ABSTRACT
The nature of retinoid inhibition of growth of malignant cutaneous cells has been studied in detail in murine melanoma Cloudman S91 cells, which were among the first cell lines found to be growth-inhibited by retinyl acetate and retinoic acid. Retinoid induction of differentiation and growth regulation in epidermal cells, as well as the accumulation of selected retinoids in the skin has led to clinical tests for the prevention and therapy of cutaneous cancers. Actinic keratoses are epidermal lesions that have a 3 to 5% probability for converting to nonmelanomatous skin cancer. They occur in Caucasians exposed to high levels of ultraviolet radiation. Keratoacanthomas are hyperkeratotic lesions that resemble cutaneous squamous cell carcinoma. Therapy of basal cell carcinomas has been reported with topical retinoic acid, oral 13-cis-retinoic acid and oral etretinate. Patients with Epidermodysplasia verruciformis develop multiple squamous cell carcinomas and multiple flat, wart-like lesions during childhood.
