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Photodynamic Therapy (PDT)

Also called:

  • photoradiation therapy
  • phototherapy
  • photochemotherapy

Photodynamic therapy (PDT) destroys cancer cells by using a drug called a photosensitizer, which makes the cells sensitive to laser light. PDT is a fairly new procedure and was approved for use in Canada in the 1990s. It is used:

  • to treat tumours in the lining of some organs
  • to relieve blockages caused by tumours in the esophagus or lungs

PDT is usually done in stages:

  • the photosensitizer is given and is absorbed by all body cells but stays in cancer cells longer than in normal cells
  • after a period of time, the cancer cells are exposed to a low intensity laser light
    • the photosensitizer absorbs the light and a chemical reaction occurs that kills the cancer cells while sparing most normal cells

A range of tests may be done before PDT, depending on the area being treated. Preparations similar to endoscopic procedures or conventional surgery may be needed. The photosensitizer makes the skin and eyes sensitive to strong indoor or outdoor light (photosensitive) for 4 to 6 weeks or more after treatment, so special precautions need to be taken.

PDT may be used with other cancer treatments such as surgery, chemotherapy or radiation therapy. Tumours that regrow and start to cause problems again can be retreated with PDT.


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