Low-dose retinoids in the prevention of cutaneous squamous cell carcinomas in organ transplant recipients: a 16-year retrospective study.

Objective: To evaluate the long-term efficacy of systemic retinoids in reducing the incidence of cutaneous squamous cell carcinomas (SCCs) in organ transplant recipients (OTRs), who are at greatly increased risk of SCCs.

Design: A retrospective before-after study of OTRs who had received low-dose systemic retinoids during 1 to 16 years for prevention of SCCs.

Setting: A specialist dermatology clinic for organ transplant recipients at St Bartholomew's and the Royal London Hospital, University of London, London, England.

Patients: Thirty-two OTRs with at least 1 histologically proved SCC.

Interventions: Continuous systemic retinoids at dosages of 0.2 to 0.4 mg/kg per day for a minimum of 12 months.

Main Outcome Measures: The mean difference between the number of SCCs developing annually during retinoid treatment and the number during the 12-month pretreatment interval.

Results: In 28 continuously treated individuals, the mean number of SCCs in the 12-month pretreatment interval was 2.9. The number of SCCs was significantly reduced, with a mean difference of 1.46 in the first year of treatment (P = .006), 2.20 in the second (P<.001), and 2.14 in the third (P = .02). The numbers of SCCs were also reduced in subsequent years, but this effect was no longer significant because of smaller patient numbers. Six patients in whom retinoid treatment was interrupted subsequently had a significant increase in SCCs.

Conclusions: Low-dose systemic retinoids significantly reduce SCC development in OTRs for the first 3 years of treatment, and this effect may be sustained for at least 8 years, with a generally well-tolerated side-effect profile. Studies are now required to further optimize their use as a chemopreventive strategy in high-risk OTRs.