Daylight photodynamic therapy (PDT) is a non-invasive treatment for pre-cancerous skin lesions such as actinic keratoses. Chemical sunscreen and a photosensitising cream are applied to the affected areas and patients remain outdoors for 2 hours. Crusting and redness of treated lesions are expected and resolve over 1-2 weeks, revealing smoother, healthier skin.
What is daylight photodynamic therapy (PDT)?
Photodynamic therapy involves the application of a light-sensitive (photosensitiser) cream to the affected area of your skin. The photosensitiser is activated when exposed to specific wavelengths of light. A chemical reaction takes place depriving the affected tissue of oxygen and this ultimately causes the destruction of abnormal skin cells. Over time the damaged tissue crusts and sheds along with the skin’s natural turnover cycle.
Daylight PDT can be used to treat general photodamage and actinic (solar) keratosis. Actinic keratoses are dry scaly patches of skin that are caused by long-term sun exposure. The patches are considered pre-cancerous and while most do not go on to develop into skin cancer, treatment is generally advised.
Your PDT appointment – what to expect
Before the treatment, we will check there is ample sunlight to allow for proper activation of the photosensitiser. The typical months for treatment are March-October in London.
The first step is to cleanse the skin followed by the application of a chemical sunscreen to the treatment area and any other areas that will be exposed to sunlight.
The next step is to prepare your skin. Your skin will be cleansed again and any scale or crusts are gently removed. The photosensitising cream will be applied to the area of your skin to be treated and left uncovered. You will then be asked to remain outside in natural daylight for two consecutive hours. This exposure to ultraviolet light activates the cream and the damaged cells start to be destroyed. Even on a dull, cloudy day or overcast day, there is typically enough daylight for the treatment to be effective. After two hours, you can cleanse the treated area at home.
Your daylight PDT appointment – aftercare and downtime
It is important to protect the treated area in the days after photodynamic therapy. You will be given detailed instructions on how to care for your skin. Some patients find that the area may weep slightly and form a crust, this is normal. It is possible that the condition may reoccur or some lesions may persist after PDT. Dr. Alexis will discuss having further photodynamic therapy or an alternative treatment if needed.