Optimal light dose for interstitial photodynamic therapy in treatment for malignant brain tumors

Abstract

Background and Objective:The primary goal was to determine the maximal tolerable light dose that can be administered to patients undergoing multifiber interstitial photodynamic therapy (PDT) of malignant brain tumors at a fixed dose of photosensitizer. Study Design/Materials and Methods: Eighteen patients (12 glioblastomas, 5 anaplastic astrocytoma, and 1 malignant ependymoma) were included in this study. The total light dose delivered to the tumor was divided into three groups of six patients each: 1,500-3,700 J, 3,700-4,400 J, and 4,400-5,900 J. Results: Five patients (all glioblastomas) demonstrated postoperative permanent neurologic deficits. None of the patients in 1,500-3,700 J, two patients in 3,700-4,400 J, and three patients in 4,400-5,900 J had neurologic deficits. Glioblastomas recurred more often than anaplastic astrocytomas. Increasing the light dose did not make a difference in local/regional control of glioblastomas. Patients with anaplastic astrocytomas survived (mean, 493 days) longer than patients with glioblastomas (mean, 116.5 days) after PDT. Four patients had prolonged survival (more than a year) after PDT. Conclusions: Increasing the total light dose delivered to the tumor increases the odds of having a permanent neurologic deficit but does not increase survival or time to tumor progression. There was no difference in local or marginal recurrence with increasing light dose. Recurrent anaplastic astrocytomas tend to do better than recurrent glioblastomas with PDT.

Interstitial photodynamic therapy of nonresectable malignant glioma recurrences using 5‐aminolevulinic acid induced protoporphyrin IX

“…This treatment modality is referred to as interstitial photodynamic therapy (iPDT). Its feasibility and effectiveness has been investigated in brain tumor models [11,12] and in first clinical applications with Photofrin [13][14][15][16]. Unfortunately, prolonged skin sensitization and damage to normal brain tissue due to the limited selectivity of the applied PS (Photofrin or Photofrin II) have obstructed the broad application of this potentially minimal invasive treatment concept.…”

A systematic review of photodynamic therapy in the treatment of pre-cancerous skin conditions, Barrett’s oesophagus and cancers of the biliary tract, brain, head and neck, lung, oesophagus and skin

“…Five patients had postoperative permanent neurological defects (two in the medium-dose group and three in the highdose group). 138 In the repetitive ALA-PDT trial, the PDT group survived significantly longer than the surgery group (52.8 weeks vs 24.2 weeks), and had a significantly longer time to tumour recurrence (8.6 months vs 4.8 months). Three patients had deep vein thrombosis, two of which were in the PDT group.…”

“…138,139 Both trials recruited fewer than 30 patients, and both were reported as full papers. The treatments for the trial by Krishnamurthy et al 138 were Ps-PDT (at 630 nm) with three different light dose ranges, in patients with recurrent or residual tumours ≤ 5 cm in diameter.…”

Atorvastatin reduces functional deficits caused by photodynamic therapy in rats

“…PDT damages the brain tissue and normal brain cells such as astrocytes and endothelial cells, and induces significant functional deficits in normal rats. The destruction of both tumor and normal surrounding tissue by PDT is dependent on the laser optical and the photosensitizer doses (26)(27)(28). Complete tumor elimination requires an increase in PDT intensity.…”