Increased cochlear radiation dose predicts delayed hearing loss following both stereotactic radiosurgery and fractionated stereotactic radiotherapy for vestibular schwannoma.

PURPOSE: Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) are noninvasive therapies for vestibular schwannomas providing excellent tumor control. However, delayed hearing loss after radiation therapy remains an issue. One potential target to for improving hearing rates is limiting radiation exposure to the cochlea. METHODS: We retrospectively reviewed 100 patients undergoing either SRS with 12 Gy (n = 43) or fSRT with 50 Gy over 28 fractions (n = 57) for vestibular schwannoma. Univariate and multivariate analysis were carried out to identify predictors of hearing loss as measured by the Gardner Robertson scale after radiation therapy. RESULTS: Deterioration of hearing occurred in 30% of patients with SRS and 26% with fSRT. The overall long term (> 2 year) progression rates were 20% for SRS and 16% for fSRT. Patients with a decrease in their Gardner Robertson hearing score and those that loss serviceable hearing had significantly higher average minimal doses to the cochlea in both SRS and fSRT cohorts. ROC analysis showed that a cut off of 5 Gy and 35 Gy, for SRS and fSRT respectively, predicted hearing loss with high sensitivity/specificity. CONCLUSION: Our data suggests the minimal dose of radiation that the cochlear volume is exposed to is a predictor of delayed hearing loss after either SRS or fSRT. A threshold of 5 Gy/35 Gy may lead to improved hearing preservation after radiotherapy. Further prospective multi center studies can further elucidate this mechanism.

Long-term Outcomes With Ifosfamide-based Hypofractionated Preoperative Chemoradiotherapy for Extremity Soft Tissue Sarcomas.

OBJECTIVES: The objective of this study was to analyze outcomes for patients with soft tissue sarcoma of the extremities using neoadjuvant ifosfamide-based chemotherapy and hypofractionated reduced dose radiotherapy, followed by limb-sparing surgery. MATERIALS AND METHODS: An Institutional Review Board (IRB)-approved retrospective review of patients treated at a single institution between 1990 and 2013 was performed. In total, 116 patients were identified who received neoadjuvant ifosfamide-based chemotherapy and 28 Gy in 8 fractions of preoperative radiation (equivalent dose in 2 Gray fractions, 31.5 Gy [α/ß 10] 36.4 Gy [α/ß 3]) followed by limb-sparing surgery. Local recurrence (LR), distant failure (DF), and overall survival (OS) were calculated. Univariate and multivariate analysis for LR, DF, and OS were performed using Cox analysis. Statistical significance was set at a P<0.05. RESULTS: Median follow-up was 5.9 years (range, 0.3 to 24 y). Actuarial LR at 3/6 years was 11%/17%, DF at 3/6 years was 25%/35%, and OS at 3/6 years was 82%/67%. On multivariate analysis, only a positive surgical margin was significantly correlated with worse local control (P=0.005; hazard ratio [HR], 18.33; 95% confidence interval (CI), 2.41-139.34). Age over 60 years (P=0.03; HR, 2.34; 95% CI, 1.10-4.98) and tumor size over 10 cm compared with tumor size ≤5 cm (P=0.03; HR, 3.32; 95% CI, 1.15-9.61) were associated with worse OS. CONCLUSIONS: Soft tissue extremity sarcoma patients treated using reduced dose hypofractionated preoperative radiotherapy in combination with ifosfamide-based chemotherapy shows acceptable local control and warrants further investigation.

Tomotherapy improves local control and changes failure patterns in locally advanced malignant pleural mesothelioma.

