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PubMed2000

A geometrically based method for automated radiosurgery planning.

PURPOSE: A geometrically based method of multiple isocenter linear accelerator radiosurgery treatment planning optimization was developed, based on a target's solid shape. METHODS AND MATERIALS: Our method uses an edge detection process to determine the optimal sphere packing arrangement with which to cover the planning target. The sphere packing arrangement is converted into a radiosurgery treatment plan by substituting the isocenter locations and collimator sizes for the spheres. RESULTS: This method is demonstrated on a set of 5 irregularly shaped phantom targets, as well as a set of 10 clinical example cases ranging from simple to very complex in planning difficulty. Using a prototype implementation of the method and standard dosimetric radiosurgery treatment planning tools, feasible treatment plans were developed for each target. The treatment plans generated for the phantom targets showed excellent dose conformity and acceptable dose homogeneity within the target volume. The algorithm was able to generate a radiosurgery plan conforming to the Radiation Therapy Oncology Group (RTOG) guidelines on radiosurgery for every clinical and phantom target examined. CONCLUSIONS: This automated planning method can serve as a valuable tool to assist treatment planners in rapidly and consistently designing conformal multiple isocenter radiosurgery treatment plans.

Algorithms↗
PubMed2003

Analysis of tumor control and toxicity in patients who have survived at least one year after radiosurgery for brain metastases.

PURPOSE: To better evaluate tumor control and toxicity from radiosurgery for brain metastases, we analyzed these outcomes in patients who had survived at least 1 year after radiosurgery. METHODS AND MATERIALS: We evaluated the results of gamma knife stereotactic radiosurgery (SRS) for 208 brain metastases in 137 patients who were followed for a median of 18 months (range 12-122) after radiosurgery. The median patient age was 53 years (range 3-83). Ninety-nine patients had solitary metastases. Thirty-eight had multiple tumors. Sixty-nine patients underwent initial SRS with whole brain radiotherapy (WBRT), 39 had initial SRS alone, and 27 patients had failed prior WBRT. The median treatment volume was 1.9 cm(3) (range 0.05-21.2). The median marginal tumor dose was 16 Gy (range 12-25). The most common histologic types included non-small-cell lung cancer, breast cancer, melanoma, and renal cell carcinoma, which comprised 37.0%, 22.6%, 13.0%, and 9.13% of the lesions, respectively. Forty-five tumors were associated with extensive edema. RESULTS: At 1 and 5 years, the local tumor control rate was 89.6% +/- 2.1% and 62.8% +/- 6.9%, distal intracranial relapse occurred in 23% +/- 3.6% and 67.1% +/- 8.7%, and postradiosurgical sequelae developed in 2.8% +/- 1.2% and 11.4% +/- 3.5% of patients, respectively. Multivariate analysis found that local control decreased with tumor volume (p = 0.0002), SRS without WBRT (p = 0.008), and extensive edema (p = 0.024); distal intracranial recurrence correlated with younger patient age (p = 0.0018); and postradiosurgical sequelae increased with increasing tumor volume (p = 0.0085). CONCLUSION: Long-term control of brain metastases and complication rates in this selective series of patients surviving >or=1 year after radiosurgery were similar to previously reported actuarial estimates. Large metastases and metastases associated with extensive edema can be difficult to control by radiosurgery, particularly without WBRT.

Actuarial Analysis↗
PubMed1998

Stereotactic radiosurgery for cerebral metastatic melanoma: factors affecting local disease control and survival.

