Photodynamic therapy (PDT), also called photoradiation therapy, phototherapy, and photochemotherapy, has existed for about 100 years and is a type of cancer treatment that uses light to kill abnormal cells. A special drug called a photosensitizer or photosensitizing agent is circulated through the bloodstream.
After the agent has been absorbed by the cancer, usually over a period of a few hours to a few days, the tumor is exposed to a special kind of light which together with the agent destroys cancer cells. PDT is thought to potentially also destroy tumor-feeding blood vessels and stimulate the immune system to attack the cancer cells.
PDT is currently approved by the Food and Drug Administration to treat or relieve the symptoms of esophageal cancer and the most common form of lung cancer, called non-small cell lung cancer. A handful of photosensitizers are approved; the best one for each patient depends on their specific diagnosis.
PDT is a promising treatment for certain types of tumors because in some cases, it can cure cancer. It is also:
- Less invasive and quicker than surgery and other procedures
- Leaves little to no scarring and has no long-term side effects
- Can be targeted very precisely to cancerous cells
- Can be repeated many times at the same site
Treatment can make the eyes and skin especially sensitive to light for about six weeks. During this time, patients should avoid direct sunlight and bright indoor light. Because the basis of phototherapy is light, its treatment is limited to areas on or just below the skin. Newer, more sophisticated photosensitizing methods are in development.
Side effects are rare, but may include:
- Burning, swelling, or pain on or below the skin's surface
- Trouble swallowing
- Painful breathing
- Shortness of breath
How to Prepare for PDT
It is important to follow any physician instructions to prepare for surgery.
What to Expect During PDT
Each session of PDT is relatively simple. Patients receive either a photosensitizer drug and wait until it has concentrated in the tumor, or they may have the drug administered and return days later for phototreatment. Phototreatment takes place on an exam table, and the patient receives local or general medicines for pain control and relaxation. The appropriate type of light is activated over the tumor in a strong, targeted beam. The procedure lasts as little as a few minutes, and up to two hours.
Recovery from PDT
Recovery from PDT is typically quite easy. Patients may experience some dryness or mild burning on the skin, but other effects are uncommon. Gentle skin products such as Vaseline can be helpful. Avoid the sun, as light sensitivity is increased for a time following PDT; even a few minutes of sun exposure can sometimes cause discomfort. Please follow any doctor's instructions regarding medications and physical activity, but most patients are able to return to normal activities right away.