Minimally invasive surgical treatment of glioblastomas using interstitial photodynamic therapy

Aim: to study the possibilities of using interstitial photodynamic therapy as a part of complex therapy, a minimally invasive method of glioblastoma patients’ treatment. Material and methods: The study included 9 patients with glioblastoma who had one tumor focus with a maximum size of up to 3.5 cm and a Karnofsky score of at least 70 points. The study group included 6 (66.7 %) men and 3 (33.3 %) women. The average age of patients was 55.3 ± 9.8 years; 7 (77.8 %) patients had the first relapse of glioblastoma tumor, in 2 cases (22.2 %) glioblastoma was diagnosed for the first time. Photoditazine was used as a photosensitizer (PS), administered intravenously at a dose of 1 mg / kg. Interstitial irradiation was performed using a laser (Latus 2.5 (Atkus, Russia)) with a wavelength of 662 nm and a maximum power of 2.5 W and cylindrical scattering fibers. Spatial precise interstitial irradiation of the tumor volume was planned using special software. The duration of irradiation did not exceed 15 min. The light dose averaged 180 J / cm2. Results: No complications or side effects associated with the introduction of PS were noted in patients in the early postoperative period. Transient increase in neurological deficit after iPDT in the early postoperative period was noted in 2 (22.2 %). In 1 patient an increase in hemiparesis was noted, in another patient dysarthria and dysphasia appeared. At the same time, in one patient with hemiparesis, neurological deficit after surgery persisted for more than five weeks after iPDT, but significant regression of symptoms was noted in the following five weeks. Catamnesis was monitored in all 9 patients. The duration of observation after iPDT was up to 61 months. The main cause of death in all 9 patients was tumor progression. The median overall survival was 29.1 months. The median relapse-free survival was 13.3 months. Conclusion: iPDT is a selective minimally invasive technique with promising results and minimal side effects in the treatment of patients with glioblastomas. The technique is a potential treatment option for small and deep tumors in patients with high surgical risk and for patients with tumor recurrence.