PDT can be used therapeutically to treat superficial skin cancers (known medically as superficial or nodular basal cell carcinomas or squamous cell carcinoma in situ) and certain precancerous lesions (known medically as actinic keratosis). Metvix PDT is an alternative treatment to cryotherapy, skin cancer creams or surgery, all of which can potentially leave unsightly scars. PDT has no documented history of scarring and provides an excellent cosmetic result especially in cosmetically sensitive areas. Clinical studies have found that most patients who have had previous treatment for actinic keratosis with cryotherapy or skin cancer creams were more satisfied with PDT.