Prevention of skin cancer in xeroderma pigmentosum with oral isotretinoin.

To confirm reports that skin cancer can be prevented with retinoid treatment, a three-year controlled prospective study was conducted of oral isotretinoin in five patients with xeroderma pigmentosum who had a history of multiple cutaneous basal cell or squamous cell carcinomas. Patients were treated with isotretinoin, 2 mg/kg per day for two years, and then evaluated for an additional year without using the drug. Before, during, and after treatment, biopsy specimens of all suspicious lesions were examined, and skin cancers were removed surgically. The patients had a total of 121 tumors in the two years before treatment. During two years of treatment with isotretinoin, there were twenty-five tumors, with an average reduction in skin cancers of 63 percent (p = 0.019). After use of the drug was discontinued, the tumor frequency increased a mean of 8.5 times over the frequency during treatment (p = 0.007). Although all patients experienced mucocutaneous toxic effects, and abnormalities in triglyceride levels, results of liver function tests, or skeletal findings occurred in some, high-dosage oral isotretinoin was effective in the chemoprophylaxis of skin cancers in patients with xeroderma pigmentosum.