Evaluation of photodynamic therapy near functional brain tissue in patients with recurrent brain tumors.

INTRODUCTION

Photodynamic therapy (PDT) involves the selective retention of a photosensitizer that upon activation with light mediates tumor cell destruction via the production of singlet oxygen. This study evaluates the toxicity of PDT and a new light-delivery device based on light-emitting diode (LED) technology in selected patients with brain tumors.

METHODS

Twenty patients with recurrent malignant brain tumors received 22 treatments with PDT. Sixteen tumors were supratentorial and four tumors were infratentorial. Patients received IV Photofrin 24 h prior to light exposure starting at 0.75 mg kg(-1). Laser and LED arrays were used to deliver 100 J cm(-2) of light to the sensitized tumors. Fourteen patients received PDT with a laser-balloon adapter, two via interstitial optical fibers and five patients had LED based PDT. At the maximum Photofrin dose of 2.0 mg kg(-1) five patients received laser-balloon adapter light and five patients received LED light. In addition, three patients received LED light with 0.25 mg kg(-1) of Visudine, a benzoporphyrin derivative (BPD). Quantitative analysis of toxicity and time to progression was performed.

RESULTS

Two patients had toxicity consisting of ataxia and facial weakness after treatment with interstitial fibers. Escalating doses of Photofrin were tolerated to the maximum dose of 2.0 mg kg(-1). BPD did not result in additional toxicity. PDT in the posterior fossa or near eloquent brain was tolerated using the LED or laser-balloon adapter. All patients had tumor responses as documented by MRI scan and the mean time to tumor progression after PDT was 67 weeks.

CONCLUSION

PDT with LED balloon adapters (also tunable dye laser) has acceptable toxicity in brain tumor patients. Future studies using more effective photosensitizers could improve local recurrence control.