Photodynamic applications in brain tumors: a comprehensive review of the literature

Abstract

Introduction: GBM is the comment glioma. GBM-outcome had not changed much over two decades despite leaps in medical technology. Fewer than 25% survive 2 years. There is no jacket that fits all GBMs. This paper reviews the evidence for PDT in GBMs.

Rationale: Maximum safe resection is supported by level-II evidence. PDT-technology (PDTT) provides means to maximize safe resection. PDTT paints GBM red in contrast to brain because of selective uptake and retention of photosensitizers. Exposure to specific light wave produces cytotoxic singlet oxygen. PDT-APPLICATIONS: (1) Fluorescence image guided biopsy to sample high grade components of what looks like low grade glioma on MRI, 89% sensitive. (2) Fluorescence image guided surgery for maximum safe surgical resection is >84% sensitive, achieves complete resection in >65% and prolongs tumor free survival (1 observational and 2 RCT, p < 0.001). (3) Photodynamic treatment supported by several observational studies with combined total of >1000 patients and 3 RCT used PDT in GBMs. PDT was highly selective, safe, significantly improved good quality survival, and delayed tumor relapse (p < 0.001).

Safety: PDT had a very high safety track record, thromboembolism 2%, brain-oedema 1.3%, and skin photosensitivity complications 1-3%.

Conclusion: PDT in GBMs is safe, selective, and sensitive and leads to significant prolongation of good quality survival, delay in tumor relapse and significant reduction of further interventions. It would be impractical, impossible and probably unethical to randomize patients between PDT and placebo, in the same way it would be unethical to carry out a RCT to prove that the parachute saves lives.