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Balanced, complete evaluation of study on vitamin supplements for skin cancer prevention

Study: Vitamin B3 may help prevent certain skin cancers

Our Review Summary

It’s an attractive idea: Take a cheap, harmless, over-the-counter pill twice a day and lower your chance of developing skin cancer. But as this well-balanced Associated Press (AP) news story illustrates, the results of a new study of Australian cancer patients who took nicotinamide — a type of B vitamin — are nowhere near that simple. First, the article explains that the benefit is quite modest in absolute terms and applies only to people who’ve had recurrent basal and squamous skin cancers — not people with more-lethal melanoma skin cancer, nor those without skin cancer who are trying to prevent getting it in the first place. Second, nicotinamide is sometimes confused with niacin, another B vitamin with more side effects. Third, the modest protection tapered off rapidly once study participants stopped taking nicotinamide. The story responsibly indicates that typical preventative methods — limiting exposure, shade, and sunscreen — are tried and true.

Although AP’s coverage is clearly superior to the competing CBS story on the same study, both pieces could have done a better job explaining that the findings — based on a conference abstract that has yet to be presented — haven’t undergone full peer review and should be considered preliminary until they are published in a journal.


Why This Matters

Skin cancer affects about 5 million people in the U.S. each year, making it one of the most common forms of cancer, and rates have been on the rise for the past three decades (probably because people are living longer, getting more sun exposure, and enjoying better detection methods). Most of these cancers are basal and squamous cell cancers, which typically aren’t lethal and affect about 2.2 million Americans every year. But those with either form of cancer have increased risk of being diagnosed with melanoma–a more deadly skin cancer that affects 74,000 and kills about 10,000 Americans annually.Overall, the lifetime risk of getting any skin cancer is 20 percent, and the risk of dying from melanoma is about 2.4 percent–so any potential prevention method, especially a simple one, is bound to receive widespread attention.


Does the story adequately discuss the costs of the intervention?


The story informs us online retailers sell nicotinamide “for prices ranging from a nickel to a dollar a tablet.” That’s pretty cheap, but leaves one to wonder why the price difference per pill can be as drastic as 20-fold.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?


The benefits are clearly laid out in this story: Australians with basal or squamous skin cancer who take a daily nicotinamide supplement see 23 percent less recurrences of those cancers. The benefit is also quantified in absolute terms: “In absolute terms, it meant that vitamin takers developed fewer than two of these cancers on average versus roughly 2.5 cancers for the others.” Participants also saw, after 9 months of taking the daily supplements, a 20 percent reduction in scaly patches of skin that can lead to cancer. Those benefits are also well-caveated with expert quotes, e.g. “At the moment, it’s not something for the general population” and “The benefit wears off fairly quickly” after people stopped taking nicotinamide.

Does the story adequately explain/quantify the harms of the intervention?


The story describes nicotinamide as a benign substance and quotes a study author who said there are “essentially no side effects.” That claim can’t be verified without a look at the actual study data (which hasn’t been published yet), but the piece takes care to lay out some important and related harms, e.g:

  • Confusing nicotinamide with niacin, another B3 vitamin that can have significant side effects (“flushing headaches, blood pressure problems”) or nicotine (“It is not the same as nicotine”)
  • Thinking these benefits apply to people with melanoma (“The study did not involve melanoma”)
  • Assuming this in any way substitutes highly effective skin cancer prevention methods (“‘We must always remember the basics of sun-sensible behaviors’ – avoiding overexposure and using sunscreen – as the best ways for anyone to lower risk, she said.”)
  • Other vitamin treatments are known to do nothing — or even make some cancer cases worse (“Vitamins have long proved elusive for cancer prevention, and some studies have even found certain ones can be harmful).

Does the story seem to grasp the quality of the evidence?


The story properly hemmed in the nature of the results and added expert commentary to boot. For example, the story noted the control group, from which the benefit percentages are derived, and what happened to the study participants after they stopped taking nicotinamide: “Participants were tracked for six months after they stopped taking their pills, and the rate of new skin cancers was similar in both groups.” The story appropriately calls attention to the fact these results haven’t been replicated outside of Australia. E.g.: “Australia has higher rates of skin cancer than the U.S. and other parts of the world, and some doctors may want more evidence beyond this single study before recommending the pills.”

Our main concern is that the story gives no sense of the preliminary nature of these findings, which come from an abstract for a meeting of cancer specialists occurring a few weeks from now. The story notes that the findings were released “in a telephone news briefing” ahead of the meeting, but it doesn’t explain why that’s a reason to view them cautiously. These results haven’t been published in a journal, which means they haven’t undergone full peer review and nobody has had a chance to scrutinize the complete study data.

We’ll call this Satisfactory with suggestions for improvement noted for next time.

Does the story commit disease-mongering?


Nothing about this story inflates the nature of basal or squamous skin cancers. In fact, it’s quick to use an outside expert to say, “They’re rarely lethal but they’re very persistent and they keep coming back.”

Does the story use independent sources and identify conflicts of interest?

Not Satisfactory

The story quotes one Dr. Richard Schilsky, chief medical officer of the American Society of Clinical Oncology, who appears to be an outside expert — but his quotes only address background information regarding skin cancer and nicotinamide, not the study’s results or methodology. We have to assume the writer asked him about the results, and that his responses were unsurprising and/or unquotable. But it would have helped this story to mention his opinion on the work. The story mentions the funding source for the study, and although potential conflicts of interest among the study authors aren’t addressed, a quick search revealed nothing that would have been important to mention.

Does the story compare the new approach with existing alternatives?


Typical treatments are discussed, e.g. surgical removal, radiation, and cryogenic freezing of cancerous tissue. Avoiding sun exposure is appropriately emphasized.

Does the story establish the availability of the treatment/test/product/procedure?


We’re not only told nicotinamide is cheap and available over-the-counter in drug stores, but also that it’s sometimes hard to find and easily confused with niacin.

Does the story establish the true novelty of the approach?


The story addresses novelty in the first sentence: “For the first time, a large study suggests that a vitamin might modestly lower the risk of the most common types of skin cancer in people with a history of these relatively harmless yet troublesome growths.”

The story also contrasts the nicotinamide results generally with other research that has probed the use of vitamins in preventing or treating cancer.

Does the story appear to rely solely or largely on a news release?


We don’t see any evidence of reliance on a news release, and it’s indicated at the end of the story that the results were discussed via a telephone conference.

Total Score: 9 of 10 Satisfactory


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