Local eradication of rat colon cancer with photodynamic therapy: correlation of distribution of photosensitiser with biological effects in normal and tumour tissue
Article Abstract:
Photodynamic therapy is a method of treating cancer in which a photosensitizing agent (a compound which, when exposed to light, becomes toxic to cells) is administered. The area of the tumor is then exposed to laser energy, producing tissue destruction that is proportional to the photosensitizer concentration and laser strength. Although it was originally claimed that cancer cells have a much higher affinity for photosensitizing compounds than normal cells, it now appears that they accumulate only about twice as much of the incipient cytotoxin as normal cells, with different photosensitizer compounds displaying different affinities. To investigate the tissue distribution of aluminum sulphonated pthalocyanine (AlSPc) and colonic recovery from tumor destruction, a rat model of colon cancer (dimethylhydrazine-induced tumors) was used. Forty-eight hours after intravenous injection of AlSPc, tumors contained about twice as much photosensitizer as normal colonic mucosa. Microscopic analysis revealed that the tissue supporting the tumor had the majority of excess AlSPc, whereas the tumor itself contained about the same amount as normal tissue. Following exposure to light from an argon pumped dye laser, there was a sharp demarcation between necrotic (destroyed) areas (both tumor and normal tissue) and adjacent tissue; healing in both regions occurred by regeneration of normal tissue. The maximum depth of tissue destruction using this method was only several millimeters, indicating that this method alone would mostly likely be ineffective for large colonic tumors. However, the technique holds promise for the eradication of small tumors or small groups of tumors that may remain or recur after conventional surgical therapy. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Gut
Subject: Health
ISSN: 0017-5749
Year: 1991
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Monitoring photodynamic therapy of solid tumors online by BOLD-contrast MRI
Article Abstract:
This article describes the use of blood oxygenation level-dependent (BOLD) contrast magnetic resonance imaging for real-time monitoring of photodynamic therapy. Data indicate that the technique may have applications in intraoperative situations as well.
Publication Name: Nature Medicine
Subject: Health
ISSN: 1078-8956
Year: 2003
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