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What is Photodynamic Therapy?

Sandra Koehler
Sandra Koehler

Photodynamic therapy, also known as blue light therapy, is a type of treatment used for some forms of cancer. It is also approved in the treatment of wet macular degeneration, a cause of vision loss in the aging population. Researchers are looking to expand the use of photodynamic therapy to include the treatment of psoriasis.

Photodynamic therapy is a US Food and Drug Administration, or FDA-approved treatment option used for esophageal cancer, and its precancerous lesions known as Barrett’s esophagus, and non-small cell lung cancer. Some dermatologists also utilize this technique for the treatment of hard-to-treat, treatment-resistant acne problems.

Treatment-resistant acne might respond to photodynamic therapy.
Treatment-resistant acne might respond to photodynamic therapy.

Currently, photodynamic therapy is in clinical trials for the treatment of more forms of cancer. Included in these trials are the skin and brain, the cervix and prostate, and the peritoneal cavity. The peritoneal cavity is located in the abdomen and encases the liver, stomach and intestines.

Photodynamic therapy uses three key components: a photosensitizer or a photosensitizer agent, a light and tissue oxygen. A photosensitizer is a specialized drug that gets absorbed by cancer cells. When this drug is exposed to a specific wavelength of light, determined by the location of the cancer, it becomes activated. This produces a form of oxygen which can kill the cancerous cells.

Since the drug used for photodynamic therapy remains in cancerous cells longer than healthy cells, this therapy option can do more than just kill cancer cells. It can cut off the blood supply and shrink or destroy tumors, or it can activate the immune system to allow the body to actively attack the cancerous cells.

The limitations of photodynamic therapy are conditional upon the size and location of the tumor or cancerous growth. Since light has to penetrate the skin and reach the location, it is not effective on deep organs and on larger tumors. It is also not an effective option for treating cancer that has metastasized or spread throughout the body.

Since the photosensitizer agents cause sensitivity to light in general, one side effect of this treatment option is eye and skin sensitivity to light, especially bright indoor lighting and sunlight, for up to six weeks after treatment. Other side effects of photodynamic therapy can include minimal damage or scarring to healthy tissue surrounding the cancerous cells, and swelling, burning and pain in the location being treated. Patients may also experience things like shortness of breath or painful breathing, coughing or trouble swallowing, or pain in the stomach, depending on the location treated.

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    • Treatment-resistant acne might respond to photodynamic therapy.
      By: Ocskay Bence
      Treatment-resistant acne might respond to photodynamic therapy.