Proceedings of the 51st Annual ASTRO Meeting S507

Materials/Methods: A total of 82 lesions in 78 patients (median age 8.9 years) who received CRT between 8/1997 and 08/2006were evaluated using MRI performed before, during (Weeks 3 and 5) and every 3–6 months after CRT (54 Gy) through five years.A total of 1196 MRI studies contributed to this report. Lesions were serially assessed for characteristics of enhancement, cyst for-mation or expansion and measured in 3 dimensions (anterior-posterior, transverse and superior-inferior). The imaging sequencethat best demonstrated the tumor at the time of the initial evaluation was used throughout the study. Increasing and decreasing en-hancement was recorded and the composition of the lesion was described according to the development or change in cystic com-ponents.

Results: Patients were followed for a median of 60.1 months (range, 8.8–65.2 months). Enhancement at the initiation of CRTwas noted in 89% (73 of 82) of the lesions and decreased in 67.1% (55 of 82) with a median time of 7.2 months (range, 0.5–36.20 months) after CRT. An increase in the 3-dimensional volume of the tumor complex was noted in 25 lesions duringtreatment. Increasing cystic components were noted in 46.3% (38 of 82) of lesions with a median time of 4.2 months (range,0.2–24 months); 71.1% (27 of 38) of these lesions eventually decreased in size. Approximately 40.2% (33 of 82) of lesionsdid not change; 75.8% (25 of 33) enhanced prior to CRT. Local tumor progression occurred in 9 patients (median 54.1months, range, 17.2 – 83.9). Four failures occurred due to increasing tumor size, 1 due to increasing enhancement, and 4due to increasing size and enhancement. Thirty-one lesions in 30 patients had a median maximum increase in tumor volumeof 24.4% (range, 1.1–332.7), at a median time of 4.9 months (range, 0.2–15.27 months) without developing progressivedisease.

Conclusions: Decreasing enhancement and increasing cyst formation characterize the response of pediatric LGG to CRT. Thesechanges occur predictably in the majority of cases. Because cyst formation or change in tumor volume may occur during CRT, werecommend MRI during treatment to identify changes that would affect tumor coverage. Serial evaluation is required to documenttumor progression. Increasing tumor size during the first year of CRT is common. Most patients who experience local tumor pro-gression have changes in tumor volume or enhancement more than one year after treatment.

Author Disclosure: M. Naik, None; L.P. Berle, None; T.E. Merchant, None.

2723 Radiotherapy for Pediatric and Young Adult Soft Tissue Sarcoma: The University of Florida Experience

K. B. Smith1, D. J. Indelicato1,2, J. A. Knapik3, C. G. Morris1, J. Kirwan1, R. A. Zlotecki1, M. T. Scarborough3, C. Gibbs3,R. B. Marcus2

1University of Florida Shands Cancer Center, Gainesville, FL, 2University of Florida Proton Therapy Institute, Jacksonville, FL,3University of Florida, Gainesville, FL

Purpose/Objective(s): Pediatric and young adult soft tissue sarcomas are a rare and heterogeneous group of tumors. This studyevaluated prognostic factors, outcomes, and complications in patients under 30 years old with nonrhabdomyosarcoma soft tissuesarcoma (NRSTS) treated at the University of Florida with radiotherapy over a 36-year period.

Materials/Methods: One hundred twenty-two patients under 30 years old with NRSTS were treated with curative intent at theUniversity of Florida between 1972 and 2008. The most common histological tumor subtypes were synovial sarcoma (25 patients),malignant fibrous histiocytoma (21 patients), and malignant peripheral nerve sheath tumor (15 patients). The mean age at radio-therapy was 22 years (range, 2 to 30 years). Ninety-three patients had high-grade tumors. Forty-nine, 51, and 22 patients receivedpreoperative, postoperative, and definitive RT, respectively. Prognostic factors for survival, local recurrence, and distant recurrencewere analyzed.

Results: The median followup was 5.5 years (range, 0.3–30.4 years). The actuarial estimates of 5-year overall survival and disease-free survival (DFS) were 59% and 73%. Ninety-three percent of all deaths were disease related. Early AJCC stage, early IntergroupRhabdomyosarcoma Study (IRS) group, microscopically negative margins, tumor\8 cm, absence of neurovascular invasion, andlow/intermediate-grade histology were associated with superior DFS. The actuarial 5-year local control rate was 80%. Early IRSgroup, absence of neurovascular or bone invasion, extremity site, resectability, and microscopically negative margins were asso-ciated with superior local control. Although 70% of local recurrences initially occurred in the absence of metastases, all patientswith a local failure ultimately died of their disease. The rate of NCI Common Toxicity Criteria (CTCAE v3) Grade 3–5 treatmentcomplication was 7%. No secondary malignancies were observed.

