Nicotinamide lowers skin cancer risk, strongest after first diagnosis

A widely available over the counter form of vitamin B3, nicotinamide, was associated with a modest overall reduction in new nonmelanoma skin cancers and a large decrease in repeat cancers when started early, according to a retrospective study of more than 33,000 U.S. veterans published in JAMA Dermatology. Researchers found that patients prescribed 500 milligrams twice daily for at least 30 days had about a 14 to 16 percent lower risk of developing a new skin cancer than matched controls, with the greatest benefit seen when supplementation began after a first skin cancer diagnosis.

The study analyzed electronic health records from 33,822 veterans and matched 12,287 nicotinamide users to 21,479 similar patients who did not take the supplement. Across the full cohort nicotinamide use was associated with roughly a 14 percent lower risk of new, procedurally treated keratinocyte carcinomas. The protective effect was stronger against cutaneous squamous cell carcinoma, with an overall reduction of about 20 to 22 percent. Most strikingly, patients who initiated nicotinamide after their first skin cancer experienced a roughly 54 to 56 percent lower risk of a subsequent cancer.