PURPOSE: The purpose of the study was to determine whether intensity modulated radiation therapy delivered via helical tomotherapy improves local control (LC) after pleurectomy/decortication (P/D) for malignant pleural mesothelioma compared with 3-dimensional conformal radiation therapy (3D-CRT). METHODS AND MATERIALS: Forty-five consecutive patients were treated with adjuvant radiation to 45 Gy in 1.8 Gy fractions after P/D between 2006 and 2014; 23 received 3D-CRT, and 22 received tomotherapy. Kaplan-Meier analysis was used to calculate overall survival, time to in-field or local failure (LF), and time to out-of-field failure. The Student t test and Fisher exact test were used to detect between-group differences. RESULTS: Median follow-up time was 19.4 months and 12.7 months for the 3D-CRT and tomotherapy groups, respectively. Eighty-two percent of patients had T3/T4 disease, and 64% had positive nodes; 17.4% and 41% of patients in the 3D-CRT and tomotherapy groups had nonepithelioid histology, respectively. Mean planning target volume dose, percentage of planning target volume receiving 100% of the prescription dose, and lung doses were significantly greater with tomotherapy (P < .05), but toxicity rates (including radiation pneumonitis rates) were equivalent. LC was significantly improved with tomotherapy on Kaplan-Meier analysis with outcomes censored at 2 years (P < .05); uncensored, this became a trend (P = .06). Median time to LF was 19 months with tomotherapy and 10.9 months in 3D-CRT (the latter interval being less than the median follow-up in the tomotherapy group). On univariate analysis, treatment modality was the only significant predictor of LC (P < .05). Isolated LF was significantly more frequent with 3D-CRT (P < .05). Conversely, isolated out-of-field failure was significantly more frequent with tomotherapy (P < .05). Overall survival and out-of-field control were not significantly different. CONCLUSION: Tomotherapy after P/D for malignant pleural mesothelioma is associated with improved target coverage that translates into improved LC compared with 3D-CRT. This is related to a change in failure patterns, with isolated LF being more common in the 3D-CRT group and isolated out-of-field failures predominating in the tomotherapy group.

Evaluation of high ipsilateral subventricular zone radiation therapy dose in glioblastoma: a pooled analysis.

PURPOSE: Cancer stem cells (CSCs) may play a role in the recurrence of glioblastoma. They are believed to originate from neural stem cells in the subventricular zone (SVZ). Because of their radioresistance, we hypothesized that high doses of radiation (>59.4 Gy) to the SVZ are necessary to control CSCs and improve progression-free survival (PFS) or overall survival (OS) in glioblastoma. METHODS AND MATERIALS: 173 patients with glioblastoma pooled from 2 academic centers were treated with resection followed by chemoradiation therapy. The SVZ was segmented on computed tomography to calculate radiation doses delivered to the presumptive CSC niches. The relationships between high SVZ doses and PFS and OS were examined using Cox proportional hazards models. Five covariates were included to estimate their impact on PFS or OS: ipsilateral and contralateral SVZ doses, clinical target volume dose, age, and extent of resection. RESULTS: Median PFS and OS were 10.4 and 19.6 months for the cohort. The mean ipsilateral SVZ, contralateral SVZ, and clinical target volume doses were 49.2, 35.2, and 60.1 Gy, respectively. Twenty-one patients who received high ipsilateral SVZ dose (>59.4 Gy) had significantly longer median PFS (12.6 vs 9.9 months, P=.042) and longer OS (25.8 vs 19.2 months, P=.173). On multivariate analysis, high radiation therapy doses to ipsilateral SVZ remained a statistically significant independent predictor of improved PFS but not of OS. The extent of surgery affected both PFS and OS on multivariate analysis. CONCLUSION: High radiation therapy doses to ipsilateral CSC niches are associated with improved PFS in glioblastoma.

A child with gemcitabine-induced severe radiation recall myositis resulting in a compartment syndrome.

Chemotherapeutic induction of radiation recall (RR) is a rare event in which a chemotherapeutic agent given days to years after radiation therapy causes an inflammation reaction of the tissues within the irradiated area-"recalling" increased radiation effects to that area. In this unique case, a 14-year-old girl with a synovial sarcoma of the forearm was treated with neoadjuvant chemotherapy and radiation therapy. Gemcitabine was administered in an adjuvant setting inducing a RR reaction. The severity of the inflammation resulted in a forearm myositis secondarily causing a compartment syndrome that was treated with several prolonged courses of corticosteroids. The symptoms of RR and compartment syndrome have resolved 1 year postonset, although magnetic resonance imaging continues to show myositis and soft-tissue edema. This case highlights the need to maintain a heightened awareness to recognizing the signs and symptoms of RR and the potential severity of RR in pediatric cancer patients in conjunction with chemotherapeutic agents used more frequently in adults.

Image-guided linear accelerator-based spinal radiosurgery for hemangioblastoma.

