Methyl aminolaevulinate-photodynamic therapy for actinic keratoses, squamous cell carcinoma in situ and superficial basal cell carcinoma employing a square wave intense pulsed light device for photoactivation.

摘要

Sir, Methyl aminolaevulinate (MAL) (Metvix~R cream MAL; Galderma, Watford, Herts, U.K.) is licensed for the treatment of basal cell carcinoma (BCC), actinic keratosis (AK) and squamous cell carcinoma in situ (Bowen disease) utilizing photodynamic therapy (PDT). It is a simple noninvasive procedure that offers patients at least equal efficacy and a high level of satisfaction and cosmetic outcome compared with cryotherapy and topical treatments. It may be used in patients who are poor surgical candidates, have large or multiple lesions, and where wounds would probably heal poorly or are in cosmetically sensitive areas. Metvix ~R cream has to be applied for 3 h under occlusion prior to photoactivation. The treatment itself takes between 7 and 9 min per treatment area when using the standard red light source (Aktilite~R Photocure ASA, Oslo, Norway). A 2-g tube of cream will treat an area of up to 20 cm~2. It is painful during treatment, particularly over bony areas. Much time and effort, and unnecessary anxiety and distress are loaded on to the patient and practitioner because of the pain this treatment can cause. Distraction therapy, nitrous oxide gas inhalation, sedation and cold chillers have all been employed to help minimize the pain. Local anaesthetic creams or injections cause vasoconstric-tion of the blood supply to the treatment area and appear to hamper efficacy.