Article
Stereotactic interstitial photodynamic treatment of glioblastoma recurrences
Stereotaktische interstitielle photodynamische Behandlung von Glioblastomrezidiven
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Published: | June 26, 2020 |
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Objective: Stereotactic interstitial photodynamic therapy (iPDT) using 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX (PPIX) as a selectively working photosensitizer has been shown to be a feasible treatment option for selected small sized unresectable glioblastoma recurrences. We here present for the first time outcome measurements and the risk profile of salvage iPDT of a large and consecutively treated study cohort. The study was approved by the institutional ethical board.
Methods: From our prospective data base we identified all patients undergoing iPDT of a glioblastoma recurrence after previously performed standard treatment. Patients had to have biopsy-proven glioblastoma recurrences with a maximum diameter of 3 cm not suitable for safe complete resection. Treatment decision in favor of iPDT was an interdisciplinary consensus. A modified 3-D treatment-planning software was used to calculate both the treatment volume and the exact position of the light diffusers within the lesion to ensure complete light irradiation. We estimated time-to-treatment-failure (which had to be proven by biopsy) and post-recurrence survival (PRS) and the risk profile of iPDT. Prognostic factors were obtained from logistic regression models.
Results: A total of 59 patients (median age: 48.5 yrs) were included. A median number of 4 laser fibers were steretoctically implanted. Median irradiation time was one hour. Median time-to-treatment-failure was 6.53 months and median PRS was 12.50 months. The 2- and 5-year PRS rates were 22.0 and 6.1%, respectively. 24 patients developed transient peri-operative complications. There was no permanent morbidity. Neither molecuar, patient- nor treatment-related markers impacted treatment response.
Conclusion: Outcome after iPDT is heterogeneous and cannot currently be predicted. The procedure deserves further prospective evaluation particularly with respect to assumed favorable impact on adapted immunity in selected patients.