Oral Isotretinoin Versus Topical Tretinoin for Actinic Keratosis

Actinic keratosis (AKs) are premalignant disorders that can evolve into skin cancer. To prevent their development, a study is being conducted with oral isotretinoin and topical tretinoin to verify what drug is the most effective and has the best security profile for these patients. Along with these treatments, cryotherapy with liquid nitrogen and sunscreens will be part of the treatment. The study will have the duration of 10 months. In the first four months, the AKs will be counted and treated with cryotherapy (face and arms) and sunscreens FPS 60 will be used. After it, the patients will return (the AKs will be counted), a new session of cryotherapy will be performed and they will be randomized into two groups: one group using oral isotretinoin 10mg/day ( ISO: 30 patients) and the other one using tretinoin 0,05% cream (AR: 30 patients) applied on face and arms. Skin biopsies will be done for all 60 patients at the beginning of the treatment with retinoids (isotretinoin and tretinoin). After six months of treatment with retinoids, the study will be stopped, AKs will be counted again and skin biopsies will be done. Patients in the group ISO (oral isotretinoin) also have to make blood tests at the beginning, two months and after six months of the treatment. Clinical (AK counting), histological (improvement of parts of the skin) and immunohistochemical parameters will be evaluated to see what drug is more effective for prevention of AKs.