overview
Metvix® is a topical therapy for pre-cancerous and skin cancer lesions such as actinic keratoses, basal cell carcinomas and Bowen's disease.
It starts with a topical application of Metvix® which results in the selective accumulation of photoactive molecules in the neoplastic tissue.
Following the Metvix cream being applied, it must penetrate and be absorbed over time – typically three hours.
The final step: photodynamic therapy (PDT). Exposure to red light in the presence of oxygen generates a reactive oxygen process which kill the targeted neoplastic cells. Healthy surrounding tissue is spared.
PHOTODYNAMIC THERAPY (PDT): A NEW TREATMENT FOR SKIN CANCER
PDT uses light sources combined with a light-sensitive drug (sometimes called a photosensitising agent) to destroy cancer cells. PDT is particularly suitable in areas where the cancer develops in skin directly overlying bone, such as Bowen’s disease on the shins and hands.
Before your treatment the doctor/nurse may remove any scabs from the area. A photosensitising cream (for example, Metvix®, which contains methyl aminolevulinate) will then be applied to your skin. It will be left on for a specific time period, usually between 3–6 hours, depending on the type of cream that is used. This is so that it can penetrate into the skin.
After the cream is removed, the doctor shines a special light onto the treatment area. The light treatment usually lasts somewhere between 8–45 minutes depending on the light source used.
Afterwards a dressing is put on to cover the area and protect it from light. You may need to keep the dressing on the treated area for up to 36 hours after your treatment. You will be given instructions about this before you leave the clinic.
Usually only one treatment of PDT is needed, but occasionally two or three further treatments may be given if your skin cancer is thick. Your doctor or nurse will be able to give you more detailed information about your specific PDT treatment.
Video illustrating the mechanism of action...
Side effects of PDT for skin cancer
Pain: Before your PDT treatment, your doctor or specialist nurse may advise you to take a couple of paracetamol tablets to prevent any possible pain. For many people this is all they need, but occasionally a local anaesthetic is given before treatment.
At the end of treatment a steroid cream may be applied to the treated area to stop it becoming painful. When you go home you may be given steroid cream to use if the area becomes painful.
Sensitivity to light: The treated area of skin will be sensitive to daylight and bright, indoor lighting. This effect will probably last for about 24 hours. You will need to keep the treated area of skin covered during this time to avoid the skin becoming burnt. After that you can wash, bathe or shower as usual, but you will still need to treat your skin gently and not rub the area until it has healed.
Healing
After PDT, a crust may form over the treated area. The crust will fall off naturally in a few weeks, leaving the healed new skin underneath. Usually there is no scarring and the appearance of the healed skin is very good.