Photodynamic therapy (PDT) is a light-based treatment for certain skin cancers (superficial basal cell carcinoma and Bowen’s disease), precancerous skin lesions due to chronic sun damage (actinic keratosis) and selected skin conditions such as viral warts and acne vulgaris. This treatment involves the application of a special light-sensitive cream to the affected area where it is taken up by the abnormal cells. The cream is left in place for about 3 hours, following which red light is shone on the treatment area to activate a chemical to kill the abnormal cells.
Removing scales and crust
Application of light-sensitive cream
Covering with opaque Dressing
Shining with red light
On the day of treatment, your doctor will first clear the treatment area of any overlying scales or crust, followed by application of the light-sensitive cream. The cream will be kept in place with an opaque dressing and you will be asked to return to the phototherapy clinic approximately 3 hours after the application. There, the dressing and excess cream will be removed and red light will be shone on the treatment area for between 8 to 20 minutes. In most cases, the same treatment needs to be repeated 1 to 2 weeks later.
During the light treatment, you may experience some burning discomfort where the light is shone, which is mostly tolerable. If necessary, a cold water spray will be administered by the nurse to reduce the discomfort. In cases where pain continues to be an issue, a local anaesthesia injection can be given to numb the treatment area.
Pain and itch may persist following the treatment and this is usually worse in the first 2 days following treatment. The treated area may be reddish or may ulcerate but it rarely leaves a disfiguring scar. A scab may form which usually drops off on its own after a week. Some pigmentation may occur posthealing but this will gradually settle with time. If 2 treatments are unsuccessful, re-treatment may be considered 3 months later.
You should keep the treatment site covered to avoid sun exposure for 48 hours post-treatment. If a scab forms, be careful not to scratch or peel it off so as not to disrupt the natural healing process. If appropriate, your doctor may prescribe an antiseptic gel to reduce the risk of skin infection at the treated area.