Photodynamic therapy (PDT) for malignant brain tumors--where do we stand?
Brendan J Quirk1, Garth Brandal2, Steven Donlon2
1Department of Neurology, Medical College of Wisconsin, Milwaukee, WI, United States.
Introduction:
What is the current status of photodynamic therapy (PDT) with regard to treating malignant brain tumors? Despite several decades of effort, PDT has yet to achieve standard of care.
Purpose:
The questions we wish to answer are: where are we clinically with PDT, why is it not standard of care, and what is being done in clinical trials to get us there.
Method:
Rather than a meta-analysis or comprehensive review, our review focuses on who the major research groups are, what their approaches to the problem are, and how their results compare to standard of care. Secondary questions include what the effective depth of light penetration is, and how deep can we expect to kill tumor cells.
Current Results:
A measurable degree of necrosis is seen to a depth of about 5mm. Cavitary PDT with hematoporphyrin derivative (HpD) results are encouraging, but need an adequate Phase III trial. Talaporfin with cavitary light application appears promising, although only a small case series has been reported. Foscan for fluorescence guided resection (FGR) plus intraoperative cavitary PDT results were improved over controls, but are poor compared to other groups. 5-Aminolevulinic acid-FGR plus postop cavitary HpD PDT show improvement over controls, but the comparison to standard of care is still poor.
Conclusion:
Continued research in PDT will determine whether the advances shown will mitigate morbidity and mortality, but certainly the potential for this modality to revolutionize the treatment of brain tumors remains. The various uses for PDT in clinical practice should be pursued.
Insights
Photodynamic therapy (PDT) shows potential for malignant brain tumors, with necrosis up to 5mm. Further clinical trials are needed to establish PDT as a standard treatment, despite encouraging results in some studies.
Area of Science:
- Oncology
- Medical Physics
- Photochemistry
Background:
- Photodynamic therapy (PDT) has been investigated for malignant brain tumors for decades.
- Despite extensive research, PDT has not yet become a standard treatment for these cancers.
Purpose of the Study:
- To assess the current clinical status of PDT for brain tumors.
- To identify reasons why PDT is not standard of care.
- To review ongoing clinical trials aimed at advancing PDT for brain tumor treatment.
Main Methods:
- Focused review of major research groups and their PDT approaches.
- Comparison of PDT results against standard of care treatments.
- Analysis of light penetration depth and tumor cell kill capabilities.
Main Results:
- Photodynamic therapy can achieve measurable tumor necrosis to a depth of approximately 5mm.
- Cavitary PDT with hematoporphyrin derivative (HpD) shows promise but requires Phase III trials.
- Talaporfin and 5-aminolevulinic acid-based PDT show some improvements but still lag behind standard care.
Conclusions:
- Continued research is essential to determine if PDT advancements can reduce brain tumor morbidity and mortality.
- Photodynamic therapy holds significant potential to revolutionize brain tumor treatment.
- Various applications of PDT in clinical practice warrant further investigation.
