Vitamin B3: an ally against skin cancers

Each year, millions of patients undergo excision of basal cell or squamous cell carcinoma, the two most common skin cancers. In the United States, it is estimated that nearly six million people are treated annually for non-melanoma skin cancer, at a cost exceeding US$8.9 billion. In Canada, approximately 80,000 new cases of skin cancer are diagnosed each year, and their incidence is steadily increasing due to the aging population and cumulative UV exposure.While photoprotection and the treatment of actinic keratoses form the backbone of prevention, their effectiveness largely depends on patient adherence, which is often low: Surveys show that less than half of people follow the recommendations for regular sunscreen use. The search for a simple, inexpensive, and well-tolerated oral agent therefore remains a priority in public health and dermatology. In this context of increasing incidence and incomplete prevention, nicotinamide—a form of vitamin B3 already available over-the-counter—is attracting attention as a potential adjunct. Following encouraging signs from smaller-scale trials, an American team has just published the most comprehensive analysis to date on its effectiveness in secondary prevention.The team of dermatologist Kimberly F. Breglio (affiliated with Durham Veterans Affairs Medical Center and the University of Michigan), in collaboration with several American research centres, used data from the Veterans Health Administration. Their study, recently published in JAMA Dermatology, included more than 33,000 veterans who had experienced at least one skin cancer.The objective: to evaluate the effect of nicotinamide, a derivative of nicotinic acid also known as vitamin B3 or PP, on the secondary prevention of carcinomas. "Nicotinamide has shown chemopreventive potential in small trials, but large-scale data were lacking," the authors noted in their introduction.30,000 patients screenedResearchers conducted a retrospective matched cohort study using electronic health records from the Veterans Health Administration between 1999 and 2024. Of the 33,822 patients included, 12,287 had received nicotinamide (500 mg twice daily for at least 30 days), and 21,479 had never taken it. The groups were matched for age, sex, number of previous skin cancers, comorbidities (including chronic lymphocytic leukemia and organ transplantation), and exposure to other preventive therapies (acitretin, phototherapy, fluorouracil).The primary outcome was the time to development of a new basal or squamous cell carcinoma. Survival analyses were stratified according to the number of skin cancers that had already occurred before the introduction of treatment.Compelling resultsThe study highlights an overall 14% reduction in the risk of new skin cancers in patients exposed to nicotinamide (relative risk [RR] 0.86;≈ 95% confidence interval [CI] 0.82–0.89). But the most striking signal appears when the drug is started after the first diagnosis: the risk then drops by 54% (RR 0.46; 95% CI 0.39–0.49).This benefit diminishes with each recurrence and becomes negligible when treatment is prescribed after seven or eight successive cancers. “The timing of treatment initiation was a crucial factor: patients who started nicotinamide early derived the maximum benefit,” the researchers emphasized.By histological type, protection was most pronounced for cutaneous squamous cell carcinomas, with a 22% reduction (RR 0.78; 95% CI 0.75–0.82). No overall decrease was observed for basal cell carcinomas (RR 1.00; 95% CI 0.96–1.05), except when the drug was prescribed for the first or second cancer.In solid organ transplant recipients (3.9% of the cohort), the overall effect was not significant. However, when nicotinamide was initiated after one or two cancers, the risk of squamous cell carcinoma was reduced by 53% (RR 0.47; 95% CI 0.23–0.97).According to the authors, these results confirm the role of nicotinamide as a secondary prevention tool but emphasize the importance of initiating it early. “The use of nicotinamide was associated with a reduction in the risk of skin cancer, with a maximum effect when it was started after the first diagnosis,” they concluded.They also noted that the benefit is visible even after adjusting for other preventive measures such as acitretin or phototherapy, which are often less well tolerated. The protective effect is evident after just 30 days of exposure.Multimodal strategy In an editorial accompanying the article, Dr. Sarah T. Arron emphasizes the clinical significance of these results: “The growing body of literature suggests that we should recommend nicotinamide for secondary prevention to all patients with a history of skin cancer, and that early initiation maximizes its effect.”The dermatologist, affiliated with the Palo Alto Medical Foundation in California, reminds us, however, that vitamin B3 supplementation must be part of a multimodal strategy, combining photoprotection, education and field treatments. “Patients are most receptive when they receive their initial diagnosis or during surgery: These moments provide an ideal window to introduce nicotinamide,” she wrote.Regarding transplant recipients, her editorial emphasizes that the data remains uncertain. Acitretin is better documented, but nicotinamide could be considered as an alternative or complement if prescribed early, Dr. Arron pointed out.While nicotinamide has not yet been included in official guidelines, it is already recommended by many American dermatologists and is included in some sunscreen supplements. The study by Dr. Breglio and her colleagues, due to its unprecedented scope, provides a strong argument in favor of its wider adoption.For Dr. Arron, the challenge now is to integrate this option into clinical practice, not as a panacea, but as an additional component of prevention. As she emphasized, “Nicotinamide is widely available, well-tolerated and inexpensive. Our responsibility is to educate patients on its appropriate use, in addition to other measures.”

Vitamin B3: an ally against skin cancers

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