A treatment for cancer that has definitely shown some promise in the last several years, photodynamic therapy (PDT) uses light and drugs known as photosensitizing agents to kill cancer cells and stop cancer from spreading. A novel treatment that causes far fewer side effects than some traditional cancer therapies, photo-dynamic therapy is currently being used to treat some skin cancers, esophageal cancer, non-small cell lung cancers, and mesothelioma. While still in a somewhat experimental stage, doctors have found PDT to help alleviate symptoms and improve quality of life for those diagnosed with mesothelioma cancer.
How Does it Work?
A photosensitizing agent is a chemical that, when exposed to light of a certain kind and wavelength, produces a type of oxygen that kills the cancer cells in that area. It can also aid cancer patients in that it can damage the blood vessels that feed the tumor, thus stopping its growth. There is also speculation that PDT can help activate the immune system.
Currently, several photosensitizing agents have been approved for use by the U.S. Food and Drug Administration. Administering one of these agents is the first step in a two-step treatment process using photodynamic therapy. Initially, the patient comes to an outpatient treatment area and receives the drug via injection into the bloodstream. All the body's cells absorb this agent but it remains in cancer cells longer than healthy cells. The next step involves a repeat visit to the doctor's office or cancer clinic. This time, the person administering the treatment exposes the tumor to a laser light, usually attached to a thin fiber optic glass strand which can be inserted near the tumor. The light is applied for 5 to 45 minutes, depending on the doctor's goals and the size or location of the tumor. Any dead tissue that results is removed about 4-5 days later by means of endoscopy.
Side effects of PDT include some discomfort at the treatment site, including swelling or bruising, and the patient may suffer sensitivity to light for the first 30 days after treatment. That means they should avoid exposure to direct sunlight, keep their body covered when outside, and keep indoor lights subdued until the reaction has ceased.
What are the Results?
While photodynamic therapy is not yet used as a sole source of treatment for those diagnosed with cancer, it has indeed produced some positive results. Currently, researchers are trying to discover PDT drugs that can better target specific cancer cells and photosensitizing agents to treat tumors that are buried deeper under the skin.
Author: Linda Molinari
Editor in Chief, Mesothelioma Cancer AllianceRead about Linda
Reviewer: Annette Charlevois
Patient Support CoordinatorRead about Annette