J. Rahimian

COMPARISON OF EARLY COMPLICATIONS FOR PATIENTS WITH CONVEXITY AND PARASAGITTAL MENINGIOMAS TREATED WITH EITHER STEREOTACTIC RADIOSURGERY OR FRACTIONATED STEREOTACTIC RADIOTHERAPY

OBJECTIVEPatients with convexity and parasagittal (CPS) meningiomas treated with stereotactic radiosurgery (SRS) have been shown to be at risk for posttreatment symptomatic peritumoral edema (SPTE). We sought to analyze the pattern of this complication and compare it with the SPTE experienced in our patients treated with fractionated stereotactic radiotherapy. METHODSFrom January 2003 to October 2005, 32 patients with CPS meningiomas were treated. Thirty patients with a total of 38 lesions had sufficient follow-up for analysis. Group A (n = 14) patients were treated with single fraction SRS, and Group B (n = 16) patients were treated with fractionated stereotactic radiotherapy. The lesion volume was different between the two groups with the Group B median volume (7.46 cm3) being larger than that for Group A (2.84 cm3) (P = 0.0008). Conversely age, follow-up, sex, prior surgical events, number of lesions, tumor location, and atypical histology did not differ between these groups. The median marginal dose for patients in Group A was 14 Gy (range, 12.5–18 Gy). For Group B, six patients received a median marginal dose of 50.4 Gy in 28 fractions, and 10 patients received a marginal dose of 25 Gy in five fractions. RESULTSSeven of the 30 patients treated in this series developed posttreatment SPTE. The incidence of SPTE in Group A (six of 14 patients) was significantly higher than that in Group B (one of 16 patients) (P = 0.031). The median time to onset of SPTE in the six patients in Group A was 4 months. In Group B, one patient had onset of SPTE in 3 months. On univariate analysis, larger tumor volume (P = 0.0014) and tumor margin dose >14 Gy in patients undergoing SRS (P = 0.031) was associated with onset of SPTE. Age, previous surgery, and tumor location were not associated with onset of SPTE. CONCLUSIONDespite larger lesion volumes, fractionated stereotactic radiotherapy is associated with less risk of posttreatment SPTE than SRS for patients with CPS meningiomas in our series. For patients treated with SRS, smaller volume and dose <14 Gy seems to be safe. Longer follow-up will be required to compare late complications and tumor control rates in these patients.

Photon-based Fractionated Stereotactic Radiotherapy for Postoperative Treatment of Skull Base Chordomas

Objectives: We report our series of skull base chordoma patients who underwent surgical resection followed by high-dose fractionated stereotactic radiotherapy (FSRT) as an alternative to proton radiotherapy (RT). Methods: Between 2002 and 2009, 12 patients with skull base chordomas without prior radiation history were treated with adjuvant or salvage RT. FSRT with dynamic conformal arcs and intensity-modulated radiation therapy boost was used until 2006 when image-guided intensity-modulated FSRT was instituted. Median dose of 66.6 Gy (range, 48.6 to 68.4 Gy) was delivered in 180 cGy fractions prescribed to the 90% isodose line that covered the target volume to achieve a median isocenter dose of 74 Gy (range, 54 to 76 Gy). Results: Median follow-up was 42 months. Median time from surgery to initiation of RT was 3.6 months. Overall survival was 76.4% at 5 years, and 46.9% and 37.5% of patients were free of progression at 24 and 60 months, respectively. Six patients had disease progression after radiation with a median time to progression of 17.3 months. One patient was salvaged with radiosurgery and surgical resection, with stable disease almost 7 years since diagnosis. Two patients were salvaged with molecular targeted therapy with stable disease at 20 and 23 months. At last follow-up, 9 patients had stable or reduced disease. Conclusions: FSRT as postoperative treatment of skull base chordomas resulted in promising overall survival results comparable with the published literature of particle therapy without significant complications. Our technique for treating skull base chordomas can be considered a safe and less costly alternative to proton RT.

