PRINCIPLE
PDT is a non-thermal light chemical reaction and need oxygen, photosensitive substance (photo-sensitizer) and laser simultaneously to participate in. Photo-sensitizer is absorbed by neoplasm tissue and accumulates in the cells for a long time. Photo-sensitizer is activated with the appropriate wavelength of light and reacts with oxygen to generate reactive single state oxygen and hotochemical substance that are toxic to cells leads to apoptosis and necrosis of cancer; PDT can result in local vascular lesion of tumor; PDT can make tumor tissue ischemic necrosis and initiate immune reaction of antitumor. Photo-sensitizer is exposed to laser light and subsequently reacts with oxygen, and gives rise to single state oxygen and toxic photochemical substance.
PROCEDURE
- Photosensitizer (Photofrin, porfimer sodium), 2mg/kg,is administrated intravenously 48 hours before scheduled light activation.
- Laser light irritation: 48 hours after photosensitizer administration, 630-nm red laser light is delivered through optic cables (thin fibers that transmit light) to deliver light to areas inside the body. The light used for PDT can come from a laser or other sources of light. The total light dose administered ranges from 20 to 30 J/cm2.The light irritation is often repeated 72 hours after photo-sensitizer administration.
- The delivery of laser fiber may be through endoscopes, such as gastrointestinal endoscope(for esophageal or gastric cancer) or bronchendoscope (for lung cancer) , or intraoperatively.
- PDT may also be repeated and may be used with other therapies, such as surgery, radiation, or chemotherapy.
INDICATION
Formally Approved
America
- Esophageal cancer (partically or completely obstructive)
- Redical treatment of early stage esophageal cancer
- Microinvasive non-small cell lung cancer, unable to be given surgery and radiotherapy
- Obstructingnon-small cell lung cancer
Europe
- Esophageal cancer and lung cancer
- Radical treatment of early stage lung cancer