PURPOSE: The development of a brain metastasis represents an ominous event for patients with malignant melanoma. We evaluated results after stereotactic radiosurgery (SR) for patients with metastastic melanoma to identify patient outcomes and factors for survival. METHODS: The authors reviewed the management results of 60 consecutive patients with melanoma metastases, with a total of 118 melanoma brain metastases, undergoing SR during a 9-year interval. Of these, 51 also had whole-brain radiation therapy (WBRT). A total of 118 tumors of mean volume of 2.95 ml (range, 0.1-25.5 ml) were treated by SR with a mean margin dose of 16.4 Gy (range, 10 to 20 Gy). Univariate and multivariate analyses were used to determine significant prognostic factors affecting survival in 60 patients. RESULTS: Median survival was 7 months after SR in all 60 patients and 10 months from brain tumor diagnosis (mean follow-up period, 9.3 months). Lack of active systemic disease and a solitary metastasis were associated with improved survival in multivariate analysis (median, 15 months). The imaging-defined local control rate of evaluable tumors (n = 72) was 90% (disappearance = 11%, shrinkage = 44%, and stable = 35%). Local recurrence developed in 7 patients and remote brain disease developed in 14 patients. WBRT combined with radiosurgery did not improve survival nor local tumor control. New brain metastases developed less often when WBRT was added to SR (23% vs. 44%), but this difference was not significant. Only 4 patients (7%) died from progression of a radiosurgery-managed tumor. No patient developed a delayed radiation-related complication, but 3 patients developed delayed intratumoral hemorrhage at the radiosurgery site, 2 of whom had new symptoms. CONCLUSIONS: Stereotactic radiosurgery for melanoma brain metastasis is effective and is associated with few complications. The use of radiosurgery alone is an appropriate management strategy for many patients with solitary tumors.

Adolescent↗
PubMed1999

Fractionated radiosurgery for 9L gliosarcoma in the rat brain.

PURPOSE: Fractionated radiosurgery is being carried out in the clinic to improve the therapeutic ratio of single-dose radiosurgery using various fractionation schemes. Because there is a paucity of experimental radiobiological data in the literature on the tumor response and late-responding normal tissue of critical intracranial structures to radiosurgery, the present animal study was designed to compare the response following a single high dose of radiation with that obtained from calculated fractionated doses of radiosurgery. METHODS AND MATERIALS: Male Fischer rats with 9L gliosarcoma growing in their brains were stereotactically irradiated and assayed for the tumor control rate and brain tissue damage. The radiation dose needed for 50% tumor control (TCD50) was used as the endpoint of the efficacy of radiosurgery. Normal brain damage was measured histologically following a period of time over 270 days. Histological evaluation included hematoxylin-eosin (H & E), Luxol fast blue and periodic acid Schiff (LFB/PAS) for the presence of myelin and glial fibrillary acidic protein (GFAP) for the assessment of astrocytic re-activity. The optical density of optic nerves and chiasms staining with LFB/PAS was quantitatively measured using a computer image analysis to assess the magnitude of demyelination. RESULTS: Radiosurgery (RS) was found to be more effective in curing small tumors than large tumors. The dose required to control 50% of the tumored animals for 120 days was 24, 31, and 40 Gy for 2-, 6-, and 12-day-old tumors, respectively. Using 12-day-old brain tumors, two fractions of 23.5 Gy and three fractions of 18.5 Gy were found to be equivalent to the single dose of 35 Gy for tumor control. For normal brain damages, the visual pathways including optic nerves and chiasm were found to be highly radiosensitive structures. A single dose of 35 Gy produced 100% severe optic neuropathy. The fractionated RS regimens spared substantial optic nerve damage. CONCLUSION: The present data provide a strong radiobiological rationale for the use of fractionated RS in the treatment of tumors located near critical normal structures, including visual pathways. The sparing effect of fractionated RS is greater for late-responding tissues, relative to the rapidly proliferating tumor tissues. This report also characterizes the dose/time tolerance relationship of optic neuropathy after single and fractionated RS.

Animals↗
PubMed2000

Radiosurgery for brain metastases: a score index for predicting prognosis.