Contemporary methods of radiosurgery treatment with the Novalis linear accelerator system

Radiosurgery has emerged as an indispensable component of the multidisciplinary approach to neoplastic, functional, and vascular diseases of the central nervous system. In recent years, a number of newly developed integrated systems have been introduced for radiosurgery and fractionated stereotactic radiotherapy treatments. These modern systems extend the flexibility of radiosurgical treatment in allowing the use of frameless image-guided radiation delivery as well as high-precision fractionated treatments. The Novalis linear accelerator system demonstrates adequate precision and reliability for cranial and extracranial radiosurgery, including functional treatments utilizing either frame-based or frameless image-guided methods.

Prognostic factors for radiosurgery treatment of trigeminal neuralgia.

OBJECTIVETrigeminal neuralgia treatment results are thought to be highly dependent upon selection criteria. We retrospectively analyzed a series of patients to determine the likelihood of treatment success for patients treated with radiosurgery. METHODSA retrospective analysis of 82 patients treated with linear accelerator radiosurgery was undertaken with a median follow-up period of 18 months. Patients were evaluated with a standard inventory using the Barrow Neurological Institute pain scale as the primary means of outcome measurement. Patients were treated with a linear accelerator using a single isocenter plan delivered via a 4-mm collimator, typically with seven noncoplanar arcs to a peak dose of 85 or 90 Gy in primary treatments and 60 Gy in retreatments. The primary target was the cisternal component of the trigeminal nerve. Posttreatment outcomes were analyzed in light of pretreatment patient characteristics, including age, sex, anticonvulsant responsiveness, quality and pattern of pain, length of disease, number of previous procedures, and radiation dose exposure to the root entry zone. Univariate analysis and multivariate logistic regression analysis were used to determine the prognostic significance of various pretreatment variables. RESULTSGood results as defined by a Barrow Neurological Institute outcome score of IIIb or better were seen in 85.3% of patients. Excellent results as defined by a Barrow Neurological Institute outcome score of I were seen in 49% of patients. The median time to satisfactory improvement of pain was 4 weeks. Only one variable, sensitivity to anticonvulsant medication, was found to be statistically significant in both univariate (P = 0.003) and multivariate analysis (P = 0.025). All other variables analyzed failed to reach statistical significance. Complications were not common, with seven patients (8.5%) developing new-onset hypoesthesia and two patients (2%) developing dry eye symptoms. CONCLUSIONAnticonvulsant responsiveness is the single most important prognostic indicator of treatment success for patients presenting with facial pain. Other predictive factors generally failed to reach statistical significance. Linear accelerator radiosurgery for trigeminal neuralgia is a safe and effective treatment for well-selected patients, with results similar to those obtained with gamma unit radiosurgery.

A comparative study of stereotactic radiosurgery, hypofractionated, and fractionated stereotactic radiotherapy in the treatment of skull base meningioma.

Objectives:To compare the outcomes of skull base meningiomas treated with stereotactic radiosurgery (SRS), hypofractionated stereotactic radiotherapy (hFSRT), and fractionated stereotactic radiotherapy (FSRT). Methods:A total of 220 basal meningiomas in 213 patients were treated using SRS (N=55), hFSRT (N=22), and FSRT (N=143). The median age was 59 years (28 to 84 y). Prior surgery was performed in 74 cases; 39 patients received adjuvant radiotherapy after incomplete resection and 35 patients received salvage radiotherapy after tumor progression. In 146 cases, radiation was the primary therapy. Ten patients had World Health Organization II or III meningiomas. Results:The median follow-up was 32 months (7 to 97 mo). Median tumor volume was 2.8 cm3 (0.10 to 16.94 cm3), 4.8 cm3 (0.88 to 20.38 cm3), and 11.1 cm3 (0.43 to 214.00 cm3) and the median dose was 1250 cGy in 1 fraction to the 80% isodose line (IDL), 2500 cGy in 5 fractions to the 90% IDL, and 5040 cGy in 28 fractions to the 90% IDL for the SRS, hFSRT, and FSRT groups, respectively. Radiographic control was achieved in 91%, 94%, and 95% (P=0.25), whereas clinical response was seen in 89%, 100%, and 91% (P=0.16) in the SRS, hFSRT, and FSRT groups, respectively. Conclusions:There is no significant difference in the radiographic and clinical response in patients with skull base meningioma treated with SRS, hFSRT, or FSRT and thus gives the clinician the impetus to tailor treatment techniques to the location and size of the tumor at presentation.

