PDT has been used in cancers to lengthen survival and improve quality of life. Though PDT is effective, causes no long-term problems, and was first used to treat cancer over 100 years ago, it is not widely used to treat cancer today. Still, it is offered in certain treatment centers and is becoming more widely recognized as a valuable treatment option for localized cancers. Three photosensitizing agents are currently approved by the United States Food and Drug Administration (FDA) to treat certain cancers or precancerous conditions.

Porfimer sodium (Photofrin^®)

Porfimer sodium is the most widely used and studied photosensitizer. It is combined with light from a laser to treat patients with:

• cancer of the esophagus
  • to relieve symptoms that are caused by a tumor totally blocking the esophagus
  • to relieve symptoms that are caused by a tumor partially blocking the esophagus and that can’t be treated with laser therapy

• Barrett’s esophagus, a condition that may lead to esophageal cancer in patients who don’t have surgery

• a type of non-small cell lung cancer that is endobronchial (affecting the lining of the bronchi) and microinvasive (has minimal spread of cancer cells) in patients who can’t have other types of treatment such as surgery or radiation therapy. PDT can be used to shrink tumors that are blocking the airway. This allows patients to breathe easier.

Aminolevulinic acid (ALA or Levulan^®)

Aminolevulinic acid is a drug applied directly to the skin. It is used to treat actinic keratosis (AK), a skin condition that can become cancer. It is approved for use only on the face or scalp. A special blue light is used rather than light from a laser.

Methyl Ester of ALA (Metvixia^®)

Methyl ester of ALA is one of several other forms of ALA that have been developed. A disadvantage of ALA is that it does not get into the cancer cells very easily. Newer ester forms, such as this one, do. It was approved by the FDA in July 2004 for treatment of non-hyperkeratotic actinic keratoses of the face and scalp. It is activated with a red light.

Meso-tetra-hydroxyphenyl-chlorin (mTHPC, temoporfin, or Foscan^®)

Temoporfin is not approved for use in the United States, but in 2001 was approved in Europe to ease some of the problems caused by head and neck cancer. It is a very active photosensitizer and requires a much lower dose of both the drug and light than does porfimer sodium. It is given up to 4 days before light is used to activate it.

Verteporfin (Visudyne^®)

Verteporfin has been developed and used to treat age-related macular degeneration, a progressive eye problem that leads to blindness. While it is a PDT, it is not used in cancer treatment and is not discussed in detail here.

Researchers continue to look for new photodynamic therapy drugs and many are being studied in clinical trials. Photodynamic therapy is now being tested for use against several other types of cancer, too. See the section, "The Future of Photodynamic Therapy."

Revised: 03/20/2007