Photodynamic Therapy Overview
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 applied 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 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.
PDT can cause some damage to nearby healthy tissue such as:
Other side effects of PDT are related to the treated area. They can include:
The side effects are usually temporary.
Some light sensitising drugs make the skin and eyes sensitive to light for approximately 6 weeks after treatment. So, you need to avoid direct sunlight and bright indoor light for at least 6 weeks. The skin gets very sensitive and may become very red and sore if it is exposed to light during this time.
Aminolevulinic acid (Levulan Kerastick) is a solution that’s put right on the spots (called lesions) of actinic keratosis. Unlike porfimer sodium, it does not reach other parts of the body. This means the lesions are sensitive to the light but the rest of the body is not.
The drug is left on the affected skin for about 14 to 18 hours, usually until the next day. At that time your doctor will expose the area being treated to a blue light for about 15 minutes. During the light therapy you and the doctor will wear protective eyewear. You may feel stinging or burning once the area is exposed to the blue light, but it should go away within a day or so. The treated area may get red and scale and crust for up to 4 weeks before healing. If a lesion does not completely go away after treatment, it can be treated again 8 weeks later.
Source: www.medicinenet.com / www.cancer.org