Chemoprevention of basal cell carcinoma with isotretinoin.

Three patients with multiple basal cell carcinomas, due either to excessive sunlight exposure, the nevoid basal cell carcinoma syndrome, or arsenical insecticide exposure, were treated with oral isotretinoin for 2 1/2 to 4 years. Although higher doses were used initially, approximately 1.5 mg/kg/day was used for long-term therapy in all three patients. Therapeutic effects on existing tumors varied between each patient, and only nine of sixty-five lesions underwent complete clinical regression. No tumors enlarged in two patients; a few tumors enlarged slightly in the third patient, particularly during the later courses of therapy when isotretinoin was given at lower dosage. No new lesions have been observed in any of these three patients. With these encouraging preliminary data, it now may be appropriate to perform larger trials for longer periods of time to determine the usefulness of isotretinoin in the chemoprevention of basal cell carcinoma in patients with multiple tumors.