PURPOSE: To analyze a prognostic score index for patients with brain metastases submitted to stereotactic radiosurgery (the Score Index for Radiosurgery in Brain Metastases [SIR]). METHODS AND MATERIALS: Actuarial survival of 65 brain metastases patients treated with radiosurgery between July 1993 and December 1997 was retrospectively analyzed. Prognostic factors included age, Karnofsky performance status (KPS), extracranial disease status, number of brain lesions, largest brain lesion volume, lesions site, and receiving or not whole brain irradiation. The SIR was obtained through summation of the previously noted first five prognostic factors. Kaplan-Meier actuarial survival curves for all prognostic factors, SIR, and recursive partitioning analysis (RPA) (RTOG prognostic score) were calculated. Survival curves of subsets were compared by log-rank test. Application of the Cox model was utilized to identify any correlation between prognostic factors, prognostic scores, and survival. RESULTS: Median overall survival from radiosurgery was 6.8 months. Utilizing univariate analysis, extracranial disease status, KPS, number of brain lesions, largest brain lesion volume, RPA, and SIR were significantly correlated with prognosis. Median survival for the RPA classes 1, 2, and 3 was 20.19 months, 7.75 months, and 3. 38 months respectively (p = 0.0131). Median survival for patients, grouped under SIR from 1 to 3, 4 to 7, and 8 to 10, was 2.91 months, 7.00 months, and 31.38 months respectively (p = 0.0001). Using the Cox model, extracranial disease status and KPS demonstrated significant correlation with prognosis (p = 0.0001 and 0.0004 respectively). Multivariate analysis also demonstrated significance for SIR and RPA when tested individually (p = 0.0001 and 0.0040 respectively). Applying the Cox Model to both SIR and RPA, only SIR reached independent significance (p = 0.0004). CONCLUSIONS: Systemic disease status, KPS, SIR, and RPA are reliable prognostic factors for patients with brain metastases submitted to radiosurgery. Applying SIR and RPA classifications to our patients' data, SIR demonstrated better accuracy in predicting prognosis. SIR should be further tested with larger patient accrual and for all patients with brain metastases subjected or not to stereotactic radiosurgery.

Adult↗
PubMed1998

Do we need Monte Carlo treatment planning for linac based radiosurgery? A case study.

The accuracy of conventional empirical and semi-empirical dose calculation algorithms for radiation therapy treatment planning is limited. The main problem is that these algorithms fail to adequately consider the lateral transport of radiation. Most conventional algorithms use measured dose distribution data as input. These data induce an added inaccuracy to stereotactic radiosurgery dose calculations due to the difficulty of acquiring accurate dosimetric data for very small beams; however, since multiple arcs of large solid angles are usually used in stereotactic radiosurgery, the errors introduced by conventional dose algorithms are quite likely to be diluted. The use of Monte Carlo treatment planning for stereotactic radiosurgery has been investigated and described in the present paper. The OMEGA Monte Carlo code system is used as the dose engine in an in-house developed radiosurgery treatment planning system. The Monte Carlo treatment plans are done for two typical clinical cases. In one case, the collimator of 20 mm diameter is used and the lesion is located in the peripheral part of the brain. In the other case, the collimator diameter is 30 mm and the lesion is in the central part of the brain. The resultant dose distributions are compared with those calculated with a conventional dose algorithm which is based on the standard Tissue Maximum Ratio (TMR)/Off Axis Ratio (OAR) formalism. Without the inhomogeneity correction, the conventional algorithm yields accurate relative dose distributions for both cases compared with the Monte Carlo calculations. The absolute dose at the isocenter may be overestimated by the conventional algorithm by 1.5% for the first case and 2.6% for the second case; however, using the method of ratio of TMRs for inhomogeneity correction, the overestimation can be greatly reduced for both cases. The inclusion of the inhomogeneity correction into the conventional dose algorithm does not alter the relative dose distributions. Based on the clinical cases studied, it may be concluded that the conventional dose algorithm is sufficient for radiosurgery treatment planning and the Monte Carlo based radiosurgery treatment planning is unwarranted.

