Photodynamic Therapy

Overview

Photodynamic therapy (PDT) is a treatment that uses a photosensitizing drug and red laser light to kill cells, usually cancer cells.

It is a two-part treatment. First, the drug is administered intravenously. The drug is absorbed especially by fast-growing cells. Two days later, an endoscope is inserted into the body and through it, the doctor shines a specific kind of laser light (different from radiation therapy or heat-producing lasers) onto the diseased tissue. The combination of the laser and the drug causes a chemical reaction that destroys the targeted cells.

PDT can be repeated without harming normal body tissues and can be used alone or in conjunction with other treatments, such as chemotherapy or radiation therapy.

Uses of Photodynamic Therapy

Photodynamic therapy is used to treat the following conditions:

• Barrett's esophagus
• Early esophageal cancer (adenocarcinoma or squamous cell carcinoma)
• Obstructing esophageal cancer (often used in place of, or in conjunction with, chemotherapy or radiation therapy)
• Persistent or recurrent esophageal cancer after surgery, chemotherapy or radiation therapy
• Gastric cancer
• Lung cancer
• Macular degeneration (destroys abnormal blood vessels)

Side Effects

Two major side effects are associated with photodynamic therapy:

• Local swelling and inflammation occur in and around the esophagus, which may cause chest discomfort, along with nausea, fever and constipation. These symptoms are usually controlled with the limited use of pain relievers and other medications.
• Photosensitivity (sensitivity of body tissues to light) always occurs after PDT and lasts for about four weeks. From the moment a patient is injected with a photosensitizing drug, the skin and eyes will be very sensitive to bright light. Exposure to bright light or direct sunlight must be carefully avoided to prevent sunburn, redness and swelling. Photosensitivity reactions can occur in minutes, so it is important to take precautions to shield the skin and eyes from intense light exposure.