Control of brain metastases using frameless image-guided radiosurgery

OBJECT Radiosurgery is an important and well-accepted method in the management of brain metastases. Using conventional frame-based techniques, high lesional control rates are expected. The introduction of image-guided techniques allows for improved patient comfort and workflow. Some controversy exists as to the accuracy of imageguided techniques and consequently the impact they might have on control of brain metastases (as opposed to the level of control achieved with frame-based methods). The authors describe their initial 15-month experience with image-guided radiosurgery (IGRS) using Novalis with ExacTrac for management of brain metastases. METHODS The authors reviewed the cases of brain metastasis treated by means of IGRS in their tertiary regional radiation oncology service over a 15-month period. During the study period 54 patients (median age 57.9 years) harboring 108 metastases were treated with IGRS. The median time from cancer diagnosis to development of brain metastasis was 12 months (range 0-144 months). The median tumor volume was 0.98 cm(3) (range 0.03-19.07 cm(3)). The median prescribed dose was 18 Gy to the 80% isodose line (range 14-20 Gy). Lesions were followed with postradiosurgery MR imaging every 2-3 months following treatment. RESULTS The median follow-up period was 9 months (range 0-20 months). Median actuarial survival was 8.6 months following IGRS. Eight patients with 18 lesions died within the first 2 months after the procedure, before scheduled follow-up imaging. Thus 90 lesions (in 46 patients) were followed up with imaging studies. Lesions that were unchanged or reduced in size were considered to be under control. The 6-month actuarial lesion control rate was 88%. Smaller lesions (< 1 cm(3)) had a statistically improved likelihood of complete imaging response (loss of all contrast-enhancement p = 0.01). CONCLUSIONS Image-guided radiosurgical treatment of brain metastases resulted in high rates of tumor control comparable to control rates reported for frame-based methods. High control rates were seen for small lesions in which spatial precision in dose delivery is critical. These data suggests that in regard to lesion control, IGRS using Novalis with ExacTrac is equivalent to frame-based radiosurgery methods.

Hypofractionated stereotactic radiosurgery for treatment of cerebral arteriovenous malformations: outcome analysis with use of the modified arteriovenous malformation scoring system.

Radiosurgery has long been an accepted modality for definitive treatment of cerebral arteriovenous malformations (AVM). Efforts to improve the therapeutic ratio for this indication include use of staged volume procedures and hypofractionation. This study reviews our experience with a cohort of patients treated with hypofractionated radiosurgery. Over a 3year period, 38 patients harboring 39 cerebral AVM were treated with hypofractionated stereotactic radiotherapy. Seventeen of these patients presented due to hemorrhage, four were asymptomatic unruptured lesions and the remainder were symptomatic unruptured lesions. The median AVM volume was 11.43 cc and median modified Radiosurgery-Based Arteriovenous Malformation Score (mRBAS) was 2.02. The median follow-up was 7.32years. Four patients harboring four AVM were lost to follow-up before a result could be ascertained leaving 35 AVM for analysis. Excellent outcomes (AVM obliteration without new deficits) occurred in 17 of 34 (50%) patients and in 18 of 35 (51%) AVM treated. AVM obliteration was seen in 26 of 35 (74%) lesions treated. Two patients died during the follow-up period (6%). A poor result (major deficit without obliteration) was seen in one patient. Of 19 patients harboring AVM with mRBAS >2.0, an excellent outcome was achieved in eight (42%). Hypofractionation for cerebral AVM can result in satisfactory obliteration rates, but with risk of significant complications commensurate with mRBAS. Further study of this technique will be needed to ascertain the degree of incremental improvement, if any, over other radiosurgery treatment methods.

De novo superior cerebellar artery aneurysm following radiosurgery for trigeminal neuralgia

Stereotactic radiosurgery is a commonly used method for treatment of trigeminal neuralgia. Radiation has been known to be a factor in the later development of aneurysms. Aneurysms have been reported to occur after radiation delivered in a variety of methods including both externally delivered radiation radiosurgery and brachytherapy. We report here an incidence of a de novo aneurysm presenting following radiosurgery treatment for trigeminal neuralgia. The patient was treated using frame-based LINAC radiosurgery receiving 90Gy to the mid cisternal extent of the nerve via a 4mm conical collimator. The patient presented with progressive hypoesthesia 11years after treatment. Imaging evaluation demonstrated the presence of an aneurysm abutting the treated trigeminal nerve. The aneurysm was successfully coil embolized. The patients facial hypoesthesia, however, did not improve following embolization. We believe that this is the first report of such an aneurysm occurring after radiosurgery for trigeminal neuralgia. De novo aneurysms are a recognized long term complication of radiotherapy and radiosurgery treatment. This report shows such aneurysms can occur with very small treatment volumes. Late sensory changes following radiosurgery for trigeminal neuralgia should prompt workup for de novo aneurysms as well as other late adverse radiation effects.

