This story about aspirin’s potential benefits in cancer prevention does a better job than some others we reviewed, yet this story still left a lot of gaps in the picture. The overall tone couched the potential benefits in cautious statements about the potential risks of aspirin and scitific uncertainties that this study leaves unresolved. The story was one of the few to quantify the potential harms involved in taking aspiring daily. It also made good use of outside experts. However, we wish it had provided readers with more of the absolute numbers behind what appear to be stunning relative differences in treatment effects. There were clear examples of the small differences in the absolute number of deaths featured in the study that could have been featured in the coverage here and elsewhere.
Aspirin’s benefits to reduce cardiovascular problems are well established, but there appears to be a growing body of evidence about its strengths in preventing certain cancers, too. If aspirin turns out to be a simple solution to preventing cancer with negligible side effects, it could prove to be a massive boon to health worldwide. With stakes this high, it’s all the more important for reporters to carefully weigh the evidence and explain to readers the science in clear terms with real numbers.
This story does not discuss the cost of daily aspirin intake. Because the cost to individuals is low and well-known, we won’t insist on this point. Nevertheless, were a recommendation made for everyone to begin taking aspirin daily starting at age 45 the national price tag would be substantial. Readers would also benefit from an acknowledgement that such a recommendation would lead to higher spending on treatment of bleeding ulcers and other adverse events that would offset some of the potential cancer-related savings.
This story does not put the relative differences between aspirin and placebo in these studies into the proper perspective. The story says, “For some of these cancers, the reduction in death was remarkable.” What is considered remarkable? “Twenty years after people had started taking aspirin regularly (and kept it up for at least five years), their deaths from esophageal cancer were reduced by 60 percent compared to study subjects who got a placebo.” How many people died from esophageal cancer? We never find out. In fact, we don’t know how many people died period. There is a mangled sentence in the story that indicates that the study captured “cancer deaths for up to 20 years after those studies ended [for]… nearly 13,000 people.” Esophageal cancer is rare compared to other cancers studied, and its low numbers may account for the high relative difference in preventative benefits of aspirin. To make that determination, though, readers would need the absolute differences. The story should have at least mentioned the number of cancer deaths. Telling readers that 674 participants died of cancer out of more than 25,000 included in the original studies would help them understand the actual size of any reduction in risk. The same is true for the claims about risk reduction over a 20 year period, where there were a total of 1634 cancer deaths among 12,659 participants. When readers are told of a “20 percent reduction” they should be told it was 20 percent of the number of actual cancer deaths, not 20 percent of the much, much larger total number of participants.
This is one of the few stories to put a number to the potential harms. “But aspirin carries risks. The biggest is stomach bleeding, although it also raises the risk of brain hemorrhage. Daily aspirin doubles a person’s gastrointestinal bleeding risk to about 2 in every 1,000 people a year. But Rothwell says this bleeding hazard is “drowned out” by the cancer benefit.”
This story performs better than some others in presenting the quality of the evidence. First, it takes a cautious tone from the top. The second sentence says, “A British study offers compelling — though not clinching — evidence that the humble aspirin tablet can prevent death from a variety of cancers, if you take the medicine long enough in middle age. Don’t start popping aspirin every morning to fight tumors without talking to your doctor, though.” Secondly, it provides more details about the study, although we would have liked to have seen more. For example, the story says, “The new study didn’t find any anticancer benefit for aspirin doses above 75 milligrams a day — the British dose for a “baby” aspirin. In the United States, a baby aspirin weighs in at 81 milligrams. However, experts say more information is needed on the optimum dose for cancer prevention.” But then it allows a researcher with an unsubstantiated claim to get in the last word. “There’s a little controversy about whether a baby aspirin dose is enough,” says Harvard’s Chan. “We think that probably a standard adult aspirin dose of 325 milligrams is more likely to be effective.” One important point that is neglected here is the limited data in women in this study.
Also, the story says the study “encompasses eight earlier studies that compared cancer deaths among more than 25,000 people randomly assigned to get aspirin (of different doses) or placebo.” What readers aren’t told is that those earlier trials were looking at heart disease, not cancer. Readers should have been alerted that the data is being analyzed in ways that were not part of the original study designs. There may be gaps or other issues in the original data that raise dome questions about how solid the study results really are. Nevertheless, the overall tone is appropriate to the quality of the evidence.
The story does not engage in disease-mongering.
The story makes pretty good use of outside sources. It points out that “the U.S. Preventive Services Task Force’s currently recommends against taking aspirin to prevent colorectal cancer, the type of cancer for which there is the largest body of scientific work.” At the same time, the statement that the effects on cancer are larger than for heart disease is misleading for middle-aged and older adults who are not at high risk for cancer. Heart disease is 10 times more likely in these populations, so even with a lower relative risk reduction, more heart attcaks are going to be prevented than cancers.
The story would have been better if it had told readers that although this study received no outside funding, some of the authors have had consulting relationships with pharmaceutical companies.
This story does not present alternative ways of reducing cancer risk. Some other news reports specifically noted that avoiding smoking and obesity are both known to reduce cancer risk.
The availability of aspirin is widely known. What is unique here is how common is it to be used as a cancer prevention method. This story, like others, makes clear that it is commonly used for other reasons but not for cancer prevention. “To be sure, the U.S. Preventive Services Task Force’s currently recommends against taking aspirin to prevent colorectal cancer, the type of cancer for which there is the largest body of scientific work. The benefits of daily low-dose aspirin can exceed the risks for many middle-aged and older people when it comes to preventing heart attacks and strokes, the task force says. So for those already taking prophylactic aspirin for this reason, the possible anticancer effects are just icing on the cake.”
The story makes it clear that aspirin has been studied as a potential preventative tool for other cancers but that aspirin is not in wide use for this purpose.
This story does not appear to rely on a news release.
Systematic, Criteria-Driven
The tale of two “negative” studies. Or, how spin is applied to make research findings look more impressive. A must read. https://johnmandrola.substack.com/p/the-tale-of-two-negative-studies
The @nytimes chose to interview one of the editors of the @AnnalsofIM (publisher of this paper) who "gushed with extraordinary glee: It’s huge! There are very few things that reduce your mortality by 30%."
Turns out coffee is not one of those few things despite all that glee. https://twitter.com/garyschwitzer/status/1533202075928215558
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