Aged↗
PubMed2002

Local recurrence of metastatic brain tumor after stereotactic radiosurgery or surgery plus radiation.

In this study, we compared the recurrence of metastatic brain tumors after radiosurgery versus after surgery plus radiation, and analyzed the factors associated with the recurrence of brain metastases. Twenty-eight and 35 patients with metastatic brain tumors underwent radiosurgery (52 lesions) and surgery plus radiation (46 lesions), respectively, between 1995 and 2001. The median tumor volume was 1.55 ml (range: 0.02-10.4 ml) in radiosurgery patients and 17.9 ml (range: 0.26-195 ml) in surgery plus radiation patients. The median radiosurgical tumor central and margin doses were 28.9 and 23.8 Gy (range: 20-35 and 25-15 Gy), respectively. The median total dose was 46.7 Gy (range: 30-63 Gy) in the surgery plus radiation group. The recurrence time from surgery plus radiation group (25 months) was significantly longer than that from the radiosurgery group (7.2 months) (p = 0.0199). The factors affecting the recurrence of brain metastases after radiosurgery were size, central dose of radiation and histology (colon vs. others). No factors affected the recurrence of brain metastases after surgery plus radiation. To avoid early recurrences of metastatic brain tumors, surgery plus radiation is the preferable therapeutic modality. The size and histology of brain metastases, and the dose of radiation should be considered for the effective treatment of tumors by radiosurgery.

Adult↗
PubMedDate not supplied

The evolving role of stereotactic radiosurgery for patients with skull base tumors.

Tumors located at the base of the skull are among the most difficult problems that neurosurgeons encounter. Management of patients with skull base tumors must take into account that complete tumor removal is not possible with acceptable morbidity in many patients. Therefore, radiation therapy and stereotactic radiosurgery are commonly performed. The use of radiosurgery for patients with skull base tumors has increased significantly over the past three decades and we now possess a better understanding of the expectations of skull base radiosurgery. For properly selected patients with benign tumors (meningiomas, schwannomas, glomus tumors), tumor control rates between 90 and 100% have been reported. Local control rates for chordomas and chondrosarcomas have ranged from 50 to 70%, but tumor growth adjacent to the treated area (marginal failure) remains a significant problem. Radiosurgery is also commonly performed for patients with malignant skull base tumors as a palliative treatment and symptom relief is common, especially for patients with facial pain related to their tumor. Follow-up beyond 10 years is still needed to better define long-term results of radiosurgery and the incidence of radiation-induced neoplasms after radiosurgery.

Humans↗
PubMed2000

Embolisation of cerebral arteriovenous malformations to assure successful subsequent radiosurgery.

This study investigated the angiographic changes in embolised arteriovenous malformations (AVMs) pre- and post-embolisation and preradiosurgery to clarify the usefulness of embolisation as a pretreatment for radiosurgery and the strategy of embolisation for the radiosurgical success. A total of 37 patients with cerebral AVMs treated over a period of 4 years was investigated. All the AVMs were embolised with N-butyl cyanoacrylate and 2 months later they were treated by radiosurgery. The size of AVM nidus reduced just following the embolisation (mean 21.9 ml to 3.9 ml). The angiogram taken in preparation for radiosurgery showed a further size reduction in the nidus of 16 AVMs, no change in 10 and regrowth in 11. In all the cases where size was reduced, the nidus was densely packed, while all the regrown AVMs were of the diffuse type. Five AVMs disappeared following radiosurgery, all of which were size-reduction or no-change cases. In conclusion, to achieve success in subsequent radiosurgery, nidus embolisation and the occlusion of fistulous and meningeal feeders are mandatory. Imprudent proximal feeder occlusion and the use of embolic materials with a risk of recanalisation should be avoided to prevent regrowth of the nidus, which may lead to errors in planning the radiosurgery to follow.

Adolescent↗
PubMed2001

The treatment of skull base meningiomas--combining surgery and radiosurgery.

