- has used topical or systemic therapies that might interfere with the evaluation of the study medication during the study. Specifically these include the use of: (i) glucocorticoids to more than 5% of the skin (ii) retinoids systemically or topically to more than 5% of the skin during the six months prior to study entry; (iii) alpha-hydroxy acids to more than 5% of the skin during the six months prior to study entry (iv) 5-fluorouracil or imiquimod systemically or topically to the skin above the knees during the six months prior to study entry. (v) treatment with systemic chemotherapy within one year prior to starting study medication.