PURPOSE: To retrospectively review the efficacy and safety of image-guided linear accelerator-based radiosurgery for spinal hemangioblastomas. METHODS: Between August 2004 and September 2010, nine patients with 20 hemangioblastomas underwent spinal radiosurgery. Five patients had von Hipple-Lindau disease. Four patients had multiple tumors. Ten tumors were located in the thoracic spine, eight in the cervical spine, and two in the lumbar spine. Tumor volume varied from 0.08 to 14.4 cc (median 0.72 cc). Maximum tumor dimension varied from 2.5 to 24 mm (median 10.5 mm). Radiosurgery was performed with a dedicated 6 MV linear accelerator equipped with a micro-multileaf collimator. Median peripheral tumor dose and prescription isodose were 12 Gy and 90%, respectively. Image guidance was performed by optical tracking of infrared reflectors, fusion of oblique radiographs with dynamically reconstructed digital radiographs, and automatic patient positioning. Follow-up varied from 14 to 86 months (median 51 months). RESULTS: Kaplan-Meier estimated 4-year overall and solid tumor local control rates were 90% and 95%, respectively. One tumor progressed 12 months after treatment and a new cyst developed 10 months after treatment in another tumor. There has been no clinical or imaging evidence for spinal cord injury. CONCLUSIONS: Results of this limited experience indicate linear accelerator-based radiosurgery is safe and effective for spinal cord hemangioblastomas. Longer follow-up is necessary to confirm the durability of tumor control, but these initial results imply linear accelerator-based radiosurgery may represent a therapeutic alternative to surgery for selected patients with spinal hemangioblastomas.

Phase II study of pre-irradiation chemotherapy for childhood intracranial ependymoma. Children's Cancer Group protocol 9942: a report from the Children's Oncology Group.

PURPOSE: Standard therapy for childhood intracranial ependymoma is maximal tumor resection followed by involved-field irradiation. Although not used routinely, chemotherapy has produced objective responses in ependymoma, both at recurrence and in infants. Because the presence of residual tumor following surgery is consistently associated with inferior outcome, the potential impact of pre-irradiation chemotherapy was investigated. METHODS: Between 1995 and 1999, the Children's Cancer Group undertook a Phase II trial of pre-irradiation chemotherapy in children 3-21 years of age with intracranial ependymoma and radiological evidence of post-operative residual tumor. RESULTS: Of 84 patients, 41 had residual tumor, and were given four cycles of cisplatin-based chemotherapy prior to irradiation. Of 35 patients fully evaluable for response to chemotherapy, 14 (40%) demonstrated complete response, 6 (17%) partial response, 10 (29%) minor response or stable disease, and 5 (14%) demonstrated progressive tumor growth. For the entire group, 5-year overall survival (OS) and event-free survival (EFS) was 71 ± 6%, and 57 ± 6%, respectively. The pre-irradiation chemotherapy group demonstrated EFS comparable to that of patients with no residual tumor who received irradiation alone (55 ± 8% vs. 58 ± 9%, P = 0.45). Any benefit of chemotherapy was restricted to patients with greater than 90% tumor resection. CONCLUSIONS: Children with near total resection of ependymoma may benefit from pre-irradiation chemotherapy. Patients with subtotal resection have inferior outcome despite responses to chemotherapy, and should be considered for second-look surgery prior to irradiation. Pediatr Blood Cancer 2012; 59: 1183-1189. © 2012 Wiley Periodicals, Inc.

Stereotactic radiation therapy for progressive residual pilocytic astrocytomas.

