Compounds of the hydroxytolan family kill tumor cells, inhibit tumor growth and development, and are thus useful in method for treating a tumor or cancer in subjects in need thereof. These compounds are also active in preventing or treating a variety of skin diseases and conditions. The most preferred hydroxytolan compounds are 4,4′-dihydroxytolan. (KST-201), 4 hydroxy 4′ trifluoromethyltolan or 4′ hydroxy 4 trifluoromethyltolan (KST-213), 3,4′,5-trihydroxytolan or 3′,4,5′-trihydroxytolan (KST-301) and 3,3′,5,5′-tetrahydroxytolan (KST-401). The compounds and methods of using them alone and in combination with ascorbate and certain cyclic compounds to inhibit the development, growth or metastasis of tumor/cancer or preneoplastic cells, or to prevent or treat skin disorders in a subject are disclosed.
