This story about the apparent cancer reducing effect of daily low-dose aspirin seen in an analysis of data from a collection of earlier heart disease trials provides a more thorough discussion of the limitations of the latest study and its methods than some of the other stories we reviewed. It also provides more specific information about harms that aspirin can cause and it includes several independent voices that add valuable perspective. As a result, readers will be more likely than those who saw some of the other coverage to understand the call for thoughtful consideration before initiating a daily aspirin regimen in hopes of reaping cancer reduction benefits.
Cancer is the second leading cause of death in the United States behind heart disease, and there are few proven methods for reducing one’s risk of developing the disease. The study discussed in this story provides fairly convincing evidence that a daily low-dose aspirin does indeed prevent some cancers when taken over the course of many years. Because of limitations in the data, however, it is unclear if these benefits will apply to all healthy adults or if they outweigh the risk of side effects, which can include potentially fatal bleeding in the gastrointestinal tract and brain. Individuals need to take these uncertainties into account when deciding whether they want to commit to taking aspirin every day for many years.
The cost of aspirin is not in question. Nevertheless, a broad recommendation to begin taking aspirin daily in middle age would likely be followed by at least hundreds of millions of people, thus the cumulative costs would be large. Also, such widespread use would increase the costs of treating bleeding ulcers and other adverse events caused by aspirin, though hoped-for savings in reduced cancer treatment would be an offestting factor to consider. Still, because the cost of aspirin on an individual basis is low and well-known we won’t insist on this point.
As with some of the competing stories about this study, this report relies too heavily on relative risk figures to describe the potential benefits of aspirin therapy. Quantifying the risk reductions in absolute terms would have provided a more realistic assessment of the advantages. For example, the researchers said that during the course of the original trials there were 674 cancer deaths among more than 25,500 participants, so while it is accurate to say that those taking aspirin had a greater than 20 percent lower risk of cancer death than those taking a placebo, the absolute rate of cancer death was 2.3 percent in the aspirin groups combined vs. 3 percent in the placebo groups combined. The story should have given readers more information about the total numbers of cancer deaths in order to help them put the differences into perspective.
The story provides more information than several of the stories we reviewed about the risks of aspirin therapy. Quoting one of the study researchers, the story notes that about 1 in 1000 patients who take aspirin will experience gastrointestinal bleeding each year, compared 2 to 4 per thousand who will avoid cancer death. While this makes it sound like the benefits of aspirin clearly outweigh the potential harms, the story probably should have cautioned that these data are taken from studies of heart disease. No study has looked specifically at the risks of aspirin when used over the long term to prevent cancer, and it is unclear if different risks might emerge in a population prospectively studied for this purpose. The story also should have mentioned the increased risk of hemorrhagic stroke — which is frequently fatal — associated with aspirin use.
This story is better than some other stories at describing what happened in this study and mentioning potential limitations. It notes that the findings don’t necessarily support new recommendations for everyone to take aspirin, but it goes further than some others in describing why the results might not be broadly applicable. It notes that the study included primarily men, so the data don’t tell us if aspirin can prevent breast cancer, the most common cancer in women, or other common cancers such as ovarian cancer. The story also notes that participants in these studies may have stopped taking aspirin after the initial trial period was over. (Conversely, they may also have started taking aspirin if they were in the placebo control group.) This loss of randomization can make it difficult to assess the true effects of aspirin on deaths occurring many years later. We wish the story had given more attention to an important drawback of the study: the fact that it was not designed and prospectively initiated as a study of cancer outcomes, and did not provide data on harms. However, we think the story provided enough information to give readers a reasonably balanced view of the issue.
The story did not exaggerate the impact of cancer and it accurately described the possible relevance of this study to a large segment of the population.
The story quotes from interviews with the study researchers and 3 independent experts. That’s the most important factor in this case, so we will pass this story on this criterion. However, while the study itself did not receive outside funding, readers should have been told that some of the authors have had consulting relationships with pharmaceutical companies.
Some of the other news stories about this study pointed out that avoiding smoking and obesity are known to reduce cancer risk. This story should also have pointed out these options, which also do not have potential adverse effects.
The availability of aspirin is not in question. Also, the story points out that low-dose aspirin is currently used by some people to reduce their risk of cardiovascular events.
The study discusses the previous research that led to the current study and does not oversell the novelty of the new findings.
This story does not appear to be based on a news release.