This report shows the results of stereotactic radiation therapy for progressive residual pilocytic astrocytomas. Medical records of patients who had undergone stereotactic radiation therapy for a progressive residual pilocytic astrocytoma were reviewed. Between 1995 and 2010, 12 patients with progression of a residual pilocytic astrocytoma underwent stereotactic radiation therapy at UCLA. Presentation was headache (4), visual defects (3), hormonal disturbances (2), gelastic seizures (2) and ataxia (1). MRI showed a cystic (9), mixed solid/cystic (2) or solid tumor (1); located in the hypothalamus (5), midbrain (3), thalamus (2), optic chiasm (1) or deep cerebellum (1). Median age was 21 years (range 5-41). Nine tumors received stereotactic radiotherapy (SRT). Three tumors received stereotactic radiosurgery (SRS), two of them to their choline positive regions. SRT median total dose was 50.4 Gy (40-50.4 Gy) in a median of 28 fractions (20-28), using a median fraction dose of 1.8 Gy (1.8-2 Gy) to a median target volume of 6.5 cm(3). (2.4-33.57 cm(3)) SRS median dose was 18.75 Gy (16.66-20 Gy) to a median target volume of 1.69 cm(3) (0.74-2.22 cm(3)). Median follow-up time was 37.5 months. Actuarial long-term progression-free and disease-specific survival probabilities were 73.3 and 91.7 %, respectively. No radiation-induced complications were observed. Stereotactic radiation therapy is a safe and effective modality to control progressive residual pilocytic astrocytomas. Better outcomes are obtained with SRT to entire tumor volumes than with SRS targeting choline positive tumor regions.

Radiation options for high-grade gliomas.

Radiotherapy has become a part of the standard treatment of high-grade gliomas. Studies have shown that high-dose radiation results in more effective tumor control but at the cost of radionecrosis and other radiation-related side effects. Despite advancing techniques in stereotaxy and precise radiotherapy delivery techniques, studies published for stereotactic radiosurgical treatment of high-grade gliomas have not been unanimous, with large trials showing no survival benefit compared with conventional conformal radiotherapy. New imaging modalities have been studied with the hope to improve accuracy in the planning of radiosurgical treatments. However, further large scale studies are needed to confirm these results.

Single-institution, multidisciplinary experience with surgical resection of primary chest wall sarcomas.

INTRODUCTION: Primary chest wall sarcomas are rare mesenchymal tumors and their mainstay of therapy is wide surgical resection. We report our single-institution, multidisciplinary experience with full-thickness resection for primary chest wall sarcomas. METHODS: A retrospective review of our prospectively maintained databases revealed that 51 patients were referred for primary chest wall sarcomas from 1990 to 2009. RESULTS: All patients required resections that included rib and/or sternum. Twenty-nine patients (57%) had extended resections beyond the chest wall. Forty-two patients (82%) required prosthetic reconstruction and 17 patients (33%) had muscle flap coverage. Overall, 51% (26/51) of patients received neoadjuvant therapy. Seventy-three percent (11/15) of high-grade soft tissue sarcomas, 77% (10/13) of high-risk bony sarcomas, and 67% (4/6) of desmoid tumors were treated with induction therapy. Negative margins were obtained in 46 patients (90%). There were no perioperative mortalities. Eight patients (16%) experienced complications. Local recurrence and metastasis was detected in 14 and 23%. Five-year overall and disease-free survivals were 66% and 47%, respectively. Favorable prognostic variables for survival included age ≤50 years, tumor volume ≤200 cm, desmoid tumor, bony tumor, chondrosarcoma, and low-grade soft tissue sarcoma. CONCLUSIONS: We report our multidisciplinary experience with primary chest wall sarcomas that included induction therapy in the majority of high-risk soft tissue and bony sarcomas and desmoid tumors. Despite aggressive preoperative treatments, acceptable surgical results with low morbidity and mortality can be achieved. Neoadjuvant systemic therapy may reduce local and distant recurrence and improve overall survival.

Accelerator-based stereotactic radiosurgery for brainstem metastases.

BACKGROUND: Stereotactic radiosurgery represents a noninvasive alternative treatment for intracranial metastases. OBJECTIVE: To investigate the treatment outcome of linear accelerator-based stereotactic radiosurgery (linac-SRS) for brainstem metastases. METHODS: We retrospectively reviewed our database of patients who were diagnosed with brainstem metastases and underwent linac-SRS between 1997 and 2008 at the University of California, Los Angeles. RESULTS: A total of 45 patients with 48 brainstem metastases were treated. The median target volume was 0.40 mL (range, 0.02-5.70 mL), and median prescription dose was 14 Gy (range, 10-17 Gy) at 90% isodose curve. The median survival time was 11.6 months. Longer survival time was associated with higher Karnofsky performance status. The local control rate was 92% at 6 months and 88% at 1 year. Univariate analysis demonstrated a significant relationship between local control and tumor volume (≤0.4 mL vs >0.4 mL, P = .023) and SRS mode (conventional circular arc vs dynamic conformal arc, P = .044). There was a trend toward improved local control and prescription dose >14 Gy (P = .059). Two patients had brainstem complications following treatment, and the complication rate was 4.7% at 2 years. Serious morbidity occurred with 17 Gy. CONCLUSION: Linac-SRS using a median dose of 14 Gy provided excellent local control in patients with brainstem metastases less than 0.4 mL with relatively low serious morbidity. The results of the study support the use of linac-SRS for patients with brainstem metastases. We advocate 14 to 16 Gy, given the high local control rate and low complication rate with this dose.

