There’s a study just out which has been doing the rounds and receiving a lot of media attention. The study, published in the New England Journal of Medicine , finds that those taking statins are, generally speaking, less likely to die from cancer compared to individuals not taking statins. Perhaps not surprisingly, some seem keen to claim that statins may not only be the answer to heart disease, but our cancer woes too.
But, not so fast. Because the study in question has yielded what is known as ‘epidemiological’ evidence. This tells us that statin use is associated with a reduced risk of death from cancer, but most certainly does not tell us that statins cut cancer risk.
It is well known that studies of this nature are subject what is sometimes described as the ‘healthy user effect’. Basically, what this means is that healthier, perhaps more health-conscious, individuals are more likely to end up on statins than less healthy, not so health-conscious individuals. Because of this, it’s possible that the apparent benefits of statins with regard to cancer (or anything else) have not to do with the statins themselves, but health characteristics of those more likely to be prescribed and take statins.
Statin use increase the risk of cancer
Basically, epidemiological evidence of this nature is unreliable and can easily cause us to draw conclusions that have no foundation in reality.
As any good researcher will know, much more illuminating are what are known as ‘intervention studies’ in which, usually, roughly equivalent groups of individuals are given statins or placebo. These studies, sometimes also referred to as ‘randomised controlled trials’, reduce the risk of the health user effect coming into play. Also, this sort of study mean we can be quite certain that any effect a drug has on health (good and bad) is actually due to the drug (and not a mere association).
One way to get an overview of the effect of a drug or class of drugs on health is to perform a ‘meta-analysis’: a massing together of similar studies. Meta-analyses of intervention studies are not perfect, but they are much better than (crappy) single epidemiological studies like the one currently doing the rounds.
One meta-analysis published in 2009 found that statin use was not associated with a reduced risk of cancer . There has also, previously, been some concern about the impact statins might have on cancer risk in the elderly. In one study, statin use (compared to placebo) increased the risk of cancer by 25 per cent (statistically significant).
Put in this context, the frothing enthusiasm exhibited by some regarding this latest study seems inappropriate. But its another example of what can happen when faith in statins is strong, and some choose to ignore the best evidence in favour of any inferior science that supports their views.
Here’s to a healthy heart
Dr John Briffa
for The Cholesterol Truth
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1. Nielsen SF, et al. Statin Use and Reduced Cancer-Related Mortality. NEJM published online 8 October 2012
2. Brugts JJ, et al. The benefits of statins in people without established cardiovascular disease but with cardiovascular risk factors: meta-analysis of randomised controlled trials. BMJ 2009;338:b2376.
3. Shepherd J, et al. Pravastatin in elderly individuals at risk of vascular disease (PROSPER): a randomised controlled trial. Lancet 2002;360(9346):1623-30