, in a survey of members of the American College of Mohs Surgeons.
Although nicotinamide, a vitamin B3 derivative, has been shown to reduce keratinocyte carcinoma (KC) in high-risk patients, it is not approved by the Food and Drug Administration for chemoprevention, and no safe upper limit has been established in clinical trials to date, wrote Sheena Desai of Brigham and Women’s Hospital and Harvard Medical School, Boston, and colleagues.
The investigators emailed an anonymous 12-question survey to 1,500 members of the American College of Mohs Surgeons. Of the 170 who responded, 10 were excluded for discordant responses, leaving 160 participants whose replies were included in a multiple logistic regression analysis. The respondents were mainly U.S. board-certified dermatologists and Mohs surgeons (99.4% for both); 86.9% were in clinical practice, including 78.8% in private practice, according to the report of the results, published in Dermatologic Surgery.
Overall, 76.9% of the respondents said they recommended nicotinamide for preventing KC, and 20% said they had recommended nicotinamide to more than 100 patients in the past year. In addition, 45% of respondents reported patients who had been taking nicotinamide for 2 years or more. Overall, 63.8% of the respondents expressed no concerns about long-term safety of nicotinamide, compared with 28.1% who said they were uncertain about long-term safety. Those who expressed concern or uncertainty about long-term safety were significantly less likely to recommend nicotinamide for KC prevention in the past year (odds ratio, 0.30; 95% confidence interval [CI] 0.13-0.71). Clinicians with more than 10 years in practice were significantly less likely to recommend nicotinamide for chemoprevention (OR, 0.20; 95% CI 0.05-0.82).
The study findings were limited by several factors, including the low number of responses and the potential lack of generalizability to clinicians other than Mohs surgeons, the researchers noted. “Additional studies on nicotinamide safety and use patterns, including cost-effectiveness analyses, are needed given the widespread use identified in this study,” they concluded.
Limited safety data highlight research gaps
The study is particularly important at this time because nicotinamide has been increasingly used for KC chemoprevention since a randomized, controlled trial published in 2015 in the New England Journal of Medicine showed benefits, corresponding author Rebecca I. Hartman, MD, of the department of dermatology, Brigham and Women’s Hospital and Harvard University, Boston, said in an interview. That study of high-risk patients found that nicotinamide, 500 mg twice a day, was safe and effective in lowering the rates of new nonmelanoma skin cancers and AKs after 12 months .
Dr. Rebecca Hartman
“However, because this is not a prescription medication, but rather an OTC vitamin supplement, data on its use are not available,” she said.
Dr. Hartman said she was not surprised that nicotinamide is being used frequently by a majority of the survey respondents. “Most are using this if someone has two KCs over 2 years, which is a quite common occurrence,” she noted. However, “I was a bit surprised that nearly two-thirds had no safety concerns with long-term use, even though this has not been well-studied,” she added.
“Like anything we recommend, we must consider the risks and benefits,” Dr. Hartman said of nicotinamide. “Unfortunately, we don’t know the risks well, since this hasn’t been well-characterized with regular long-term use in these doses,” and more research is needed, she said. “The risks are likely low, as this is a vitamin that has been used for years in various OTC supplements,” she added. “However, there are some data showing slightly increased all-cause mortality with similar doses of a related medicine, niacin, in cardiovascular patients. For this reason, I recommend the medication when a patient’s KCs are really becoming burdensome – several KCs in a year or two – or when they are high-risk due to immunosuppression,” she explained.
“We also must consider the individual patient. For a healthy younger patient who has a public-facing job and as a result is very averse to developing any KCs on his or her face and very motivated to try prevention, it may make sense to try nicotinamide,” Dr. Hartman said. But for an older patient with cardiovascular comorbidities who is not bothered by a KC on his or her back or extremities, “this medication may not have a favorable risk-benefit profile.”
To address safety concerns, “researchers need to examine whether there are any harms in long-term regular nicotinamide use for KC prevention,” Dr. Hartman said. “This is something we hope to do in our patients; however, it is challenging to study in a retrospective way since the harm is likely small and there are so many other features that influence mortality as an outcome,” she noted.
The study received no outside funding. The researchers had no financial conflicts to disclose.