Dedicated linear accelerator radiosurgery for trigeminal neuralgia: a single-center experience in 179 patients with varied dose prescriptions and treatment plans.

PURPOSE: Dedicated linear accelerator radiosurgery (D-LINAC) has become an important treatment for trigeminal neuralgia (TN). Although the use of gamma knife continues to be established, few large series exist using D-LINAC. The authors describe their results, comparing the effects of varied target and dose regimens. METHODS AND MATERIALS: Between August 1995 and January 2008, 179 patients were treated with D-LINAC radiosurgery. Ten patients (5.58%) had no clinical follow-up. The median age was 74.0 years (range, 32-90 years). A total of 39 patients had secondary or atypical pain, and 130 had idiopathic TN. Initially, 28 patients received doses between 70 and 85 Gy, with the 30% isodose line (IDL) touching the brainstem. Then, using 90 Gy, 82 consecutive patients were treated with a 30% IDL and 59 patients with a 50% IDL tangential to the pons. RESULTS: Of 169 patients, 134 (79.3%) experienced significant relief at a mean of 28.8 months (range, 5-142 months). Average time to relief was 1.92 months (range, immediate to 6 months). A total of 31 patients (19.0%) had recurrent pain at 13.5 months. Of 87 patients with idiopathic TN without prior procedures, 79 (90.8%) had initial relief. Among 28 patients treated with 70 Gy and 30% IDL, 18 patients (64.3%) had significant relief, and 10 (35.7%) had numbness. Of the patients with 90 Gy and 30% IDL at the brainstem, 59 (79.0%) had significant relief and 48.9% had numbness. Among 59 consecutive patients with similar dose but the 50% isodoseline at the brainstem, 49 patients (88.0%) had excellent/good relief. Numbness, averaging 2.49 on a subjective scale of 1 to 5, was experienced by 49.7% of the patients, CONCLUSIONS: Increased radiation dose and volume of brainstem irradiation may improve clinical outcomes with the trade-off of trigeminal dysfunction. Further study of the implications of dose and target are needed to optimize outcomes and to minimize complications.

Treatment of giant cerebral arteriovenous malformation: hypofractionated stereotactic radiation as the first stage.

BACKGROUND: Treatment of giant cerebral arteriovenous malformations (AVMs) remains a challenge. OBJECTIVE: To propose hypofractionated stereotactic radiotherapy (HSRT) as a part of staged treatment, and evaluate its effect by analyzing AVM volume changes. METHODS: From 2001 to 2007, 20 AVMs larger than 5 cm were treated by HSRT and followed up using magnetic resonance imaging. Patients' median age was 34 years (8-61 years). Eleven patients presented with hemorrhage and 9 with seizure. Ten patients had previous embolization and radiosurgery had failed in 4. Thirteen AVMs (65%) were classified as Spetzler-Martin grade V and 7 as grade IV. Median pretreatment volume was 46.84 cm³ (12.51-155.38 cm³). Dose was 25 to 30 Gy in 5 to 6 daily fractions. Median follow-up was 32 months. RESULTS: Median AVM volume decreased to 13.51 cm³ (range, 0.55-147.14 cm³). Residual volume varied from 1.5% to 98%. Volume decreased 44% every year on average. We noted that 6-Gy fractions were more effective (P = .040); embolized AVM tended to respond less (P = .085). After HSRT, we reirradiated 4 AVMs, with 3 amenable to single dose and one with fractions. After HSRT, one patient had an ischemic stroke and one had increased seizure frequency. One AVM bled during follow-up (2.06%/year). No complete obliteration was confirmed. CONCLUSION: HSRT can turn some giant AVMs manageable for single-dose radiosurgery. Six-Gray fractions were better than 5-Gy and routine embolization seemed unhelpful. There was no increase in bleeding risk with this approach. Future studies with longer follow-up are necessary to confirm our observation.

