BACKGROUND: Non-melanoma skin cancers (NMSC) consists of  basal-cell carcinomas (BCC) and squamous-cell carcinomas (SCC).Certain populations are predisposed to develop  NMSC,  including  patients  with  previous  history  of  NMSC.Systemic  retinoids  have  shown  promising  results  in chemoprevention of recurrence of NMSC in other high-risk populations (xeroderma pigmentosum and renal-transplant patients).We  assessed  the  efficacy  and  safety  of  low-dose  systemic  retinoids  compared  with  placebo,  as  a  chemopreventive agent for NMSC in patients with previous NMSC.
METHODOLOGY: Electronic  databases  were  systematically searched for this study. Participants in the studies selected must have had a biopsy-proven NMSC, over 18 years of age, with  no  exclusion  of  other  demographic  characteristics. All  types  of  systemic  retinoids  were  included  with  no restriction on dosage. Two authors independently performed standardized  eligibility  assessment  and  data-extraction.Differences in opinion were resolved by consensus with the third author. Statistical analysis was done using the Review Manager 5 software.
RESULTS: Eleven full-text studies were assessed for eligibility out of 178 studies found. Five studies were excluded because of the different population, while the two articles used topical retinoids. Four articles were included. The interventions were 10.0 mg isotretinoin, 25,000IU retinol and 25.0 mg acitretin,compared with placebo. Meta-analysis produced RR of 0.94 (95% CI, 0.89-1.00), with moderate heterogeneity (34%) due to the difference in interventions used. There are significantly more  adverse  events  in  the  retinoids  group,  especially  in the  incidence  of  mucocutaneous  adverse  events,  and deranged lipid profile and liver enzymes.
CONCLUSION: There is insufficient evidence to support the use of low-dose systemic retinoids as chemoprevention for patients with previous NMSC. Furthermore, adverse events may limit their use. Topical preparations with less side-effects may be investigated.