Nicotinamide, an inexpensive, over-the-counter form of vitamin B3, is safe and efficacious for the chemoprevention of nonmelanoma skin cancer in patients at high risk, according to data from the Australian Oral Nicotinamide to Reduce Actinic Cancer (ONTRAC) Study.

Results reported in a press briefing held before the annual meeting of the American Society of Clinical Oncology showed that patients taking nicotinamide were about one-fourth less likely than peers taking a placebo to develop new basal cell and squamous cell skin cancers. They also had a smaller reduction in new actinic keratoses.

“Nicotinamide, vitamin B3, significantly reduced nonmelanoma skin cancers and keratoses in just 12 months in a group of pretty high-risk patients. It’s safe, it’s almost obscenely inexpensive, and it’s already widely commercially available, so this one’s ready to go straight into the clinic,” commented senior investigator Dr. Diona Damian, professor of dermatology at the University of Sydney.

She cautioned that the results apply only to the population studied: adults who had experienced two or more nonmelanoma skin cancers in the past 5 years.

“These are the people we’d be recommending it for – people who have already got a skin cancer track record. It’s not something that we’d recommend at this stage for the general population,” she said. Likewise, the findings do not speak to patients at the other end of the spectrum who are in treatment for advanced or metastatic skin cancer, as they also were excluded.

That said, the researchers are planning additional studies in other populations, such patients who are at high risk because they have immunosuppression, according to Dr. Damian.

“We still need the overall skin cancer prevention strategies of sun-safe behavior, sunscreen, and regular skin surveillance,” she stressed, “but we now have an additional exciting opportunity for affordable skin cancer chemoprevention which we can instantly translate into clinical practice.”

Dr. Peter Paul Yu, ASCO President and a medical oncologist and hematologist who is director of cancer research at the Palo Alto Medical Foundation, Sunnyvale, Calif., commented, “This is a very exciting prevention trial. We all know that we clamor for preventing rather than treating diseases, and this is a major advance for us.”

Exposure to ultraviolet light packs a one-two punch to the skin, both damaging cellular DNA and suppressing the skin’s immune response, according to Dr. Damian. The investigators opted to test nicotinamide as it counters both of these events.

The 386 patients in ONTRAC had heavily sun damaged skin, with a mean of 8 nonmelanoma skin cancers in the past 5 years and 50 keratoses at baseline. They were randomized evenly to receive nicotinamide (500 mg twice daily) or placebo for 12 months.

Results showed that the average number of new nonmelanoma skin cancers per patient during the treatment period was 1.77 in the nicotinamide group and 2.42 in the placebo group. The difference translated to a 23% lower rate of new cancers with the vitamin.

“There were comparable reductions seen for both basal and squamous cell carcinomas,” Dr. Damian noted. “Interestingly, this reduction in skin cancers seemed to start as early as the first 3-month visit. And then when people stopped taking their tablets after 12 months, the benefit was no longer seen. In other words, you need to continue taking the tablets in order for them to be effective.”

The nicotinamide group also had a roughly 15% lower rate of new actinic keratoses, compared with the placebo group.

“Nicotinamide was very well tolerated. There was no difference in adverse events, blood parameters, or blood pressure in the two arms” of the study, reported Dr. Damian. She stressed that it is critically important to distinguish nicotinamide from niacin (nicotinic acid), another form of vitamin B3 that has a host of side effects such as headache and flushing.

“One of the great things about [nicotinamide] is that it really has hardly any drug interactions, which means that elderly patients who may be taking a whole cocktail of medications for their heart disease and their hypertension, and whatever else, the nicotinamide won’t interact with those,” she added.

Some evidence also has shown nonsteroidal anti-inflammatory drugs to reduce the risk of skin cancer. “The advantage of nicotinamide is that it doesn’t have the potential gastrointestinal bleeding or renal side effects of nonsteroidals, so it may be suitable for a group of people who aren’t suitable for taking nonsteroidals,” she said. “In our ONTRAC study, we didn’t find synergy or additional benefit in people who were coincidentally taking nonsteroidals for other indications.”

The trial’s results should be generalizable to similar high-risk patients in less sunny parts of the world, Dr. Damian said. “If their skin has shown that degree of damage to get skin cancer, then we suspect nicotinamide would offer benefits to them as well.”

Dr. Damian disclosed no relevant conflicts of interest. The study was funded by the National Health & Medical Research Council.