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Purpose: Vasculopathy (VAS) is a significant complication associated with radiation therapy in patients treated for brain tumors. We studied the type, location, severity, timing, and resolution of VAS in children with craniopharyngioma treated with proton radiation therapy (PRT) and evaluated predictors of stenosis (STN) using a novel patient and imaging-based modeling approach.Methods and Materials: Children with craniopharyngioma (n = 94) were treated with 54 Gy relative biological effectiveness PRT in a clinical trial, NCT01419067. We evaluated VAS type, location, severity, and resolution. VAS events were segmented and related to their location, operative corridor, PRT dose, and vascular territory to facilitate mixed effect logistic regression modeling of spatial predictors of STN events.Results: Forty-five (47.9%) patients had 111 instances of confirmed VAS (pre-PRT n = 37, 33.3%). The median time to post-PRT VAS was 3.41 years (95% confidence interval, 1.86-6.11). STN events were observed post-PRT in 23.4% (n = 22) of patients. Post-PRT VAS was detected by cerebral angiogram in 9.6% (n = 9), severe in 4.3% (n = 4), and compensated on perfusion in 2.1% (n = 2). Revascularization was required for 5 (5.3%) patients. Postsurgical, pre-PRT VAS, and PRT dose to unperturbed vessels were predictive of STN. The effect of PRT on STN was negligible within the surgical corridor.Conclusions: VAS often precedes PRT and was the strongest predictor of post-PRT STN. The adverse effect of PRT on STN was only apparent in unperturbed vasculature beyond the operative corridor. [ABSTRACT FROM AUTHOR]

Purpose: The use of stereotactic body radiation therapy (SBRT) in pediatric patients has been underreported. We reviewed practice patterns, outcomes, and toxicity of SBRT in this population.Methods and Materials: In this multi-institutional study, 55 patients with 107 non-central nervous system lesions treated with SBRT between 2010 and 2016 were reviewed. Treatment response was evaluated by Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 and modified RECIST v1.1 criteria for soft-tissue and bone lesions, respectively. Patterns of local failure (LF) were assessed dosimetrically. The cumulative incidence of LF and toxicity were estimated accounting for the competing risk event of death. Predictors of LF were identified through joint frailty models for clustered competing risks.Results: The median (range) dose/fraction was 7 (4.5-25) Gy, the total (range) dose/site was 35 (12-45), and the median (range) number of fractions was 5 (1-9). The radiographic response rates of bone and soft-tissue lesions were 90.6% and 76.7%, respectively. Symptom improvement was observed for 62% of symptomatic sites. A total of 27 LFs were documented, with 14 in-field, 9 marginal, and 4 out-of-field LFs. The 1-year estimated cumulative LF rate, progression-free survival, and overall survival were 25.2% (95% confidence interval [CI], 17.2%-36.1%), 17.5% (95% CI, 9.0%-34.1%), and 61% (95% CI, 48.9%-76.1%), respectively. Lesion type (soft tissue vs bone) was the only significant predictor of LF on multivariable analysis (P = .04), with increased hazard for soft-tissue lesions. No acute or late toxicity of grade 4 or higher was observed; the estimated 1-year cumulative incidence of late toxicity of any grade was 7.5% (95% CI, 3.6%-12.1%).Conclusions: The SBRT was well tolerated and resulted in radiographic response and symptom palliation in most pediatric patients with advanced disease. The 1-year cumulative LF rate of 25% will serve as a benchmark for further modifications to radiation therapy indications, parameters, and combination therapy. [ABSTRACT FROM AUTHOR]

Purpose: To determine the preirradiation baseline association of white matter integrity with neurocognitive function and to assess posttreatment changes in pediatric patients with craniopharyngioma treated with proton therapy.Methods and Materials: Ninety children and adolescents (2-20 years old) with craniopharyngioma were treated with proton therapy (54 Gy[RBE]) in a prospective therapeutic trial. Neurocognitive performance at the postoperative baseline before proton therapy and diffusion tensor imaging (DTI) data acquired at baseline and at annual follow-up were analyzed. Tract-based spatial statistics and structural connectomics were used to derive global and local white matter features from DTI. Baseline DTI features were compared for patients with average and below-average neurocognitive performance. Longitudinal DTI data were analyzed to determine the proton dose effect on white matter structures in relation to the irradiated brain volume and baseline age.Results: Before proton therapy, patients with below-average working memory, processing speed, verbal fluency, verbal learning, or fine motor dexterity exhibited more globally degraded white matter structures compared with their counterparts with average performance, as indicated by lower mean fractional anisotropy, decreased global efficiency, or higher modularity. Surgery, obstructive hydrocephalus, and preoperative hypothalamic involvement appeared to be related to this degradation. In local analyses, tract-based spatial statistics revealed left-lateralized associations with verbal and motor functions, which supported surgical approaches to midline tumors via the right hemisphere. The mean fractional anisotropy of the brain and the global efficiency derived from DTI increased over the 5 years after proton therapy. The rate of increase was lower with larger irradiated brain volumes and in older children.Conclusions: Below-average baseline neurocognitive performance in patients with craniopharyngioma before proton therapy appeared to be related to structural degradation of white matter tracts. Posttherapy longitudinal DTI showed improving trends in global integrity and efficiency measures, particularly in children in whom a smaller brain volume was irradiated. [ABSTRACT FROM AUTHOR]