Retinoid chemoprevention of cancers has given mixed results. In the skin, oral retinoids block non-melanoma skin cancers in patients with rare skin cancer-prone syndromes but the results with sporadic skin cancers has been much less sanguine. Since skin is so accessible to topical agents, there remains the hope that high local concentrations attained with topical retinoids may be more effective. So et al. report dramatic inhibition of skin cancer formation by the RAR/ ligand tazarotene in Ptch+/- mice in which basal cell carcinoma production is induced by either ultraviolet or ionizing radiation. These results contrast with the past-reported minimal efficacy of topical all-trans retinoic acid prevention of murine squamous cell photocarcinogenesis. Since topical tazarotene already is approved by the FDA for adolescent acne and senior citizen wrinkles, its assessment as a basal cell carcinoma chemopreventive agent in humans should be forth-coming expeditiously. For details, see the article by So et al. on page 4385 of this issue.

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