While the operative results for treating skull base meningiomas have improved due to modern microsurgical techniques, surgery is still accompanied by a high morbidity rate. Over the last 6 years, we operated on 50 patients with intracranial meningiomas, 23 of which were skull-based lesions. Among these patients with skull base meningiomas, seven (30%) were treated with both surgery and radiosurgery. All patients received standard operative procedures. Five patients received subtotal resections and two patients received partial resections. No mortalities occurred in our series. Following the operations, the clinical status improved in six patients, while only one patient (with a tuberculum sellae meningioma) experienced deterioration of a preexisting visual disturbance. Radiosurgery was performed at a mean of 4.3 months after the operations. One patient was treated by a two-staged radiosurgery regimen in light of the patient's large tumour volume (57.5 cm(3)). The treatment volume of the series ranged from 0.3 to 29.6 cm(3)(mean 11.6 cm(3)), and the minimum dose for the tumours was from 8 Gy to 12 Gy (mean, 11.6 Gy). Tumour regression was observed in three patients (43%) during the follow up period for radiosurgery (mean: 28 months). No patients revealed tumour growth in the follow up period or suffered symptomatic radiation injury. The clinical status remained unchanged in each of the seven patients after radiosurgery. Although we treated only seven patients with skull base meningiomas using surgery combined with radiosurgery, and the follow up period has been short, we believe that such combination treatment may be a very useful option in selected patients.

Adult↗
PubMed1998

Endovascular therapy of brain AVMs prior to radiosurgery.

The purposes of this study were to determine the safety and efficacy of embolization of brain AVMs prior to radiosurgery and to evaluate the total obliteration rate achieved. The brain AVMs of 64 patients were subselectively embolized mainly with NBCA, platinum microcoils and/or PVA. The aim of embolization was the reduction of the target volume and/or the elimination of vascular structures bearing an increased risk of hemorrhage. Presenting symptoms were intracranial hemorrhage in 33 patients, a seizure disorder in 21 patients, and headache in 6 patients. Four AVMs had been detected as an incidental finding. The initial AVM volume was in the range of 0.5 to 84 cc (mean 17 cc). Grading of the AVMs according to the Spetzler-Martin scale showed the following distribution: grade I, 3x; II, 13x; III, 11x; IV, 17x; V, 4x; VI, 16x. A total of 300 endovascular procedures including 47 subselective catheterizations without and 253 with embolization were performed. A size reduction of the AVMs between 10% and 95% (mean 63%, median 70%) was achieved. Neurological symptoms due to treatment complications were transient in 12 patients, of minor clinical significance but permanent in 4 patients. Following radiosurgery, one patient died due to recurrent intracerebral hemorrhage. Three patients are doing well but refused final follow-up angiography. A total of 30 patients is currently within the latency interval after radiosurgery. Radiosurgery failed to obliterate the embolized AVMs in 16 patients. Angiography confirmed complete nidus obliteration in 14 patients. The endovascular treatment of brain AVMs prior to radiosurgery proved safe and effective and may be considered in either high grade or incidental AVMs. AVM obliteration after embolization and radiosurgery is less frequently achieved than after stereotactic irradiation of primarily small AVMs.

Adolescent↗
PubMed2005

Comparative analyses of linac and Gamma Knife radiosurgery for trigeminal neuralgia treatments.

