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


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.
Krishnamurthy
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Section of Neurosurgery, Milton S Hershey Medical Center, Hershey, Pennsylvania 17033-0850, USA.
Powers
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SK
Witmer
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Brown
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D000328:Adult; D000368:Aged; D017323:Dihematoporphyrin Ether / Q000008:administration & dosage; D018572:Disease-Free Survival; D004307:Dose-Response Relationship, Radiation; D005910:Glioma / Q000188:drug therapy*; D006414:Hematoporphyrin Photoradiation / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D053685:Laser Therapy; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D010778:Photochemotherapy; D017319:Photosensitizing Agents; D013238:Stereotaxic Techniques; D015173:Supratentorial Neoplasms / Q000188:drug therapy*; D016019:Survival Analysis; D016896:Treatment Outcome
D017319:Photosensitizing Agents; D017323:Dihematoporphyrin Ether