This study is a multicenter study investigating the clinical efficacy of repetitive daylight-PDT with MAL compared to cryosurgery in regard to prophylaxis and treatment of AKs in the face. Patients will be randomly allocated to treatment groups. 5 PDT treatment sessions (visits 1-5) will be performed within 18 months. In the control group, cryosurgery will be performed at visit 1, and in case of non-cleared or newly occurred AKs at visits 2-5.~Before application of the photosensitizer, an organic sunscreen (Actinica® lotion, LSF 50+) without mineral filters will be applied In the entire face.~After an absorption time of approximately 15 minutes and before applying MAL (Metvix®), the surface of the AK lesions will be prepared gently with a curette or a scalpel to remove scales and crusts and roughen the surface of the AK-lesions. This is to facilitate penetration of the cream and light to the AK lesions.~After lesion preparation, MAL (Metvix®) will be uniformly applied on the whole face in a thin layer.~Within 30 min after MAL application the patients go outside and expose themselves for 2 hours to daylight. Daylight-PDT can be performed from March until October, during non-rainy weather with an outdoor temperature of at least 10° Celsius. Daylight exposure must start at least 3 hours before sunset.~At the end of the exposure, residual photosensitizer is washed off and the patients spend the rest of the day indoors.~Cryosurgery of AK lesions will be investigated as standard reference therapy. Single freeze-thaw cryosurgery is performed using an open spraying procedure with liquid nitrogen with nozzle size C. After formation of an ice-ball of the required size, freeze time starts. Freeze time should lie between 5 s and 10 s.
This study is a multicenter study investigating the clinical efficacy of repetitive daylight-PDT with MAL (Methylaminolevulinate) compared to cryosurgery in regard to prophylaxis and treatment of AKs (actinic keratoses) in the face. Patients will be randomly allocated to treatment groups. 5 PDT (photodynamic therapy) treatment sessions (visits 1-5) will be performed within 18 months. In the control group, cryosurgery will be performed at visit 1, and in case of non-cleared or newly occurred AKs at visits 2-5.~In the PDT group the patients will apply a chemical sunscreen (SPF 50+) to the whole face and other light-exposed, unprotected areas of the skin. After at least 15 minutes a lesion preparation of AKs (removal of crusts) will be performed and MAL will be applied in a thin layer to the whole face. Within 30 min after MAL application patients expose themselves to daylight for 2 hours. In the control group, cryosurgery will be performed using liquid nitrogen spray in each AK lesion; this will be done at visit 1 and, if necessary, also at visits 2-5. At visits 2-6, the efficacy of the treatment will be evaluated by the observer by documenting all existing and newly appearing AKs in the face.