Dedicated linac-based radiosurgery has been reported for trigeminal neuralgia treatments. In this study, we investigated the dose fall-off characteristics and setup error tolerance of linac-based radiosurgery as compared with standard Gamma Knife radiosurgery. In order to minimize the errors from different treatment planning calculations, consistent imaging registration, dose calculation and dose volume analysis methods were developed and implemented for both Gamma Knife and linac-based treatments. Intra-arc setup errors were incorporated into the treatment planning process of linac-based deliveries. The effects of intra-arc setup errors with increasing number of arcs were studied and benchmarked against Gamma Knife deliveries with and without plugging patterns. Our studies found equivalent dose fall-off properties between Gamma Knife and linac-based radiosurgery given a sufficient number of arcs (>7) and small intra-arc errors (<0.5 mm) were satisfied for linac-based deliveries. Increasing the number of arcs significantly decreased the variations in the dose fall-off curve at the low isodose region (e.g. from 40% to 10%) and also improved dose uniformity at the high isodose region (e.g. from 70% to 90%). As the number of arcs increased, the effects of intra-arc setup errors on the dose fall-off curves decreased. Increasing the number of arcs also reduced the integral dose to the distal normal brain tissues. In conclusion, linac-based radiosurgery produces equivalent dose fall-off characteristics to Gamma Knife radiosurgery with a high number of arcs. However, one must note the increased treatment time for a large number of arcs and isocentre accuracies.

Dose-Response Relationship, Radiation↗
PubMed1995

Stereotactic radiosurgery for the definitive, noninvasive treatment of brain metastases.

BACKGROUND: The spread of systemic cancer to the brain is a common complication for cancer patients. Conventional radiotherapy offers modest palliation, and surgery is helpful only for the patient with a single metastasis in an accessible location. Stereotactic radiosurgery, a technique that permits the precise delivery of a high dose of radiation to a small intracranial target while sparing the surrounding normal brain, has been used as an alternative treatment for brain metastases. PURPOSE: Our medical center's 7-year experience with radiosurgery for metastases was reviewed to establish the effectiveness of the treatment and to understand the prognoses in patients so treated. METHODS: Retrospective analysis of hospital records, from 248 consecutive patients (421 lesions) that were treated with radiosurgery between May 1986 and May 1993, was performed. Patients were only excluded for a Karnofsky performance score of less than 70, evidence of acute neurologic deterioration, or tumor diameter more than 4 cm. Median follow-up was 26.2 months. Seventy-six percent of patients had recurrent disease, 69% had evidence of systemic disease, 69% had a single metastasis. Treatment was performed using a 6-MeV linear accelerator. The median tumor volume was 3 cm3. The median treatment dose was 1500 cGy. Whole brain radiotherapy was given to all newly diagnosed patients. Patients were followed by neurological examination and neuroimaging at regular intervals. Local control of disease was defined as a lack of progression of solid-contrast enhancement on computed tomography scan or magnetic resonance imaging. RESULTS: Median overall survival from radiosurgery was 9.4 months. The absence of active systemic disease, younger than 60 years of age, two or fewer lesions, and female sex were significantly associated with increased survival (two-sided P < .05). Actuarial local control rates were approximately 85% at 1 year and 65% at 2 years. Factors associated with a significantly decreased local control rate were location below the tentorium, recurrent tumor, and larger tumor volume (two-sided P < .05). Radioresponsive and radioresistant tumor types had similar control rates. The median drop in Karnofsky performance score at 1 year was 10%. CONCLUSIONS: The results of this retrospective analysis show that radiosurgery is an effective, minimally invasive outpatient treatment option for small intracranial metastases. Results of this study also indicate that radiosurgery not only provides local control rates equivalent to those from surgical series but is also effective in treating patients with surgically inaccessible lesions, with multiple lesions, or with tumor types that are resistant to conventional treatment.

Adolescent↗
PubMed2001

Stereotactic radiosurgery of residual or recurrent craniopharyngioma, after surgery, with or without radiation therapy.

