Learning About Photodynamic Therapy

Photodynamic therapy (PDT) treats cancerous cells with light. It uses light and medicines called photosensitizers to target harmful cells. PDT was first approved by the U.S. Food and Drug Administration to treat actinic keratosis (AK) of the face and scalp. AK causes precancerous lesions on the skin. This happens from sun damage.

PDT is now approved to treat:

• Advanced cutaneous T-cell lymphoma.
• Barrett's esophagus.
• Basal cell skin cancer.
• Esophageal (throat) cancer.
• Non-small cell lung cancer.
• Squamous cell skin cancer (Stage 0).

PDT is less invasive than other cancer treatments. It causes very little damage to healthy cells. It usually causes little or no scarring after the treatment area heals. The treatment can be done in the doctor's office. It can be used with other cancer medicines and treatments. In some cases, it is better than surgery. This is because it allows doctors to treat a larger area than surgery. It also allows doctors to treat hard-to-reach areas like the nose and eyelids.

You're given a photosensitizing drug. These medicines can be a gel or a liquid. They can also be taken through an intravenous (I.V.) line in a vein. Then a doctor exposes the skin to light. The light can come from a laser. It can also come from a bulb with a specific wavelength of light.

When skin is exposed to light, an oxygen molecule is created. It kills harmful cells. The molecule also damages blood vessels. After this reaction, the immune system works harder. Sometimes PDT is used to treat internal tumors. These can be in the lungs, throat, and airways. The doctor inserts a thin flexible tube down the esophagus. The tube (an endoscope) has a camera at the end. A fiber optic cable is threaded through the endoscope. The cable casts light onto the harmful cells.

PDT works very well on early-stage tumors. It can also prolong life for people who have cancers that can't be operated on. PDT can improve quality of life. It works very well to treat AK. It can also clear basal cell carcinoma lesions.

PDT can cause:

• Temporary sensitivity to sunlight and bright lights. This causes redness and a tingling or burning feeling on the skin where the medicine is applied.
• Burns, swelling, pain, and scarring in the treatment area.
• Depending on the treatment area, it can also cause:
  • A cough.
  • Trouble swallowing.
  • Stomach pain.
  • Pain when breathing.
  • Shortness of breath.
  • Skin irritation (redness, stinging, swelling, or itching).

PDT can harm normal cells in the treatment area. It can only reach cells on the surface of the skin or organs. PDT can't reach tumors that are too large or deep.

PDT is promising because fewer new cancer drugs are being approved. It's an effective and safe tool for oncology. Researchers are looking for ways to expand its use. They are looking at ways to make light go deeper into tissues.