Initial clinical experience with image-guided linear accelerator-based spinal radiosurgery for treatment of benign nerve sheath tumors.

BACKGROUND: Stereotactic radiosurgery has proven a safe and effective treatment of cranial nerve sheath tumors. A similar approach should be successful for histologically identical spinal nerve sheath tumors. METHODS: The preliminary results of linear accelerator-based spinal radiosurgery were retrospectively reviewed for a group of 25 nerve sheath tumors. Tumor location was cervical 11, lumbar 10, and thoracic 4. Thirteen tumors caused sensory disturbance, 12 pain, and 9 weakness. Tumor size varied from 0.9 to 4.1 cm (median, 2.1 cm). Radiosurgery was performed with a 60-MV linear accelerator equipped with a micro-multileaf collimator. Median peripheral dose and prescription isodose were 12 Gy and 90%, respectively. Image guidance involved optical tracking of infrared reflectors, fusion of amorphous silicon radiographs with dynamically reconstructed digital radiographs, and automatic patient positioning. Follow-up varied from 12 to 58 months (median, 18). RESULTS: There have been no local failures. Tumor size remained stable in 18 cases, and 7 (28%) demonstrated more than 2 mm reduction in tumor size. Of 34 neurologic symptoms, 4 improved. There has been no clinical or imaging evidence for spinal cord injury. One patient had transient increase in pain and one transient increase in numbness. CONCLUSIONS: Results of this limited experience indicate linear accelerator-based spinal radiosurgery is feasible for treatment of benign nerve sheath tumors. Further follow-up is necessary, but our results imply spinal radiosurgery may represent a therapeutic alternative to surgery for nerve sheath tumors. Symptom resolution may require a prescribed dose of more than 12 Gy.

Image-guided radiosurgery for spinal tumors: methods, accuracy and patient intrafraction motion.

Image-guided frameless extracranial radiosurgery has become an established treatment option; however, without a frame to restrict patient movements, intrafraction field mispositioning becomes more probable. The primary aim of this study is to determine the intrafraction motion of spinal radiosurgery patients. This aim was approached in two steps. First, a phantom study demonstrated that the system can detect movements accurately within 0.1 mm and rotational changes within 0.2 degrees. Second, patient positioning and monitoring were carried out for a group of 15 patients with 20 treatment sites. For the patient pool in the study, vertebral anatomy movement was observed to vary as much as 3 mm between sequential measurements and could occur in as little as 5 min. These results suggest a need for intrafraction patient monitoring and correctional shifts, even for patients whose overall treatment times are expected to be relatively short. Small relative rotations with standard deviations of less than 1.5 degrees were observed. The small relative rotational movements observed do not, alone, justify patient monitoring using the image-guidance system during the treatments of generally small radiosurgical targets.

Stereotactic radiation treatment for recurrent nonbenign meningiomas.

OBJECT: The authors analyzed the results of stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) for the treatment of recurrent meningiomas that were described at initial resection as showing aggressive, atypical, or malignant features (nonbenign). METHODS: Twenty-five patients who underwent SRS and/or SRT for nonbenign meningiomas between December 1992 and August 2004 were included. Thirteen of these patients underwent treatment for multiple primary or recurrent lesions. In all, 52 tumors were treated. All histological sections were reviewed and reclassified according to World Health Organization (WHO) 2000 guidelines as benign (Grade I), atypical (Grade II), or anaplastic (Grade III) meningiomas. The median follow-up period was 42 months. Seventeen (68%) of the cases were reclassified as follows: WHO Grade I (five cases), Grade II (11 cases), and Grade III (one case). Malignant progression occurred in eight cases (32%) during the follow-up period; these cases were considered as a separate group. The 3-year progression-free survival (PFS) rates for the Grades I, II, and III, and malignant progression groups were 100, 83, 0, and 11%, respectively (p < 0.001). In the Grade II group, the 3-year PFS rates for patients treated with SRS and SRT were 100 and 33%, respectively (p = 0.1). After initial treatment, 22 new tumors required treatment using SRS or SRT; 17 (77%) of them occurred inside the original resection cavity. Symptomatic edema developed in one patient (4%). CONCLUSIONS: Stereotactic radiation treatment provided effective local control of "aggressive" Grade I and Grade II meningiomas, whereas Grade III lesions were associated with poor outcome. The outcome of cases in the malignant progression group was intermediate between that of the Grade II and Grade III groups, with the lesions showing a tendency toward malignancy.

