Photodynamic therapy (PDT) is a treatment that uses special drugs, called photosensitizing agents, along with light to kill cancer cells. The drugs only work after they have been activated or "turned on" by certain kinds of light. PDT may also be called photoradiation therapy, phototherapy, or photochemotherapy.
Over a certain amount of time the drug is absorbed by the cancer cells. Then light is applied to the area to be treated. The light causes the drug to react with oxygen, which forms a chemical that kills the cells. PDT might also help by destroying the blood vessels that feed the cancer cells and by alerting the immune system to attack the cancer.
The period of time between when the drug is given and when the light is applied is called the drug-to-light interval. It can be anywhere from a couple of hours to a couple of days, depending on the drug used.
The 2-part treatment offers the following conveniences:
- No prescription to fill
- No daily medication to remember
- Treatment is administered by a qualified healthcare professional
Studies have shown that PDT can work as well as surgery or radiation therapy in treating certain kinds of cancers and pre-cancers. It has some advantages, such as:
- It has no long-term side effects when used properly.
- It's less invasive than surgery.
- It usually takes only a short time and is most often done as an outpatient.
- It can be targeted very precisely.
- Unlike radiation, PDT can be repeated many times at the same site if needed.
- There's usually little or no scarring after the site heals.
- It often costs less than other cancer treatments.
But PDT has it's limits, too:
PDT can only treat areas where light can reach. This means it's mainly used to treat problems on or just under the skin. Because light can't travel very far through body tissues, PDT can't be used to treat large cancers or cancers that have grown deeply into the skin or other organs.
PDT can't be used to treat cancers that have spread to many places.
The drugs used for PDT leave people very sensitive to light for some time, so special precautions must be taken after the drugs are put in or on the body.
PDT can be used in people with certain types of cancer to help them live longer and improve their quality of life. It's becoming more widely recognized as a valuable treatment option for localized cancers (cancers that have not spread far from where they started).
PDT is also used to treat pre-cancers of the skin, and is being tested against pre-cancers in the mouth and other places.
Several photosensitizing agents are currently approved by the US Food and Drug Administration (FDA) to treat certain cancers or pre-cancers.
A solution is put right on the spots (called lesions) of actinic keratosis. This means the lesions are sensitive to the light but the rest of the body is not.
Topical Solution is applied to the AK. The solution is then absorbed by the AK cells where it is converted to a chemical that makes the cells extremely sensitive to light. When the AK cells are exposed to the Light Illuminator, a reaction occurs which destroys the AK cells.
Photosensitivity reactions: Reactions caused by light can show up on the skin where the drug is applied. They usually involve redness and a tingling or burning sensation. For about 2 days after the drug is used, you should take care to not expose treated areas of your face and scalp to light.
- Stay out of strong, direct light.
- Stay indoors as much as possible.
- Wear protective clothing and wide-brimmed hats to avoid sunlight when outdoors.
- Avoid beaches, snow, light colored concrete, or other surfaces where strong light may be reflected.
- Sunscreens will not protect the skin from photosensitivity reactions.
Skin changes: The treated skin will likely turn red and may swell after treatment. This usually peaks about a day after treatment and gets better within a week. It should be gone about 4 weeks after treatment. The skin may also be itchy or change color after treatment.
Our staff is always available for your questions and concerns about what you should expect your treated skin to look and feel like. We will advise you on what side effects should be reported and how best to reach our office.