Nicotinamide is the precursor of nicotinamide adenine dinucleotide (NAD+), an essential cofactor for adenosine triphosphate (ATP) production. It has recently been reported to be effective in reducing the rates of new non-melanoma skin cancers (NMSCs) and actinic keratosis (AKs). We studied the efficacy of oral nicotinamide as treatment for AKs in transplant recipients. We recruited 38 transplant (eight liver and 30 kidney) patients with single or multiple AKs. Nineteen patients were randomly assigned to Group 1 and took nicotinamide 500 mg/daily (cases); the other 19 patients were randomly assigned to Group 2 without nicotinamide (controls). At baseline, AKs were identified, measured, and photographed for follow-up. Five patients underwent an AK biopsy for histopathology. Statistical analyses were performed using the Student t test. At baseline, no statistically significant differences were observed regarding AK size between the two groups. After six months, among the cases, AKs had significantly decreased in size in 18/19 patients (88%). Among these 18 patients, seven patients (42%) had shown complete clinical regression and no patient developed new AKs. Conversely, among the controls, 91% showed an increase in AK size and/or developed new AKs. Seven pre-existing AKs progressed to squamous-cell carcinoma. Nicotinamide appears to be effective in preventing and treating AKs, although the mechanisms are still unclear. Further studies with a larger sample of organ transplant recipients and a longer follow-up period are needed to further support our conclusions.
Keywords: actinic keratosis; nicotinamide; non-melanoma skin cancer; squamous-cell carcinoma; transplant recipients.