Photodynamic therapy (PDT) is a method that is generally used when an esophageal cancer has been found very early, for example in a biopsy from a Barrett esophagus, or has come back after other treatment. PDT begins with the injection of a nontoxic chemical into the blood. This chemical is allowed to collect in the tumor for a few days. A special type of laser light is then focused on the cancer through an endoscope. This light causes changes in the chemical that has collected inside the cancer cells. The light changes the nontoxic chemical into a new chemical that can kill cancer cells.

The advantage of PDT is that it can kill cancer cells with very little harm to normal cells. One drawback is that the chemical must be activated by light, so only cancers near the inner surface of the esophagus (that can be reached by shining a special light through the endoscope) can be treated in this way. This light cannot reach cancers that have spread deeper into the esophagus or to other organs.

Side effects of PDT include redness or discoloration of the skin and sensitivity to the sun or to other light sources. These side effects can last for up to 6 weeks after therapy and, in some cases, may be severe. Because of this, patients are usually confined indoors for 6 weeks.

In preliminary studies, this treatment has cured some very early esophageal cancers that have not spread to deeper tissues. However, the length of follow-up time in these studies was short. If PDT is being used with the intent of curing a cancer, doctors should be certain that the cancer has not spread deeper, since the light used in PDT may only reach those cancer cells near the surface of the esophagus. Right now, PDT is being used to treat Barrett esophagus and very early esophageal cancers found in Barrett esophagus.

The major use of PDT is palliative treatment of advanced cancers that are blocking the esophagus and have come back after radiation therapy. In this situation, PDT does not destroy all of the cancer, but it kills enough of the cancer to improve the patient's ability to swallow. The exact role of PDT in the treatment of esophageal cancer is currently being evaluated in studies that compare results of PDT with other treatments, such as surgery or use of lasers to vaporize the cancer. Researchers are also working to improve PDT by developing new photosensitizing drugs and evaluating new ways of delivering the proper amount of light to the cancer.

Revised: 08/04/2006