Patterns of Tumor Progression Following BNCT of Glioblastoma Multiforme
The recurrence patterns after conventional adjuvant treatment of glioblastoma multiforme has been analyzed in the past. The most consistent pattern seen in these studies is the predominance of local recurrence.1,2,3 Hochberg and Pruitt were the first investigators to discover that the gross and microscopic tumors were within 2 cm of the contrast-enhancing tumor margin on pre-terminal CT scans in 83% of the patients.3 This became the basis for target volume definition in radiotherapy. In the first several BNCT protocols, this target definition was adopted. However, there has been considerable consternation over the significance of peritumoral edema when planning radiation fields. Biopsy and autopsy studies from the Mayo Clinic and Duke University have shown infiltrating cells in edematous regions.1,2 If so, peritumoral hypodense regions may be at risk for tumor recurrence and should be included in the treatment volume. However, this observation is still in dispute because the malignant nature of the infiltrating cells has not been proven. In the studies by Wallner et al. from Memorial Sloan Kettering Cancer Center, no tendency for tumor recurrence in edematous areas was shown.4 The present paper reports on the recurrence patterns seen on our BNCT trial, in particular, with relation to regions of peritumoral edema.
KeywordsGlioblastoma Multiforme Boron Neutron Capture Therapy Peritumoral Edema Astrocytic Glioma Target Volume Definition
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