Frameless Stereotactic Radiosurgery of Arteriovenous Malformations Using High-Resolution 3-Dimensional Rotational Angiography.

Purpose/Objective(s): Previous studies have shown similar clinical outcome between single or multi-fraction (Fr) radiation therapy for MSCC patients with poor prognosis whereas patients with expected longer survival may require long course radiation therapy to prevent local failure. However, such poor risk group has not yet been clearly identified for daily clinical practice. We examined if the known predictive Tokuhashi scoring system could be adapted in MSCC patients treated with palliative radiation therapy. Materials/Methods: A retrospective review of the treatment outcome of the MSCC patients who received palliative radiation therapy from January 2014 to May 2015 was conducted. The patients were stratified by the Tokuhashi scoring system into group 1(score < 9): expected survival < 6 months, and group 2(score > or equal 9): expected survival > 6 months. Their survival was tested against subsequent systemic therapy (chemotherapy, targeted or hormonal therapy) and other risk factors including age, primary site, visceral metastasis, baseline motor function, prior radiation therapy, radiation therapy fraction (single or multiple). Results: The outcome of 119 patients was studied, 100 (84%) patients have already succumbed. The overall median survival was 55 days (range 4 to 576 days). 93 patients (78.2%) belonged to group 1. The median dose delivered was 25 Gy in 5 Frs (range: 7 Gy in 2 Frs to 40 Gy in 10 Frs). Only 9 patients (7.6%) received singlefraction radiation therapy, all belonging to group 1. Patients belonging to Tokuhashi group 1 had shorter median survival than group 2; 49 and 108 days respectively (P Z 0.02).Among all the patients, subsequent systemic treatment (Hazard ratio [HR] Z 0.354, 95% CI 0.194-0.647, P Z 0.01) and non-visceral metastasis (HR Z 0.593, 95% CI 0.363-0.968, P Z 0.037) were associated with better survival in multivariate analysis. For patients in group 1, primary breast or prostate cancer (HR Z 0.260, 95% CI 0.109-0.620, P Z 0.002) or lung cancer (HR Z 0.425, 95% CI 0.246-0.734, P Z 0.002), non-visceral metastasis (HR Z 0.426, 95% CI 0.236-0.771, P Z 0.0048), multi-fraction (HR Z 0.462, 95% CI 0.2180.982, P Z 0.0447) and subsequent systemic therapy (HR Z 0.424, 95% CI 0.217-0.828, P Z 0.012) were associated with better survival. The survival of a subset of patients in group 1 without subsequent systemic therapy was dismal (median survival only 40 days) and not altered by radiation therapy schedule (P Z 0.198). Conclusion: MSCC comprises of a very heterogeneous group of patients, even under the Tokuhashi grouping, systemic therapy or visceral metastasis may be more important prognostic factors. Further studies are necessary to better select the poor risk group. In clinical practice, singlefraction radiation therapy could be considered in Tokuhashi group 1 patients due to expected short survival, especially those without reasonable systemic treatment options. Author Disclosure: W. Mui: None. T. Lam: None. F. Wong: None. W. Sze: None. S. Tung: None.

Integral Whole Brain Dose from Stereotactic Radiosurgery of 47 Metastatic Lesions: A Dosimetric Case Study

This report describes the case of a 15-year-old male diagnosed with primary ALK-positive adenocarcinoma of the lung metastatic to the brain. He was treated with surgical resection for a single lesion followed by whole brain radiotherapy and subsequently underwent 10 courses of stereotactic radiosurgery for 47 lesions delivered over a four-year period. Currently, all metastatic lesions in the brain are completely resolved or locally controlled.