Background: Some groups of people have a greater risk of developing common non-melanoma skin cancers (NMSC).
Objectives: To evaluate interventions for preventing NMSC in people at high risk of developing NMSC.
Search strategy: We searched the Cochrane Skin Group Specialised Register (March 2007), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2007, MEDLINE (from 2003 to March 2007), EMBASE (from 2005 to March 2007), the metaRegister of Controlled Trials (February 2007). References from trials and reviews were also searched. Pharmaceutical companies were contacted for unpublished trials.
Selection criteria: Randomised controlled trials of adults and children at high risk of developing NMSC.
Data collection and analysis: Two review authors independently selected studies and assessed their methodological quality.
Main results: We identified 10 trials (7,229 participants) that assessed a variety of interventions. One trial found T4N5 liposome lotion significantly reduced the rate of appearance of new BCCs in people with xeroderma pigmentosum. One of three trials of renal transplant recipients showed a significantly reduced risk of new NMSCs when acitretin was compared to placebo (relative risk (RR) 0.22 95% confidence interval (CI) 0.06 to 0.90) and no significant difference in risk of adverse events in two trials (RR 1.80, 95% CI 0.70 to 4.61). In three trials conducted in people with a history of NMSC, the evidence was inconclusive for the development of BCCs for retinol or isoretinoin. However the risk of a new SCC in one trial (HR 1.79, 95% CI 1.16 to 2.76) and adverse events in another trial (RR 1.76 95% CI 1.57 to 1.97) were significantly increased in the isotretinoin group compared with placebo. In one trial selenium showed a reduced risk of other types of cancer compared with placebo (RR 0.65, 95% CI 0.50 to 0.85) but also a significantly elevated risk of a new NMSC (HR 1.17 95% CI 1.02 to 1.34). The evidence for one trial of beta-carotene was inconclusive; and there was a trend towards fewer new NMSC in a trial of a reduced fat diet (RR 0.16, 95% CI 0.02 to 1.31), p=0.09.
Authors' conclusions: Some preventative treatments may benefit people at high risk of developing NMSC, but the ability to draw firm conclusions is limited by small numbers of trials, often with one trial per intervention or with inconsistent results between studies.