Conclusions: In this large single-institution study, we found unresectable tumors and involvement of vital structures to be poorprognostic factors for both local progression and survival. This study helps characterize the therapeutic ratio of radiotherapy inpediatric and young adult sarcoma patients. Our data suggests that local relapse compromises survival and provides a basis foridentifying high-risk patients in whom treatment intensification may be justified.

Author Disclosure: K.B. Smith, None; D.J. Indelicato, None; J.A. Knapik, None; C.G. Morris, None; J. Kirwan, None; R.A. Zlo-tecki, None; M.T. Scarborough, None; C. Gibbs, None; R.B. Marcus, None.

2724 Patterns of Failure after Craniospinal Irradiation, Intensity Modulated Radiation Therapy (IMRT) Boost

and Chemotherapy for Medulloblastoma

A. Paulino1,2, A. Mazloom3, M. South1, B. Teh1, F. Okcu3,2, J. Su3,2, E. Butler1, M. Chintagumpala3,2

1The Methodist Hospital, Houston, TX, 2Texas Children’s Hospital, Houston, TX, 3Baylor College of Medicine, Houston, TX

Purpose/Objective(s): Intensity modulated radiation therapy (IMRT) has been used to minimize high doses of radiation (RT) tonormal surrounding tissues such as the cochlea. Concern has been raised regarding failure patterns after IMRT boost as "marginalmisses" may be more frequent with "tightening" of the high dose region. The purpose of this study is to determine the patterns offailure after craniospinal irradiation (CSI), IMRT boost and chemotherapy for medulloblastoma.

Materials/Methods: From January 1997 to December 2006, 60 patients with a median age of 7.8 years (range, 2.8 to 18 years)and medulloblastoma underwent resection, RT and chemotherapy. There were 42 boys and 18 girls; risk category was standard-risk(SR) in 40 and high-risk (HR) in 20. For SR patients, CSI dose was 18.0–23.4 Gy followed either by (1) IMRT posterior fossa (PF)

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boost to 36 Gy followed by IMRT tumor bed (TB) boost to 54.0–55.8 Gy (n = 32) or (2) IMRT TB boost to 55.8 Gy (n = 8). For HRpatients CSI dose was 36.0–39.6 Gy followed by either (1) IMRT PF boost to 54.0–55.8 Gy (n = 13) or (2) TB boost to 54–55.8 Gy(n = 7). Chemotherapy was cisplatin and cytoxan-based according to SJMB96, SJMB03 or according to COG A9961 protocol.Median follow-up was 63 months (range, 19 to 127 months) for surviving patients.

Results: The 5- year overall survival (OS) and progression-free survival (PFS) rates for all patients were 72.4% and 70.2%, re-spectively. They were 79.1% and 77.7% for SR patients and 59.4% and 56.0% for HR patients (p = 0.095 for OS, p = 0.05 forPFS, log–rank test). A total of 16 recurrences have occurred (8 in SR and 8 in HR patients). Median time to recurrence was25.5 months (32.5 mos for SR and 15.5 mos for HR patients). For SR patients, 5 had leptomeningeal, 2 had isolated TB and 1had isolated non-TB PF failure while for HR patients, 6 had leptomeningeal and 2 had leptomeningeal and TB failure. Mediancochlear dose was 35.3 Gy for SR and 42.8 Gy for HR patients.

Conclusions: Only 1 isolated non-TB PF failure occurred in the 60 patients treated. Leptomeningeal failure was the most commonpattern of relapse both in SR and HR patients. This study demonstrates that the use of an IMRT boost is not associated with excessnon-TB PF relapse.

Author Disclosure: A. Paulino, None; A. Mazloom, None; M. South, None; B. Teh, None; F. Okcu, None; J. Su, None; E. Butler,None; M. Chintagumpala, None.

