Interstitial photodynamic therapy of glioblastoma: An MRI-based follow-up analysis

As the most common primary malignant brain tumor with a devastating survival perspective, glioblastoma treatment remains a major challenge in medicine. Among recent approaches, 5-aminolevulnic acid (5-ALA) mediated interstitial photodynamic therapy (iPDT) has shown promising results. 16 patients with de-novo glioblastoma treated with iPDT were retrospectively analyzed regarding survival and characteristic tissue regions discernible in recorded MRI data. These regions were segmented at different stages and analyzed, especially regarding their impact on survival. The iPDT cohort showed a median progression-free survival (PFS) of 16.4 months and a median overall survival (OS) of 28.0 months. 10 of 16 patients experienced prolonged survival (≥ 24 months). In comparison to other therapies, the iPDT cohort maintained a significantly prolonged PFS and OS. Known prognostic factors for survival after standard treatment were not found to be relevant for this cohort, such as necrosis-tumor ratio, tumor volume and post-treatment contrast enhancement. In this study, iPDT has shown its potential, especially by a large fraction of prolonged survival. Prognosis-related parameters can be derived from patient data and MR imaging data, but their interpretation has to be adapted in comparison to standard-of-care.