ABSTRACT
BACKGROUND: Pseudoprogression (PsP) is a recognized phenomenon after radiotherapy (RT) for high-grade glioma but is poorly characterized for low-grade glioma (LGG). We sought to characterize PsP for pediatric LGG patients treated with RT, with particular focus on the role of RT modality using photon-based intensity-modulated RT (IMRT) or proton beam therapy (PBT). METHODS: Serial MRI scans from 83 pediatric LGG patients managed at 2 institutions between 1998 and 2017 were evaluated. PsP was scored when a progressive lesion subsequently decreased or stabilized for at least a year without therapy. RESULTS: Thirty-two patients (39%) were treated with IMRT, and 51 (61%) were treated with PBT. Median RT dose for the cohort was 50.4 Gy(RBE) (range, 45-59.4 Gy[RBE]). PsP was identified in 31 patients (37%), including 8/32 IMRT patients (25%) and 23/51 PBT patients (45%). PBT patients were significantly more likely to have post-RT enlargement (hazard ratio [HR] 2.15, 95% CI: 1.06-4.38, P = 0.048). RT dose >50.4 Gy(RBE) similarly predicted higher rates of PsP (HR 2.61, 95% CI: 1.20-5.68, P = 0.016). Multivariable analysis confirmed the independent effects of RT modality (P = 0.03) and RT dose (P = 0.01) on PsP incidence. Local progression occurred in 10 patients: 7 IMRT patients (22%) and 3 PBT patients (6%), with a trend toward improved local control for PBT patients (HR 0.34, 95% CI: 0.10-1.18, P = 0.099). CONCLUSIONS: These data highlight substantial rates of PsP among pediatric LGG patients, particularly those treated with PBT. PsP should be considered when assessing response to RT in LGG patients within the first year after RT.
Subject(s)
Brain Neoplasms/radiotherapy , Glioma/radiotherapy , Photons/adverse effects , Proton Therapy/adverse effects , Radiation Injuries/pathology , Adolescent , Brain Neoplasms/pathology , Child , Child, Preschool , Disease Progression , Female , Follow-Up Studies , Glioma/pathology , Humans , Infant , Male , Neoplasm Grading , Radiation Injuries/etiology , Radiotherapy Dosage , Retrospective Studies , Survival RateABSTRACT
BACKGROUND: Stereotactic radiation therapy (SRT) of brain metastases is used with good effect around the world, but no consensus exists regarding which prognostic factors that are related to favourable or unfavourable prognosis after the treatment. A better definition of these factors will ensure a more precise application of the treatment. MATERIAL AND METHODS: A consecutive cohort of the 198 patients treated for brain metastases with SRT without concurrent whole-brain radiation therapy at our department from 2001 to 2012 was retrospectively analysed. RESULTS: Median survival was seven months and median time to clinical cerebral progression was eight months. The multivariate analysis revealed age ≥ 65 years, Performance Status ≥ 2, extracranial metastases and size of metastasis > 20 mm as independent prognostic factors related to shorter survival. No factors were independently related to clinical cerebral progression. CONCLUSION: We identified four prognostic factors related to survival after SRT for brain metastases. The grouping of patients by these factors is useful to determine the level of treatment. We discourage the delivery of SRT to patients with 3-4 unfavourable prognostic factors because of the very short median survival of two months.