Ann's NOTE: We have a big section on PDT for breast cancer (see Breast Cancer Issues).
TORONTO Apr 26 (Reuters Health) - Brain tumors may be the next target for photodynamic therapy (PDT), which combines drugs and light to treat cancer and other conditions.
At the 70th annual meeting of the American Association of Neurological Sciences here, Dr. Paul Muller, a neurosurgeon at the University of Toronto in Canada, presented results from a safety study of PDT for treating malignant brain tumors. The treatment is safe, Muller reported, and higher light doses appeared to extend survival.
But he did not report how much longer patients survived or whether there were other differences between the patients who got the higher dose and the lower dose. PDT is a two-step therapy that is already being used to treat head and neck cancers, especially esophageal cancers. The first step is to give the patient a light-activated drug such as photofrin, which tends to collect in tumors.
The drug makes the abnormal tissue particularly sensitive to light. The second step is to shine a laser light on the drug-saturated tumors for a brief period of time. There are several PDT drugs available, and each is activated by different wavelengths of light.
Among the 112 patients included in the study, 86 had a type of tumor called a glioma. Of these tumors, 66 were recurrent gliomas, 11 were glioblastomas multiforme, and 9 were malignant astrocytomas. The patients were each given photofrin 12 to 24 hours prior to surgery. ``It was done close to the operation so there would be an increased concentration of the drug at the tumor site,'' Muller said. Surgery was performed, and the tumors removed.
The cavity left by tumor removal was rinsed and cleaned to remove material that might interfere with the light, and then illuminated with a laser. Patients received two different light doses. The higher dose was more effective, and prolonged survival for some patients, Muller said. There was no difference in toxicity between the two light doses, he added. Five percent of patients suffered complications from the surgery and 3% died.
``PDT does appear to have an effect,'' and hopefully may prevent local recurrences, Muller concluded. He and his colleagues are currently conducting two additional studies of PDT, one that adds PDT to standard therapy for patients with newly diagnosed astrocytic brain tumors, and one that compares high-dose and low-dose therapy for treating patients with recurrent astrocytic tumors.
Mayo Clin Proc, 10/01
Cancer Res, 3/02
articles and studies
Vit D/A Differentiation Enhances PDT:Prostate Cells
Green Light KTP Laser Therapy
Patient Information Re Dr. Porter and PDT: Ireland
Source: Ralph Moss,
Cancer Res, 2/03
J Cancer Res, 4/03
LINK to Photodynamic Treatment Ctr.,
in Indianapolis. Treatment involves
absorption (under the tongue), by
patient, of XYTOS sensitizing agent
XyChloro. It attaches to cancer cells & passes through healthy cells.
XyChloro is then activated by
light & sound & process kills cancer
cells leaving healthy cells
Company press release, 11/06
Treatment ctr opens in Indianapolis
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