Topical Photodynamic Therapy (PDT)

Presenting the PDT equipment

Photodynamic therapy PDT is used to treat Bowen’s disease, which is a pre-cancerous condition of skin and some types of skin cancer called basal cell carcinoma. The treatment involves preparing the lesion by removing superficial scale and crusts and then applying a special cream that is taken up by the abnormal cells and sensitises them to red light. Three hours after the cream is applied an intense red light emitted by a special lamp is shone onto the prepared lesion and the abnormal cells are destroyed. The process is often accompanied by some discomfort but this is alleviated by using the ‘super cooler’ to blow cold air onto the area of skin being treated to relieve any burning sensation.

There are a number of different methods by which basal cell carcinomata and Bowen’s disease can be treated, including surgical excision or curettage and cautery, both of which require local anaesthetic, cryotherapy using liquid nitrogen, radiotherapy, some cytotoxic creams and more recently topical PDT. The advantages of PDT are that it does not require anaesthetic, and the skin heals with little or no scarring. It is particularly useful in treating lesions on sites of the body that do not heal well e.g. the lower leg, in people with poor circulation or swelling. It is also useful in treating lesions that would leave a large area of scarring or would require a skin graft if removed surgically.

Since starting the PDT service we have treated 60 basal cell carcinomata and areas of Bowen’s disease with some excellent results. Now that the Wessex Cancer Trust Clinical Nurse Specialists in skin cancer have been trained in PDT, the plan is to start a nurse led PDT treatment clinic that will increase our capacity and enable us to treat more patients.

Patients who have a lesion that might be a basal cell carcinoma or Bowen’s disease, in most cases, need to have a skin biopsy to establish the diagnosis. The most appropriate treatment choice will then be discussed with them by their dermatologist taking into account many different factors including the precise type of lesion as seen under the microscope, the size and site of the lesion and the number of lesions that need to be treated (some people have several). People with more than one lesion may have them treated by different methods to ensure optimum results.

The Dermatology department, with the equipment for PDT and the skills of the plastic surgeon, will be able to provide Moh’s surgery (a particular type of surgical excision to remove all the basal cell carcinoma with the minimum of normal skin being removed). So, now, patients who attend with Bowen’s disease and basal cell carcinoma can be given all the optimum treatments.

We are extremely grateful to the League of Friends and Wessex Cancer Trust who provided the funding for the light source and the super cooler for PDT respectively.

Deborah Mitchell, Consultant Dermatologist