Photodynamic therapy uses a light-sensitive drug that is activated inside the body by laser light to kill cells, usually cancer cells. First, you receive a special drug — typically by injection — that is absorbed by cancer cells. One to three days later, your doctor applies a laser light to the targeted areas, which causes cancer cells to be killed by reacting with oxygen. Photodynamic therapy also appears to damage blood vessels in tumors and to activate the immune system to attack cancer cells.

For surface tumors such as skin cancer, your doctor may put a drug on the skin and use light-emitting diodes (LEDs) instead of lasers.

Photodynamic therapy treatments may be repeated. This therapy can be used alone or in combination with other treatments, such as surgery, chemotherapy or radiation therapy.


In photodynamic therapy, the combination of the laser and the drug causes a chemical reaction that destroys the targeted cells. This is a two-part treatment:

  1. First, the doctor applies the light-sensitive drug (photosensitizer). For internal conditions, such as esophageal or lung cancer, the drug is injected into your vein. The drug is absorbed into your body, especially by fast-growing cancer cells.
  2. One to three days later, the doctor inserts a thin, lighted, flexible tube (endoscope) into the area that needs treatment — for instance, your esophagus (the muscular passageway that runs from your throat to your stomach) or your lungs. Through the endoscope, the doctor shines a high-powered laser light (different from radiation therapy or heat-producing lasers) onto the diseased tissue to activate the drug.

Photodynamic therapy is used to treat conditions such as:

Side effects can occur with photodynamic therapy, including:

  • Sensitivity to light, which means you'll need to avoid any bright light, including the sun, for several weeks to prevent sunburn, redness and swelling.
  • Swelling and inflammation around the site being treated, and other signs and symptoms, depending on the treatment site, such as pain or trouble swallowing or breathing from treatment of the esophagus.
Jun. 16, 2011