2725 The Incidence of Isolated Testicular Relapse after Stem Cell Transplantation with Total Body Irradiation

without Testicular Boost

E. Yoo1, J. Song1, H. Kim2, S. Chung1

1Dept. of Radiation Oncology, St. Mary’s Hospital, College of Medicine,The Catholic University,Seoul, Republic of Korea,2Dept. of Pediatrics, St. Mary’s Hospital, College of Medicine,The Catholic University,Seoul, Republic of Korea

Purpose/Objective(s): Testicular relapse after stem cell transplantation (SCT) is one of the most common sites of extramedul-lary relapse of acute lymphoblastic leukemia(ALL). There was no definite protocol for preventing isolated testicular relapse(ITR)after SCT with total body irradiation(SCT-TBI). We adopted a guideline of TBI without testicular boost unless there was sus-picious of testicular infiltration prior to SCT. The aim of this study is to analyze ITR incidence and to compare that with otherliteratures.

Materials/Methods: From January 1995 to December 2005, one hundred ten patients with ALL were treated with SCT-TBI with-out testicular boost. The age range was 1 year to 20 years (median 12 years). TBI were treated with dose range from 4 Gy in 2fractions over 1 day to 13.2 Gy in 8 fractions twice daily over 4 days (median 12 Gy in 6 fractions) with bilateral technique using6MV or 10MV photon energy. All ITR after SCT-TBI without testicular boost were treated with 24 Gy in 12 fractions over 3 weekswith electron energy.

Results: Median follow-up was 46 months (range, 4–131 months) from SCT infusion. Three patients developed ITR(2.7%). Firstpatient with positive Philadelphia chromosome had ITR in 9 months. He has remained complete remission after testicular irradi-ation with chemotherapy for 117 months. Second patient developed testicular recurrence in 5 months followed by bone mar-row(BM) and central nervous system(CNS) in 11 months from SCT. He died in 13 months from SCT. Third patient developedtesticular recurrence in 21 months followed by BM and CNS relapses in 44 months from SCT. Second CNS relapse was occurredin 90 months from complete remission. He is alive in extramedullary relapses at 128 months from SCT.

Conclusions: This study shows lower ITR incidence than other studies using SCT-TBI without testicular boost (range, 14–24%).In addition, this result is compatible with other study using SCT-TBI with testicular boost (2.5%). Even though ITR occur afterSCT-TBI without testicular boost, complete remission could be obtained by testicular irradiation with chemotherapy. Thereforewe suggest testicular boost could be omitted in SCT-TBI of ALL. Further clinical study with large patient number is needed toconfirm this result.

Author Disclosure: E. Yoo, None; J. Song, None; H. Kim, None; S. Chung, None.

2726 Postoperative Radiation Improves Overall Survival in Children Age \3 Years with Intracranial

Ependymoma

M. Koshy1, S. Rich1, T. E. Merchant2, W. F. Regine1, Y. Kwok1

1University of Maryland Medical Center, Baltimore, MD, 2St Jude Children’s Research Hospital, Memphis, TN

Purpose/Objective(s): Concerns regarding long-term toxicities have led to the avoidance of postoperative radiation (RT) in chil-dren age\3 years with intracranial ependymoma. We investigated the impact of postoperative RT on disease control in childrenage \ 3 years and compared their outcomes to other age groups using a national database.

Materials/Methods: Patients diagnosed with intracranial ependymoma and treated between 1988–2005 were chosen from theSEER database for analysis. Patients were classified according to treatment: surgery alone versus surgery followed by RT. Vari-ables used in the analysis included age, gender, SEER registry, tumor size, location and grade, extent of surgery, and year of di-agnosis. Overall survival was estimated using the Kaplan-Meier method and hazard ratios were calculated based on multivariableCox proportional hazards models.

Results: A total of 1095 patients were selected: 22% were \ 3 years, 25% were 3–20 years, and 53% were . 20 years. Surgeryversus surgery followed by RT were administered to 65% and 35% (Age\3 years), 30% and 70% (age 3–20 years) and 52% and48% of patients (age . 20 years), respectively. With a median follow-up of 3.5 years (range, 0.1–18 years), the 3 year overallsurvival was 80% for Grade 1 versus 80% for Grade 2 versus 55% for Grade 3 patients (p \ 0.001). The 3 year overall survivalwas 62% for patients who underwent a biopsy or subtotal resection versus 77% for those who underwent gross total resection(p \ 0.001). The 3 year overall survival was 61% for children age \ 3 years, 83% ages 3–20 years, and 69% for patients . 20years (p \ 0.001). Multivariable analysis revealed postoperative radiation [HR 0.8, 95% CI 0.6–0.9], and gross total resection[HR 0.6, 0.5–0.8] to be associated with improved overall survival. Higher tumor grade [HR 1.9, 1.5–2.5] was associated with