Of the three stories we reviewed, this one provided the most numbers to describe the study on the anti-cancer benefits of aspirin, but it ended up presenting a picture of the study that was too boosterish and not not realistic enough about the limitations of the study, the potential harms, and the costs.
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.
In contrast to some of the other stories about this study, this one reported that actul numbers of cancer deaths during the origial trials and over the follow-up period (up to 20 years) used by these researchers. “The study looked at eight trials examining the effects of a daily dose of aspirin on preventing heart attacks involving 25,570 patients, 674 of whom died from cancer.” That was almost enough to give it a satisfactory score in our minds, but then there were all those relative differences to contend with. “They showed a 21% reduction in the number of deaths caused by cancer among those who had taken aspirin, compared with people who had not.” Does this mean that 141 (21% of 674) more people lived than died of cancer? And, if so, what are we to make of all the other relative differences? Then, later in the story, it says “Participants were also followed up after 20 years, by which point 1,634 of the original participants had died as a direct result of cancer.” This is followed by more relative differences described in percentages. Still, there was a stronger attempt made here to quantify the benefits than in the other stories, so we are giving it a satisfactory rating, if only barely. The story flunks a key point here by saying the researchers found a 10 percent reduction in prostate cancer deaths when actually the differences in did not reach statisticaly significance. That error reflects a theme throughout this story of portraying the potential benefits as being more certain than the evidence justifies.
Unlike the NPR Shots story, this one failed to provide a clear number about harms. It says, “Previous research has linked aspirin with reductions in heart attacks and strokes, but doctors have been wary when recommending whether people should take daily doses of aspirin because of the risk of gastric bleeding. Rothwell says, “The size of the effect on cancer I think is such that it does more or less drown out those sorts of risks.””
Right at the top there were problems with how this story evaluated the evidence. “Taking aspirin over a long period of time can substantially cut the risk of dying from a variety of cancers, according to a study showing that the benefit is independent of dose, gender, or smoking.” This gives readers the impression that any dose — either miniscule or massive — can have the same benefit, when what the study showed was that there was no additional benefit to be gained from doses higher than the amount found in low-dose pills commonly used by people concerned about heart disease risk. This also implies that women benefited equally to men, when, as the story later notes, “more research is required, in particular for the effect on breast cancer and other cancers affecting women as well as the effect on patients beyond the 20-year period.” There is no discussion of concerns about taking data collected during heart disease trials and then using the information to draw conclusions about cancer, nor was there an acknowledgement of other methodlogical issues raised by this sort of meta-anlysis. On a more basic level, the story does not distinguish between results that were statistically significant and those that were merely suggestive, but might have been the result of chance variations. The story provided a lot of numbers, as we will discuss in the benefits section, but did not bring a lot of clarity to the subject.
The story does not engage in disease-mongering.
The story quotes two outside experts to good effect. One of them, Dr. Peter Elwood, “an expert on aspirin from Cardiff University who was not involved in the study, says that doctors are often reluctant to recommend aspirin because “the risk of causing a bleed by what the doctor prescribes is going to be uppermost in a doctor’s mind.” A patient might interpret the risk differently, he says.”
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 story makes it clear that aspirin has been widely recommended for cardiovascular benefits.
This story did a good job of putting the study in the context of earlier studies by saying, “A previous study by the same authors showed that low doses of aspirin (75-300 milligrams) reduced the number of cases of colorectal cancer by a quarter and deaths caused by the disease by more than a third. The latest study confirms the earlier results and concludes that similar effects can be shown for other types of cancers.”
This story does not appear to rely on a news release.