Photodynamic Therapy for Pre-cancerous lesions of the skin Alan Milligan Clinical Nurse Specialist for Non-Melanoma Skin Cancers.

Conventional Photodynamic therapy and Day-Light Photodynamic Therapy A form of phototherapy involving light and a photosensitizing agent used to elicit cell death (photo-toxicity) Useful to treat pre-non-melanoma skin cancers such as: Actinic Keratosis Bowen’s Disease sBCC (superficial basal cell carcinoma) The lesion has to be thin – in the top layer of the skin so that the sensitizer can be absorbed fully and be accessible to the light field Most appropriate for single lesions but also in a new from (Day-Light PDT) also useful for ‘field-change’ where actinic damage is widespread and lesions may not be fully delineated.

Publications Guidelines for topical photodynamic therapy: report of a workshop of the British Photo- dermatology Group Dr S.H. Ibbotson et al Br J Dermatol 2002 Apr: 146 (4) Ambulatory photodynamic therapy: a new concept in delivering photodynamic therapy Dr S.H. Ibbotson et al Br J Dermatol 2006 Apr: 154 (4)

Actinic keratoses and risk NICE* estimates that over 23% of the UK population aged 60 and above have AK. Although the risk of an AK transforming into a squamous cell carcinoma (SCC) is very low, this risk increases over time and with larger numbers of lesions. The presence of ten AK is associated with a 14% risk of developing an SCC within five years. * Data form 2014

How it works PDT involves the use of a light-sensitive chemical (called a photo-sensitizer). This photo-sensitizer is, by itself, harmless. When light of a certain wavelength (usually red light) is shone onto a cancerous or pre-cancerous skin lesion to which the photo-sensitizer has been applied, the photo-sensitizer is activated. This causes changes in the oxygen molecules within the sun-damaged skin cells. The “excited” oxygen molecules will kill the cells. Only the area of skin exposed to the light source will be affected and become inflamed after the inflammation clears the lesion will be cured

Advantages Non- surgical Suitable for virtually all patients Treatment can be completed in half a day Minimal inflammatory response Visible assessment of response within weeks with good cosmetic outcome after 8-12 weeks Treatment can be repeated in the same area as required Disadvantages Sometimes ineffective for hyperkeratotic lesions Can be painful during brief light-treatment period, depending on site

The Practicalities (conventional PDT) The procedure is explained and the patient gives written consent The identified lesion(s) are prepared: if the lesion is hyperkeratotic the crust can be removed by gently scraping Apply the photo-sensitizer, covering the lesion entirely and up to 3 mm over its margin. The covering should be opaque Apply an occlusive dressing – such as Tegaderm™– to contain the photo-sensitizer whilst it is absorbed Cover with dressing Patient waits in clinic for 3 hours whilst photo-sensitizer is absorbed

After 3 hours dressing is removed and photo-sensitizer is wiped off At this stage anaesthetic can be administered if indicated The lesion is exposed to light for 8 minutes The area is then covered with a dressing for 24hrs as it will be light sensitive

Dealing with pain/discomfort During the light exposure the patient may feel pain or discomfort This is usually described as ‘burning’ or ‘stinging’ Generally pain/discomfort is dependent on the treatment site Scalps, shins, the face and ears tend to be painful areas to treat Cold water spray to the treated area during the light exposure Local anaesthetic using Lidocaine The pain/discomfort lasts only for the duration of the exposure

Daylight Photodynamic Therapy for NMSCs Dr. Sally Ibbotson Consultant Dermatologist Photobiology Unit Ninewells Hospital Dundee Studies using over 400 patients undergoing ambient treatment

The Practicalities (‘day-light’ PDT) Currently licensed for treatment of head and neck lesions only and form March - October The procedure is explained and the patient gives written consent Apply Factor 50+ sun protection to treatment area Remove any keratotic crust if present Apply photo-sensitizer thinly over the entire treatment area Patient then leaves clinic within 30 minutes and spends 2 hours outside in ambient light. NOT direct sunlight Patient can sit in a conservatory Patient then washes off photo-sensitizer and covers with dressing for the rest of the day Recommended review time 3 months to allow adequate time for complete healing

Day-Light PDT Advantages Suitable for areas of ‘field change’ Limited time spent in the clinic Treatment is completed in just over 2 hrs Not painful during exposure to light Disadvantages Not suitable for hyperkeratotic lesions May not be suitable for patients who are not self-caring

Alan Milligan CNS Non Melanoma Skin Cancer Royal Free Hospital – then page 1454 A primary contact for patients Work closely with Melanoma CNS and Oncology Member of Skin Cancer MDT Skin Cancer Clinics Teaching Clinical Trials Immunosuppressed Patients Clinic Skin surgery Photo-dynamic Therapy Audit