This story oversells the results of a case-control study about NSAIDs and cancer. HealthDay’s coverage scored slightly better on our criteria. It is important to convey the limitations of observational data when writing stories about studies with case control or cohort designs.
The story pushes the narrative that anti-inflammatory painkillers, like aspirin and NSAIDs, have an “anticancer benefit.” Here’s what we would have liked to have seen more emphasis on:
Many people are at risk of skin cancer due to genetic factors and a history of unprotected sun exposure. This story might lead some of those people to conclude that a daily aspirin or ibuprofen can help them reduce that risk. In light of the limitations discussed above, however, that would be an unsupported and potentially dangerous conclusion to draw.
Sun exposure is a known modifiable risk factor for skin cancer. This study was unable to account for UV exposure history as it was based on registry data. People who take more NSAIDS may stay out of the sun less, or wear more sunscreen for various reasons. It is impossible to talk about causation from observational data, and this particular study lacks detail on other key risks for skin cancer.
The cost of aspirin and other NSAIDs is not in question.
Although absolute risks generally cannot be estimated from case-control studies such as this one, we think the story could have done a better job putting these statistics into context. For example, the story notes that researchers found a 17% lower risk of basal cell carcinomas (“the most common form of skin cancer in the U.S..”) in those taking long-term, high dose NSAIDs, but doesn’t mention that this cancer almost never spreads beyond the skin. Squamous cell carcinoma is also a slow-growing type of cancer that is usually treated before it can cause complications. Meanwhile, melanoma — a very dangerous type of cancer — is thankfully quite rare, and so the modest 13% relative reduction reported in this study is likely to represent a very small number of cancer cases when put in absolute terms. In the grand scheme of things, the reductions seen were small and many of the cancers possibly prevented would not be clinically important.
The story mentions that aspirin and NSAIDs can cause bleeding and are associated with adverse cardiovascular effects. However, maybe these important caveats should have come sooner than paragraph eight of a nine-paragraph story. Moreover, the story could have provided some sense as to how frequently these adverse events occur and if they are common enough to counterbalance the apparent decrease in cancer associated with these drugs.
The story calls the study “a trial” and suggests that there is a cause-and-effect relationship between NSAIDs and skin cancer reduction — e.g. ” An aspirin a day could keep skin cancer away,” and aspirin use “led to a 46% lower risk of melanoma,..” In fact, this was a case-control study (a type of observational study), a design that is quite susceptible to bias and that can’t support the conclusions that this story draws about NSAIDs preventing cancer. The most we can say is that this research shows an association that needs to be tested in more rigorous studies.
To its credit, the story does note that there were gaps in the information available to the researchers, which may have skewed the comparisons. But this nod to limitations is too little to counteract the story’s overall tilt in favor of benefits.
The story states that basal cell carcinoma (BCC) is “the most common form of skin cancer in the U.S.” While the statement is true, BCC is also the slowest-growing and least dangerous form of skin cancer. Nonetheless, we’ll give the story the benefit of the doubt on this criterion.
No independent sources were quoted. An independent voice could have helped address some of the unanswered questions.
There were no direct references to alternative methods for preventing skin cancer — like using sunscreen, avoiding midday sun, etc. Even an additional line could have satisfied this criterion.
The availability of NSAIDs is not in question.
The story nods to previous research suggesting cancer prevention benefits from NSAIDs.
The story acknowledges lifting a quote from this press release, but there’s no evidence that the story used any other content from the release. We can’t be sure about this one, so we’ll rate it not applicable.
The following is a guest post by Carl Elliott MD, PhD, a professor in the Center for Bioethics at the...
Important news leading into a holiday weekend. Stephen Colbert was back this week with another segment of “Cheating Death” on...
On a BMJ blog, Dr. Margaret McCartney writes about her irritation after seeing ads on the side of buses in...
We will not display your name or e-mail address on the site, nor will we share youre-mail address with any third parties.
For site updates and news from Gary, find us on Twitter:
HealthNewsReview: @HealthNewsRevu
Gary Schwitzer: @garyschwitzer
Copyright © 2013 Health News Review
We Welcome Comments
But please note: We will delete comments that include personal attacks, unfounded allegations, unverified facts, product pitches, profanity or any from anyone who doesn't list what appears to be an actual email address. We will also end any thread of repetitive comments. We don't give medical advice so we won't respond to questions asking for it. Please see more on our comments policy.