the microscope, precluding histological diagnosis. It does not instantly eliminate the mass effect. It takes quite a while before cystic tumors stop reforming cysts, which may mean a series of interventions to manage the cystic component. And follow-up scans don't "look" as good. There is some shadow in the way in future studies.
It is clear that with today's imaging technology we can see more tiny tumors than will grow and become problematic. We are unsure whether it is necessary to treat all tumors. The ones we do treat are ones which are shown to be enlarging, cystic tumors without a mass effect, and the largest and/or symptomatic tumors. Very small tumors which do not appear to be enlarging might be left without treatment for a while and monitored for future growth.In our series 30 tumors in 14 patients were treated with radiosurgery. The mean age of the patients was 43 (range was 31 to 80), 11 males, 3 females, with a mean Karnofsky index of 90 (range 60-100). All but 2 patients had prior open surgery. Mean number of prior resections was 2.2 (range 1-5). Only one patient had previous external beam radiotherapy. Two complications were experienced: one infected bone graft and one had hydrocephalus requiring a shunt.
The 30 tumors treated had a maximal diameter of 14.6 mm (range 5-50mm). At the time of treatment, 11 patients had other radiologically apparent lesions ranging from 2-7 mm. Radiosurgical treatment dose: mean 26.1 Gy (range 20-40 Gy). One tumor was re-treated after 9 months with an additional 40 Gy, receiving a total of 75 Gy. Isocenters: mean 1.3 (range 1-4). Secondary collimators: mean 12.3 mm (range 7.5-22.5 mm.)
13 of the 14 patients remain alive and asymptomatic from the treated lesions. One patient required re-treatment of a cystic lesions which persisted after initial treatment. It disappeared after re-treatment. One patient died 19 months after radiosurgery from progression of 3 untreated hemangioblastomas. No patient had documented radiologic progression of a treated lesion.
Two patients suffered acute nausea. Two patients developed radionecrosis. One required a VP shunt and steroids, another developed transient ataxia which improved with steroids. Both were treated with multiple isocenters and a high dose in the region of overlap.
Follow-up over an average of 38 months showed that 8 patients had radiographic and/or symptomatic progress of untreated tumors, but none of the treated hemangioblastomas resulted in progressive symptoms. We feel there is modest risk with SRS in people with VHL and that radiosurgery is an effective treatment for small, unresectable, recurrent or multifocal hemangioblastomas.
References:
Surgical Management of Hemangioblastoma
Introduction and methods. Eighty operations for hemangioblastoma were identified over a twenty-year period through a computerized pathology database. We retrospectively reviewed available medical records and selected radiographs of these patients.
Results. There were forty men and thirty-two women. Twenty-one patients had other sequelae diagnostic of von Hippel-Lindau disease (VHL). These patients had twenty-eight operations. There were fifty-four operations performed on fifty-three patients with sporadic hemangioblastoma. Sixty-four of the operations were for posterior-fossa lesions, and fifteen for spinal lesions. Six lesions involved the brain stem; four of these at the foramen magnum. In three of the spinal operations tumor occurred on a nerve root. The mean age at operation was 33 yr for patients with VHL and 43 yr for patients with sporadic hemangioblastoma. The difference in age was statistically significant (at P=0.001 by a log-rank test).
Thirty-one of the operations in twenty-five patients were performed by one or both of the authors. Forty-two lesions were treated in these patients and a total of 199 patient-years of follow-up is available. Twenty-six patients had gross total resections and four had partial resections or biopsies. Three lesions were irradiated after surgery and one lesion at a site distant from the operation was treated by irradiation alone. There were two permanent complications both among the give patients whose lesions involved the brainstem. There was one transient cerebrospinal fluid fistula. Ten year progression free survival after surgery was eighty-three percent for patients with VHL and one hundred percent for patients without VHL.
Spinal hemangioblastoma. Eight patients had von Hippel-Lindau Disease (VHL: 1 to 8 spinal lesions per patient) and seven had solitary sporadic spinal hemangioblastoma. The mean age was 32 yr (range 17-47 yr) for patients with VHL and 37 yr (range 16-63 yr) for sporadic cases. These patients harbored a total of 36 spinal lesions, of which 19 were resected (13 cervical or cervicomedullary, 5 thoracic, 1 lumbar). Gross total resection of the approached lesions was achieved in all but one instance. There were no recurrences of resected lesions or progression of nonresected lesions that required treatment during 56 patient-years of follow-up. One patient who underwent biopsy had worsening of paraparesis after operation, and a second patient had delayed cervical instability that required fusion. Three VHL patients died of metastatic renal cell carcinoma; all other patients were alive at last follow-up.
Discussion and conclusions. Many hemangioblastomas do not require resection. When resection is required for progressive neurologic deficit or tumor enlargement, very low rates of morbidity and a low likelihood of recurrence can be expected for both spinal and posterior-fossa hemangioblastoma, particularly for lesions not involving the brainstem.
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