Photodynamic Therapy (PDT or Blue Light Therapy)
Gary W. Cole, MD, FAAD
Dr. Cole is board certified in dermatology. He obtained his BA degree in bacteriology, his MA degree in microbiology, and his MD at the University of California, Los Angeles. He trained in dermatology at the University of Oregon, where he completed his residency.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
- What is photodynamic therapy (PDT)?
- What photosensitizer drugs are available?
- What light sources are available, and how are they applied?
- How does photodynamic therapy work?
- Does PDT make me permanently more sensitive to light?
- How is PDT used to treat the skin?
- What is a typical skin PDT session like?
- How much improvement can I expect with photodynamic therapy?
- Where can I have photodynamic therapy, and who performs the procedure?
- What are the advantages with photodynamic therapy for treating actinic keratoses?
- Am I a good candidate for photodynamic therapy?
- What growths is PDT not good for?
- What are possible complications or side effects of photodynamic therapy?
- Is there scarring from photodynamic therapy?
- What are alternatives for photodynamic therapy?
- What about insurance coverage and costs of photodynamic therapy?
- How do I prepare for my procedure?
- How is recovery after photodynamic therapy (PDT)?
- Is there pain after PDT?
- How do I take care of my treatment area after photodynamic therapy?
- What is the chance that my actinic keratoses will recur?
- Find a local Dermatologist in your town
What is photodynamic therapy (PDT)?
Photodynamic therapy (PDT) is a medical treatment that utilizes a photosensitizing molecule (frequently a drug that becomes activated by light exposure) and a light source to activate the administered drug. Very thin superficial skin cancers called actinic keratoses and certain other types of cancer cells can be eliminated this way. Acne can also be treated as well. The procedure is easily performed in a physician's office or outpatient setting. PDT is also referred to as blue light therapy.
PDT essentially has three steps. First, a light-sensitizing liquid, cream, or intravenous drug (photosensitizer) is applied or administered. Occasionally, a photosensitizing molecule that is already part of the body can be activated. Second, there is an incubation period of minutes to days. Finally, the target tissue is then exposed to a specific wavelength of light that then activates the photosensitizing medication. The mechanism by which tissue is destroyed seems to depend on the presence of activated oxygen molecules.
- application of photosensitizer drug
- incubation period
- light activation
Although first used in the early 1900s, PDT in the modern sense is a new, evolving science. Current PDT involves a variety of incubation times for different the light-sensitizing drugs and a variety of light sources depending on the target tissue. The basic premise of PDT is selective tissue destruction.
At present, the primary limitation of available PDT technology for skin is the depth of penetration of the light and ability to target cells within 1/3 of an inch (approximately 1 cm) of the light source. Therefore, tumors or atypical growths must be close to the surface of the skin for PDT to work.
In oncology, PDT is FDA approved for non-small cell lung cancer, esophageal cancer, and precancerous changes of Barrett's esophagus. Its use is also being further investigated through clinical trials in general oncology for conditions including cancers of the cervix (mouth of uterus), prostate gland, brain, and peritoneal cavity (the abdominal space that contains the stomach, liver, and internal organs).
In dermatology, PDT with the photosensitizer Levulan Kerastick (20% delta-aminolevulinic acid HCl) is used for the treatment of very early, thin skin cancers called actinic keratoses (AK). The initial approval was specifically for the treatment of actinic keratosis of the face and scalp with application of the photosensitizer followed by a timed exposure to a special blue light source. PDT has also used for acne, rosacea, thin nonmelanoma skin cancers, sun damage, enlarged sebaceous glands, wrinkles, warts, hidradenitis suppurativa, psoriasis, and many other skin conditions. It is not used to remove moles or birthmarks.
Learn more about: Levulan Kerastick
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