Interstitial photodynamic therapy of malignant gliomas: survival and follow-up analysis

Stereotactic interstitial photodynamic therapy using 5 aminolevulinic acid is a more upcoming approach for the treatment of malignant gliomas, whose treatment is remaining a major challenge in brain tumor therapy. The therapeutic outcome of 16 patients who underwent 5-ALA iPDT for newly diagnosed glioblastomas, are presented. In addition to the basic survival analysis, MRI data was analyzed concerning image changes after iPDT and the possibility to use these changes as prognostic factor for therapy response. Overall the iPDT showed a progression-free survival (PFS) of 16.4 months and an overall survival (OS) of 28.0 months. A PFS longer than 2-years was seen for 43.8% of iPDT patients. In contrast to this complete tumor resection with consecutive chemoradiation shows 8.9% 2-year PFS. Standard MRI-related prognostic factors of the tumor resection like necrosis-tumor ratio, tumor volume and post-treatment contrast enhancement are not useful for iPDT prognosis. This shows that the MRI interpretation has to be different compared to conventional tumor therapy. The survival results showed that iPDT is a potential treatment option especially for tumors, where standard therapy is not possible. Further studies are needed.