Photodynamic Therapy (PDT) - Health Tips

Photodynamic Therapy (PDT) treats actinic keratoses (precancerous lesions), certain types of skin cancer, and acne.

PDT is a two-stage treatment combining light energy with a drug (photosensitizer) to destroy said cancerous and precancerous cells after light activation while leaving normal cells intact. The treatment consists of application of a sensitizing agent – either Levulan (aminolevulinic acid 20%) or Metvixia (methyl aminolevulinate 16.8%) – which is left on the skin and allowed to be absorbed by the abnormal tissue for approximately 1 to 2 hours, followed by exposure to intense light for 15 minutes.

The chemical photosensitizer is activated by specific wavelengths of light energy. When it is triggered, it becomes toxic to the targeted tissue, making them very sensitive to light, which destroys the malignant cells. So it is very precise and controlled, minimizing any effect on the surrounding tissues.

After a short healing period, new skin cells replace the abnormal cells. Studies show that this light-based therapy promotes the body’s immune response, helping it destroy cancerous and precancerous cells.

If you have any questions about skin cancer, diagnostic procedures or skin cancer treatments in Portland, please contact us to schedule a consultation. Knott Street Dermatology in Portland also meets the needs of patients from nearby Lake Oswego, West Linn, Beaverton and Clackamas.

Photodynamic therapy (PDT) treatment is FDA-approved for the treatment of actinic keratoses(AKs), which are rough, scaly precancerous patches of skin caused by chronic and excessive exposure to the sun.

The process is a 2-step treatment: Initially a liquid containing a chemical substance called amino levulinic acid (ALA) is applied to the areas to be treated and left in contact with your skin for one hour. ALA is a “photoreactive drug”, which means that it is transformed and becomes active when exposed to a very specific type of light – in this case, a blue light.  The ALA is absorbed exclusively by the diseased tissues while not affecting the surrounding healthy tissue. After the incubation period of one hour, we treat the areas with pulses on intense blue light using the Sciton BBL™ equipment with the 420nm filter.

Since the ALA is taken up by the rough areas of skin, this treatment also causes significant cosmetic improvement by giving you a much smother, more homogeneous appearing skin, therefore this is also a very good treatment for facial rejuvenation.

In addition to treating pre-cancer actinic keratoses and aging skin, this treatment can also be very effective for controlling inflammatory acne. This is done by killing the bacteria that are associated with the disease and by shrinking down the sebaceous glands, which re also associated with the development of acne.

Most patients will feel a stinging and burning sensation during treatment, and it can be as intense as a rubber band snapping on your skin, however this sensation usually improves immediately after treatment and resolves within 24 hours or less. Treated skin must be protected from light for 36 hours following the PDT procedure.