Brainstem and trigeminal nerve changes after radiosurgery for trigeminal pain.

PURPOSE: To evaluate the significance of radiological changes on follow-up MRIs after SRS for TN. MATERIALS AND METHODS: Thirty-seven patients with follow-up MRI because of paresthesias, bilateral treatment, or failure were analyzed regarding pain outcome and complications. Mean age was 64.4 years; 14 underwent previous treatment. Twenty-nine had ETN, 5 secondary TN due to tumor or multiple sclerosis, and 3 had atypical TN. Ninety gray was prescribed for 20 patients, 70 Gy for 5, and 80/85 Gy for 2. A 5-mm collimator was used in 32 (88.9%) cases. Mean follow-up was 15 months (range, 4-52 months). RESULTS: Excellent/good pain relief was sustained in 67% of cases at 13 months' follow-up. Enhancement on MRIs was observed in 21 cases (56.75%) with nerve enhancement in 9, pons enhancement in 4, pons-nerve enhancement in 4, and tumor enhancement in 4. Magnetic resonance images were unremarkable in 16 cases. Pain recurred in 4 cases (5.5-10 months). Pons enhancement correlated with pain relief (P = .0087) but not with nerve enhancement (P = .22). Incidence of slight paresthesias was 66.6%. No anesthesia dolorosa or ophthalmologic problems were observed. Paresthesias correlated with enhancement (P = .02), but not with brainstem volume encompassed by the 20%, 30%, and 50% isodoseline (P = .689, .525, .908). Enhancement free probability at 12 months was 48.5% (Kaplan-Meier). CONCLUSIONS: Pons enhancement seems to be prognostic for pain relief without higher incidence of complications. Pons volume irradiated did not predict enhancement occurrence. Radiation delivery to the brainstem-REZ interface seems to improve pain outcome, although more paresthesias should be expected.

Stereotactic radiotherapy for the treatment of acoustic neuromas.

OBJECT: The authors sought to assess the safety and efficacy of stereotactic radiotherapy when using a linear accelerator equipped with a micromultileaf collimator for the treatment of patients with acoustic neuromas. METHODS: Fifty patients harboring acoustic neuromas were treated with stereotactic radiotherapy between September 1997 and June 2003. Two patients were lost to follow-up review. Patient age ranged from 20 to 76 years (median 59 years), and none had neurofibromatosis. Forty-two patients had useful hearing prior to stereotactic radiotherapy. The fifth and seventh cranial nerve functions were normal in 44 and 46 patients, respectively. Tumor volume ranged from 0.3 to 19.25 ml (median 2.51 ml). The largest tumor dimension varied from 0.6 to 4 cm (median 2.2 cm). Treatment planning in all patients included computerized tomography and magnetic resonance image fusion and beam shaping by using a micromultileaf collimator. The planning target volume included the contrast-enhancing tumor mass and a margin of normal tissue varying from 1 to 3 mm (median 2 mm). All tumors were treated with 6-MV photons and received 54 Gy prescribed at the 90% isodose line encompassing the planning target volume. A sustained increase greater than 2 mm in any tumor dimension was defined as local relapse. The follow-up duration varied from 6 to 74 months (median 36 months). The local tumor control rate in the 48 patients available for follow up was 100%. Central tumor hypodensity occurred in 32 patients (67%) at a median of 6 months following stereotactic radiotherapy. In 12 patients (25%), tumor size increased 1 to 2 mm at a median of 6 months following stereotactic radiotherapy. Increased tumor size in six of these patients was transient. In 13 patients (27%), tumor size decreased 1 to 14 mm at a median of 6 months after treatment. Useful hearing was preserved in 39 patients (93%). New facial numbness occurred in one patient (2.2%) with normal fifth cranial nerve function prior to stereotactic radiotherapy. New facial palsy occurred in one patient (2.1 %) with normal seventh cranial nerve function prior to treatment. No patient's pretreatment dysfunction of the fifth or seventh cranial nerve worsened after stereotactic radiotherapy. Tinnitus improved in six patients and worsened in two. CONCLUSIONS: Stereotactic radiotherapy using field shaping for the treatment of acoustic neuromas achieves high rates of tumor control and preservation of useful hearing. The technique produces low rates of damage to the fifth and seventh cranial nerves. Long-term follow-up studies are necessary to confirm these findings.

