People who had had at least 2 basal cell or squamous cell skin cancers in the previous 5 years took either nicotinamide tablets (a form of vitamin B3) or dummy tablets twice a day for a year. The nicotinamide group developed almost a quarter fewer new skin cancers and fewer precancerous patches, without more side effects; but the effect disappeared after the tablets were stopped. In another study in organ transplant recipients, the tablets did not help.
Immunocompetent patients with at least 2 non-melanoma skin cancers in the previous 5 years; not effective in organ transplant recipients
| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Nicotinamide | 500 mg | Oral | Twice a day |
Dose as in the ONTRAC trial; this supplement has no FDA label for this use. In ONTRANS (transplant recipients, same dose) it gave no benefit. EADO 2026 lists it alongside sun protection; the 2018 AAD guideline considered the evidence insufficient for a recommendation.
Doses follow the trial protocol, guideline or official drug label (source given in the notes of each regimen). Before prescribing, check blood counts, renal and hepatic function, drug interactions and the patient’s condition, and adjust the dose according to the drug label.
Nicotinamide (vitamin B3) 500 mg orally twice a day for 12 months.
Placebo twice a day for 12 months.
Source of the regimen details: Abstract of the paper (N Engl J Med 2015)
Doses are given for the information of specialists, as in this study’s protocol, and are not a prescription. Every drug must be prescribed by the treating physician for the individual patient.
People who had had at least 2 non-melanoma skin cancers (basal cell or squamous cell carcinoma) in the previous 5 years. Participants were examined by dermatologists every 3 months for 18 months. Registration in the Australian New Zealand Clinical Trials Registry: ACTRN12612000625875.
Primary endpoint: number of new non-melanoma skin cancers (basal cell plus squamous cell carcinomas) during the 12-month intervention period. Secondary endpoints: numbers of new squamous cell carcinomas, basal cell carcinomas and actinic keratoses during the intervention period, number of non-melanoma skin cancers in the 6 months after the intervention, and safety.
During the 12-month intervention period, there were no noteworthy differences between the groups in the number or types of adverse events.
The basis for oral nicotinamide as prevention in high-risk immunocompetent people. The 2026 EADO guideline lists oral nicotinamide and sun protection among the ways of preventing squamous cell carcinoma; by contrast, the 2018 AAD guideline considered the evidence insufficient for a recommendation, and the US National Cancer Institute PDQ summary (2025) considers the evidence inadequate. The ONTRANS trial in organ transplant recipients showed no benefit.
A single trial in one country (Australia) with short follow-up; the effect was lost when the drug was stopped and no lasting benefit was shown. The reductions in basal cell and squamous cell carcinoma alone were not statistically conclusive. The results do not apply to organ transplant recipients (ONTRANS was negative).
This summary was prepared by the editorial team from the published paper; the original paper is the final reference. Read the original abstract on PubMed.
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