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Purpose: We evaluated clinical outcomes in the subset of patients who underwent radiotherapy (RT) due to progressive pilocytic astrocytoma within the Multicenter Treatment Study for Children and Adolescents with a Low Grade Glioma HIT-LGG 1996., Patients and Methods: Eligibility criteria were fulfilled by 117 patients. Most tumors (65 %) were located in the supratentorial midline, followed by the posterior fossa (26.5 %) and the cerebral hemispheres (8.5 %). Median age at the start of RT was 9.2 years (range 0.7-17.4 years). In 75 cases, external fractionated radiotherapy (EFRT) was administered either as first-line nonsurgical treatment (n = 58) or after progression following primary chemotherapy (n = 17). The median normalized total dose was 54 Gy. Stereotactic brachytherapy (SBT) was used in 42 selected cases., Results: During a median follow-up period of 8.4 years, 4 patients (3.4 %) died and 33 (27.4 %) experienced disease progression. The 10-year overall (OS) and progression-free survival (PFS) rates were 97 and 70 %, respectively. No impact of the RT technique applied (EFRT versus SBT) on progression was observed. The 5-year PFS was 76 ± 5 % after EFRT and 65 ± 8 % after SBT. Disease progression after EFRT was not influenced by gender, neurofibromatosis type 1 (NF1) status, tumor location (hemispheres versus supratentorial midline versus posterior fossa), age or prior chemotherapy. Normalized total EFRT doses of more than 50.4 Gy did not improve PFS rates., Conclusion: EFRT plays an integral role in the treatment of pediatric pilocytic astrocytoma and is characterized by excellent tumor control. A reduction of the normalized total dose from 54 to 50.4 Gy appears to be feasible without jeopardizing tumor control. SBT is an effective treatment alternative.

Background: Positron emission tomography/computed tomography (PET/CT) is composed of modern CT and PET technology in one machine enabling examinations of patients in one session in the same position. Its value for modern radiation treatment planning is under investigation., Methods: In 53 patients with head-and-neck (n = 11), non-small cell lung (n = 16), prostate (n = 14) and other cancers (n = 12), a PET/CT investigation was performed. During the diagnostic examination process an integrated scan under radiation treatment-planning conditions was included. Interpretation and delineation of macroscopic tumor were done in an interdisciplinary approach. Treatment changes occurred after critical interpretation of the PET/CT findings by the responsible radiotherapist. Analysis is descriptive with regard to changes in treatment intention, mode, radiation volumes and doses., Results: Examinations were well tolerated. CT datasets in treatment position could be used for planning. Delineation of macroscopic tumor led to changes of the planning target volume after PET/CT 15 times, total dose was modified twelve times. PET/CT examinations led to changes of the general treatment mode in 19 cases. Using the separate CT and PET datasets, fusion in the planning software was easily performed in all patients due to the use of the same positioning and immobilization devices in PET/CT., Conclusion: Despite the low number of patients and an expected bias of selection, the first results are encouraging to perform more extended and detailed trials of this technology in radiotherapy planning. Whether PET/CT is superior to PET alone is part of ongoing investigations.