A trial comparing Metvix® photodynamic therapy followed by Mohs micrographic surgery against Mohs micrographic surgery alone for the treatment of basal cell carcinoma

INTERVENTION: To assess whether the combination of PDT followed by Mohs micrographic surgery is superior to Mohs micrographic surgery alone in treating basal cell carcinoma in terms of reducing the post‐Mohs wound defect and the mean number of stages required to achieve clearance CONDITION: Basal cell carcinoma (BCC) ; Cancer ; Basal cell carcinoma (BCC) PRIMARY OUTCOME: 1. To measure and compare the post‐Mohs wound defect surface area (mm^2) in the two groups; 2. To compare the mean number of stages required to clear the lesion by Mohs' micrographic surgery in the two groups; 3. To compare recurrence rates of BCC at 12 months post‐operatively. The lesion response will be defined as one complete response (complete clearance) or zero incomplete response (incomplete clearance). SECONDARY OUTCOME: 1. To assess whether there is any reduction in size (surface area, mm^2) of the lesion, clinically with PDT prior to Mohs (in the Metvix® PDT group) including assessment of fluorescence between the first and second sessions of PDT; 2. Cosmetic outcome at months 3, 6 and 12 after the Mohs surgery INCLUSION CRITERIA: 1. Male or female subjects older than 18 years 2. The above should have a basal cell carcinoma at least 100 mm^2 in surface area and appropriate for treatment with Mohs micrographic surgery 3. Female subject of non‐childbearing potential 4. Subject must be willing and capable of cooperating with the study protocol 5. Subject has to be able to read the patient information sheet as well as read and sign the informed consent form prior to any procedure