Purpose: Discernment of radiotherapy (XRT) effects vs. tumor activity is difficult in brain tumor patients during the months after XRT when white matter hyperintensities sometimes emerge. We examined brain scans in XRT-treated vs. untreated patients for early-delayed post-XRT effects.
Methods and materials: Brain regions susceptible to XRT injury were examined on magnetic resonance imaging (MRI) for T2-weighted hyperintensities and atrophy in 37 adults with low-grade primary brain tumors (13 nonirradiated and 24 irradiated). Cases evidencing recurrence/growth over the study period were censored. Interactions with age, mood, fatigue, medications, tumor type and grade, extent of resection, and laterality of MRI changes were examined.
Results: Hyperintensity and atrophy ratings over time for the treated and untreated groups were not significantly different. White matter atrophy increased unrelated to XRT. In all patients combined, white matter atrophy and hyperintensities were greater at all time points and more lateralized in surgically treated patients.
Conclusions: Radiotherapy status was not related to changes in MRI ratings during the weeks/months after XRT. Findings contradict assumptions about radiographically evidenced early-delayed XRT effects. Increases in T2-weighted hyperintensities during the 1-6-month period post-conformal radiotherapy for low-grade tumors are likely not related to early-delayed XRT effects.