Nicotinamide and skin cancer chemoprevention: The jury is still out.

Following the publication of the results of a Phase III trial, the administration of oral nicotinamide has been widely advocated as effective in non-melanoma skin cancer chemoprevention in high-risk individuals. However, I performed a Bayesian analysis of the reported findings and show there is insufficient evidence to demonstrate its efficacy, highlighting the significant probability that the positive conclusions drawn will not be reproducible. Given the potential widespread use of oral nicotinamide, future position statements regarding its efficacy are likely to require higher standards of evidence.