Skin cancer chemoprevention with systemic retinoids: an adjunct in the management of selected high-risk patients.

Systemic retinoids (isotretinoin, etretinate, and acitretin) have been shown to be effective chemotherapeutic agents in studies of patients with xeroderma pigmentosum, the nevoid basal cell carcinoma syndrome, and recipients of organ or bone marrow transplantation. In addition, patients who do not have these disorders but who are actively developing large numbers of new skin cancers may also benefit from this approach. All patients developing large numbers of skin cancers need rigorous UV protection and frequent dermatologic examinations. Although isotretinoin and acitretin share overlapping toxicities, there are differences that may affect drug choice. Because low doses may be effective, there are advantages to beginning treatment at a low dose, and subsequently, increasing dose if necessary, based on patient response. Laboratory monitoring including pregnancy testing should be performed before and during treatment. Long-term toxicity, primarily involving the skeletal system, can be monitored with imaging studies.