Proceedings of the 52nd Annual ASTRO Meeting S269

Purpose/Objective(s): Current methods for assessing the response to therapy of glial tumors have limitations and therefore con-troversy exists regarding the best definition of tumor response or progression. Establishing uniform criteria is critical since clinicaltrials rely on these to assess efficacy of standard treatments and novel agents. In this study we sought to compare bi-dimensional andvolumetric MR measurements, as well as clinical assessments as definitions of disease progression after radiation therapy in pe-diatric patients with BSG treated on a Pediatric Brain Tumors Consortium (PBTC) Phase II trial of tipifarnib and radiation (RT).

Materials/Methods: PBTC has completed a phase II study of tipifarnib, a farnesyltransferase inhibitor, administered concurrently withRT in children with newly diagnosed BSGs. For the 37 patients who had 2 or more MRI measurements on treatment, all MRIs werecentrally reviewed by the PBTC Neuro-Imaging Center with bi-dimensional and volumetric measurements obtained retrospectively.

Results: In assessing ‘‘pseudo-progression’’ we asked how many patients met the 25% threshold for progressive disease on the firstpost-radiation scan, done 2 weeks after completion of radiation. For 3 patients, this MRI showed progressive disease and in all 3 ofthese patients disease continued to progress, resulting in death soon thereafter. For 14 of 37 patients, bi-dimensional and volumetricmeasurements documented progressive disease at the same time point. Four patients progressed by volumetric measurements butnever progressed by bi-dimensional measurements; while in only 1 patient disease progressed by bi-dimensional measurementswithout progression by volumetric measurements. In 4 cases disease progression was seen by bi-dimensional measurements earlierthan by volumetric measurements, while in 6 cases tumor volume indicated progressive disease earlier than tumor area. Eighteenpatients remained on study and continued to receive study drug despite meeting the 25% threshold for progressive disease either bytumor volume or area. However, no differences in progression free survival were evident regardless of whether progressive diseasewas defined by tumor volume, tumor area, or institutional decisions.

Conclusions: Among 37 newly diagnosed children with BSG treated with a farnesyltransferase and concurrent radiation no‘‘pseudo-progression’’ was seen. Regardless of whether progressive disease was defined by tumor volume, tumor area, or evalu-ations by the treating sites no differences in progression free survival were evident.

Author Disclosure: D. Haas-Kogan, None; M. Anwar, None; M. Kocak, None; D. Rodriguez, None; M.D. Prados, None;A. Banerjee, None; S.M. Blaney, None; J.M. Boyett, None; L.E. Kun, None; T.Y. Poussaint, None.

2145 Prognostic Factors for Survival and Recurrence in Adult Medulloblastoma

A. V. Krauze1, S. Patel1, S. Ghosh1, W. Roa1, B. Abdulkarim1, A. Murtha1, M. Hamilton2

1Cross Cancer Institute, Edmonton, AB, Canada, 2Tom Baker Cancer Centre, Calgary, AB, Canada

Purpose/Objective(s): We report on prognostic factors for survival and recurrence in adult medulloblastoma patients at twoinstitutions.

Materials/Methods: The charts of 71 consecutive patients between 1944 and 2008 were reviewed. Univariate and multivariateanalysis using the Cox regression model and logistic regression analysis was performed.

Results: Median age of the 48 male and 23 female patients was 27 years (age range, 16-71 years). 65 patients received surgery (48%gross total resection, 44% subtotal resection, 2% exploration/biopsy , 8% unspecified). By Children’s Oncology Group (COG) riskstratification 15 patients (21%) were designated poor risk, 38 patients (54%) standard risk, and 15 patients (21%) unknown. 66patients received radiotherapy and of these 63 patients received craniospinal radiotherapy (CSI) (total posterior fossa dose range,35-56 Gy). 38 (48%) patients received chemotherapy at some point in their treatment (7 concurrent, 31 after recurrence). Mediansurvival from diagnosis was 4.4 years (range, 0-20 years). Of those who recurred, 22 (31%) did so locally, 14 (20%) developed spinalseeding, 4 (6%) developed bone marrow involvement, and 31 (44%) had unknown location. In univariate analysis diagnosis after1990 (p = 0.007) and female gender (p = 0.039) predicted for decreased rates of recurrence. A trend for subtotal resection predictingfor increased rates of spinal recurrence was evident (p = 0.083). CSI and posterior fossa boost were prognostic for both decreasedrecurrence (p = 0.041 (fossa boost), p = 0.0 (CSI) and improved survival (p = 0.047 (fossa boost), p = 0.0 (CSI)). Chemotherapy wasprognostic for decreased recurrence (p = 0.025). Desmoplastic histology, 4th ventricle involvement, tumor enhancement, presenceof hydrocephalus, vermian location and CSF spread at diagnosis did not significantly predict for outcome.

Conclusions: High rates of local and spinal recurrence is a significant issue in adult medulloblastoma. Subtotal resection resulted ina trend towards increased rates of spinal recurrence. CSI and posterior fossa boost were prognostic for both decreased recurrence andincreased survival. Chemotherapy was prognostic for decreased recurrence. Desmoplastic histology and vermian location did notsignificantly predict for outcome. COG risk stratification and Chang staging were not predictive of recurrence patterns or survival.

Author Disclosure: A.V. Krauze, None; S. Patel, None; S. Ghosh, None; W. Roa, None; B. Abdulkarim, None; A. Murtha, None;M. Hamilton, None.

2146 Analysis of Toxicity in Patients with Collagen Vascular Diseases or Multiple Sclerosis Treated with Gamma

Knife Radiosurgery for Intracranial Tumors

D. A. Lowell, E. G. Shaw, J. D. Bourland, A. F. de Guzman, K. E. Ekstrand, T. L. Ellis, K. P. McMullen, M. T. Munley,

S. B. Tatter, M. D. Chan

Wake Forest University School of Medicine, Winston-Salem, NC

Purpose/Objective(s): Previous series have suggested a possible increased rate of toxicity in patients with collagen vascular dis-ease receiving radiotherapy, and with patients with multiple sclerosis receiving brain irradiation. We aimed to assess toxicity inpatients with these cormorbid conditions treated with intracranial radiosurgery.

Materials/Methods: Between January 2004 and April 2009, 6 patients with multiple sclerosis and 14 patients with a collagenvascular disease were treated with gamma knife radiosurgery (GKRS) for intracranial tumors. Treated lesions included 15 totalbrain metastases in 7 patients, 11 benign brain tumors, one low grade glioma, and one cavernous malformation. Electronic recordswere evaluated for each patient to assess for toxicity. Toxicities were graded by the SOMA/LENT scale. In addition, ‘‘rare toxic-ities’’ were characterized as those reported in the scientific literature at an incidence of less than 5% after GKRS.

Results: Median follow-up time was 16 months. Median dose to the tumor margin was 13.0 Gy (range, 12 to 21 Gy) to the 50%isodose line. Median size of tumor treated with radiosurgery was 5.0 cc (range, 0.14 to 7.8 cc). Of the 14 patients with collagen