This study evaluated the role of stereotactic radiosurgery in the multimodality management of craniopharyngioma patients whose prior therapies failed. Ten consecutive patients (3 males and 7 females) had radiosurgery for craniopharyngioma during a 10-year interval. Their ages ranged from 9 to 64 years (median, 14.5 years). The median interval between diagnosis and radiosurgery was 46.5 months. In total, 12 stereotactic radiosurgical procedures were performed to control the solid component of the tumor (2 intrasellar and 10 suprasellar tumors). The median tumor volume was 1.35 cm3. One to 9 isocenters with different beam diameters were used; the median marginal dose was 16.4 Gy; and the dose to the optic apparatus was limited to less than 8 Gy. Clinical and imaging follow-up data were obtained at a median of 63 months (range, 13-150 months) from radiosurgery. Overall, 7 of 12 tumors became smaller or vanished within a median of 8.5 months. Prior visual defects objectively improved in 6 patients. One patient with prior visual defect deteriorated further and lost vision 9 months after radiosurgery. Multimodality therapy is often necessary for patients with refractory solid and cystic craniopharyngiomas. Stereotactic radiosurgery is a reasonable option in select patients with small recurrent or residual craniopharyngioma.

Adolescent↗
PubMed1999

Functional radiosurgery.

Although the application of stereotactic radiosurgery for the management of functional brain disorders began in 1951, almost 50 years elapsed before it received appropriate attention. Radiosurgical techniques are used to create image-guided, physiological inactivity or focally destructive brain lesions without neurophysiological guidance. The lack of neurophysiological guidance remains the greatest argument against the use of radiosurgery for selected disorders. Current anatomic targets include the trigeminal nerve (for trigeminal neuralgia), the thalamus (for tremor or pain), the cingulate gyrus or anterior internal capsule (for pain or psychiatric illness), the globus pallidus (for symptoms of Parkinson's disease), and the hippocampus (for epilepsy). The use of radiosurgery as a "lesion generator" is based on extensive animal studies that defined the dose, volume, and temporal response of the irradiated tissue. The usefulness of radiosurgery has been compared with that of microsurgical, percutaneous, and electrode-based techniques used for functional neurological disorders. At present, the long-term results after functional radiosurgery procedures remain to be documented. The current indications and expected outcomes after radiosurgery are discussed.

Animals↗
PubMed2000

Stereotactic radiosurgery in the treatment of metastatic disease to the brain.

OBJECTIVE: In recent years, stereotactic radiosurgery has been growing in popularity as a treatment modality for metastatic disease to the brain. The technique has advantages of reduced cost and low morbidity compared with open surgical treatment. Furthermore, it avoids the potential cognitive side effects of fractionated whole-brain radiotherapy. We undertook this study to determine the usefulness of adjuvant radiation therapy and to determine prognostic factors in patients treated with stereotactic radiosurgery. METHODS: We reviewed our series of patients with metastatic tumors treated using gamma knife stereotactic radiosurgery from August 1994 to February 1999. Nonparametric methods were used to compare treatment subgroups by demographic features including age, Karnofsky Performance Scale score, diagnosis, and systemic disease status. Univariate and multivariate analyses of survival and freedom from progression were performed using Kaplan-Meier and Cox proportional hazards regression techniques. RESULTS: This study included 190 patients harboring 431 lesions who were treated in 263 treatment sessions. The median follow-up after radiosurgery was 36 weeks for all patients. The median actuarial survival from the time of radiosurgery in all patients was 34 weeks. When patients were stratified according to tumor histology, those without melanoma had a median survival of 39 weeks, and those with melanoma had a median survival of 28 weeks. The cause of death could be determined in 122 (92%) of the patients known to have died during the data capture period. For patients harboring melanoma, death was attributable to systemic disease in 31 (47%), to central nervous system-related processes in 29 (44%), and to unknown causes in 6 (9%). For non-melanoma patients, death was attributable to systemic disease in 45 (68%), to central nervous system-related processes in 17 (26%), and to unknown causes in 4 (6%). Significantly improved survival (P = 0.002) was observed in patients with controlled systemic disease. No significant difference in survival could be ascertained for patients presenting with up to four lesions, although patients with a total tumor volume greater than 9 cc had shortened survival. No survival benefit could be demonstrated for whole-brain radiotherapy administered either concomitantly or after radiosurgery. CONCLUSION: Factors correlated with significantly improved survival included controlled systemic disease and non-melanoma histology. We found no significant survival benefit that could be discerned from adjuvant whole-brain radiotherapy in this patient group.

