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Stereotactic interstitial photodynamic therapy of circumscribed malignant gliomas using 5-aminolevulinic acid (5-ALA): clinical results of a pilot study
Stereotaktische interstitielle photodynamische Therapie von zirkumskripten malignen Gliomen mit 5-aminolaevulinic acid (5-ALA): Klinische Ergebnisse einer Pilotstudie
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Veröffentlicht: | 11. April 2007 |
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Objective: Photodynamic therapy (PDT) might have the potential to improve local tumour control in selected patients. However, uncertainties concerning dosimetry and photosensitizer (PS)-distribution as well as therapy-related side-effects have limited the clinical impact of PDT in brain-tumors in the past. The present pilot-study was performed 1. to establish the concept of stereotactic interstitial PDT (iPDT) using 5-ALA as PS in a clinical setting and 2. to evaluate its clinical impact.
Methods: iPDT was considered to be indicated for patients with a minimum Karnofsky Performance Status (KPS) of 70 with a “circumscribed” deep seated/eloquently located recurrence of a malignant glioma after prior multimodal therapy with a maximum diameter of 2.5 cm. All operations were performed under general anaesthesia. Patients received 20mg/Kg 5-ALA 1 h pre-operatively. After tumour-histology had been verified by stereotactic serial biopsy, 3D-multimodal-treatmentplanning (CT, MRT, FET-PET) followed by stereotactic implantation (3 mm burrhole, parallel electrode placement) of up to 6 laser-probes was performed. Irradiation time was 60 min (Ceralas PDT Diode Laser: wavelength 633nm, power 200mW/cm (biolitec AG, Jena, Germany)). Follow-up MRI was performed at 24 h, 4 weeks and than in 3-month-intervals post-operatively. Reference point was date of iPDT.
Results: Between October 2002 and June 2004 13 adult patients (mean age 51, range 31-69 years, 5 female/8 male, mean tumour volume 7.9 ml) were included. The applied volume-dose was in the range of 1000 - 1500 J/cm3. Early MRI follow-up showed a complete resolution of the contrast-enhanced lesion in 9 patients and a partial response in the other 4. No enhanced treatment-induced brain oedema was observed. There was a transient treatment related morbidity (increased hemiparesis) in 2 patients. Median follow-up was 13 months. Median survival was 13 months (range 4-49 months). The 1-year-survival rate was 54% (2 patients still alive at last follow-up).
Conclusions: Clinical outcome showed a huge variety with 4 long-term survivors (>24 months). The obviously present therapeutic effect cannot only be ascribed to apoptosis or necrosis of tumour-cells induced by iPDT alone, but also to other factors like the activation of the immune system. A further (prospective) clinical evaluation is currently subject of an ongoing Phase II study at our institution.