Beneficial effect of low-dose systemic retinoid in combination with topical tretinoin for the treatment and prophylaxis of premalignant and malignant skin lesions in renal transplant recipients.

Renal transplant recipients experience a greatly increased frequency of neoplastic skin lesions, including aggressive squamous cell carcinomas. Recent reports suggest that high doses of systemic retinoids may exert a chemotherapeutic and chemoprophylactic effect. Similarly, topical retinoid, especially tretinoin, has also been shown to be anti-tumoragenic in various settings. Because of the serious toxicity of high-dose systemic retinoid, a protocol was developed that combined topical tretinoin with low-dose etretinate (10 mg daily) for the treatment of frequently occurring dysplastic skin lesions in renal transplant recipients. Seven patients elected to receive combined tretinoin and etretinate therapy, and 4 were treated with tretinoin alone. Clinical evaluations were performed monthly. By 3 months of therapy, 9 of 11 patients exhibited at least a 25% decrease in the number of neoplastic growths. After 6 months, 6 of 8 evaluable patients, including 2 of 3 individuals receiving tretinoin alone, exhibited at least a 50% decrease. Three of 4 patients on the combined regimen and 2 of 3 receiving tretinoin alone for at least 9 months, exhibited a significant decrease in the rate of development of new squamous cell cancers. At the start of treatment, epidermal specimens were almost completely devoid of Langerhans cells (CD1+ cells). Their density increased greatly and in proportion to the duration of therapy. Long term topical tretinoin with or without low-dose oral etretinate seems to be an effective regimen to suppress the development of new tumors and to reduce the numbers of existing lesions in renal transplant recipients.