Functional stereotactic radiosurgery involving a dedicated linear accelerator and gamma unit: a comparison study.

OBJECT: The purpose of this work was to investigate the targeting and dosimetric characteristics of a linear accelerator (LINAC) system dedicated for stereotactic radiosurgery compared with those of a commercial gamma knife (GK) unit. METHODS: A phantom was rigidly affixed within a Leksell stereotactic frame and axial computerized tomography scans were obtained using an appropriate stereotactic localization device. Treatment plans were performed, film was inserted into a recessed area, and the phantom was positioned and treated according to each treatment plan. In the case of the LINAC system, four 140 degrees arcs, spanning +/-60 degrees of couch rotation, were used. In the case of the GK unit, all 201 sources were left unplugged. Radiation was delivered using 3- and 8-mm LINAC collimators and 4- and 8-mm collimators of the GK unit. Targeting ability was investigated independently on the dedicated LINAC by using a primate model. Measured 50% spot widths for multisource, single-shot radiation exceeded nominal values in all cases by 38 to 70% for the GK unit and 11 to 33% for the LINAC system. Measured offsets were indicative of submillimeter targeting precision on both devices. In primate studies, the appearance of an magnetic resonance imaging-enhancing lesion coincided with the intended target. CONCLUSIONS: Radiosurgery performed using the 3-mm collimator of the dedicated LINAC exhibited characteristics that compared favorably with those of a dedicated GK unit. Overall targeting accuracy in the submillimeter range can be achieved, and dose distributions with sharp falloff can be expected for both devices.

Novalis Shaped Beam Radiosurgery of arteriovenous malformations.

OBJECT: The authors studied outcomes and complications in patients who harbored arteriovenous malformations (AVMs) and underwent stereotactic radiosurgery involving the Novalis shaped beam unit. METHODS: Between January 1998 and January 2002, 83 patients were treated with radiosurgery at University of California, Los Angeles. The mean patient age was 37.8 years. Forty-four patients completed follow up. There were 24 women. Sixteen patients underwent repeated radiosurgery. Embolization was performed in 13 patients and radiosurgery alone in 31. The mean follow-up period after embolization was 54.4+/-21.9 months and 37.4+/-14.6 months for radiosurgery alone. The mean peripheral dose was 15 Gy (range 12-18 Gy). The mean preradiosurgery lesion volume was 9.7+/-11.9 ml for radiosurgery alone and 16.2+/-11.3 ml for embolization. The AVMs in 13 patients (29.8%) were Spetzler-Martin Grade II, 12 (27.5%) were Grade III, eight (18.2%) Grade IV, and five (11.3%) were Grade V and VI each. Spetzler-Martin grade, volume, and peripheral dose were analyzed in consideration to outcome. A positive trend (p = 0.086) was observed between Spetzler-Martin grade and obliteration rate. Volume per se did not predict obliteration (p = 0.48). A peripheral dose of 18 Gy was shown to be the most important predictor for occlusion (p = 0.007). The overall obliteration rate was 52.5%. A transient complication was noticed in one case (2.3%) and but no permanent deficits due to radiosurgery have been detected so far. Three patients (6.8%) bled after radiosurgery. CONCLUSIONS: The range of the prescribed peripheral dose was narrow. An association between the mean peripheral dose of 15 Gy, high conformality, and homogeneous dose distribution permitted no permanent complications. Volume per se did not correlate with outcome. The next step will be to increase the peripheral dose shaping the beam and to achieve higher obliteration rates without increasing complications.