Adult↗
PubMed2000

Radiosurgery for childhood intracranial arteriovenous malformations.

OBJECTIVE: The optimal management of intracranial arteriovenous malformations (AVMs) in children remains controversial. Children with intracranial AVMs present a special challenge in therapeutic decision-making because of the early recognition of their future life-long risks of hemorrhage if they are treated conservatively. The goals of radiosurgery are to achieve complete AVM obliteration and to preserve neurological function. We present long-term outcomes for a series of children treated using radiosurgery. METHODS: The findings for 53 consecutive children who underwent at least 36 months of imaging follow-up monitoring after radiosurgery were reviewed. The median age at the time of treatment was 12 years (range, 2-17 yr). Thirty-one children (58%) presented after their first intracranial hemorrhaging episodes, two (4%) after their second hemorrhaging episodes, and one (2%) after five hemorrhaging episodes. Nineteen children (36%) presented with unruptured AVMs, and a total of 25 children (47%) exhibited neurological deficits. AVMs were graded as Spetzler-Martin Grade I (2%), Grade II (23%), Grade III (36%), Grade IV (9%), or Grade VI (30%). The median AVM volume was 1.7 ml (range, 0.11-10.2 ml). The median marginal dose was 20 Gy (range, 15-25 Gy). RESULTS: Results were stratified according to AVM volumes (Group 1, < or =3 ml; Group 2, >3 ml to < or =10 ml; Group 3, >10 ml). Twenty-eight patients (80%) in Group 1 and 11 (64.7%) in Group 2 achieved complete obliteration. The only patient in Group 3 did not achieve obliteration. Complications included brainstem edema (n = 1) and transient pulmonary edema (n = 1). Four patients experienced hemorrhaging episodes, 30, 40, 84, and 96 months after radiosurgery. Multivariate logistic regression analysis demonstrated that only volume was significantly correlated with obliteration rates (P = 0.0109). CONCLUSION: Radiosurgery is safe and efficacious for selected children with AVMs. The obliteration rates and the attendant low morbidity rates suggest a primary role for stereotactic radiosurgery for pediatric AVMs.

Adolescent↗
PubMed2001

Management of cysts arising after radiosurgery to treat intracranial arteriovenous malformations.

OBJECTIVE: The proper treatment for patients with cyst formation after arteriovenous malformation radiosurgery is unknown. METHODS: The treatment of six patients who developed cysts after arteriovenous malformation radiosurgery is described. Four patients had undergone gamma knife radiosurgery (two patients developed cysts after repeat procedures), and two patients had undergone linear accelerator-based radiosurgery. The median prescription isodose volume at the time of the first radiosurgical procedure was 13.2 cm3 (range, 8.0-28.7 cm3). RESULTS: The cysts were discovered a median of 48 months (range, 24-89 mo) after radiosurgery. Three patients were originally without symptoms, and observation with serial imaging was performed; two of those patients developed symptoms 13 and 40 months later, whereas one patient has remained without symptoms for 51 months. Initial treatments for patients with symptomatic cysts included cyst aspiration (n = 3) and placement of a cystoperitoneal shunt (CPS) (n = 2). The median cyst volume was 14 cm3 (range, 4-63 cm3). Cyst recurrence occurred within 2 months for patients who underwent aspiration alone, necessitating placement of a CPS. Shunt placement eliminated the cysts for four patients, at a median follow-up time of 16 months (range, 9-27 mo). One patient's cyst persisted despite CPS placement, and cyst excision was performed. No morbidity occurred with any of the cyst treatments. CONCLUSION: Cyst formation after arteriovenous malformation radiosurgery may occur many years after the procedure. Although most symptomatic cysts can be effectively treated with CPSs, cyst excision may be necessary if the mass effect is not relieved with the less invasive approach.

Adult↗