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Statins Cleared of Causing Cancer
  By Michael Smith, North American Correspondent, MedPage Today
Published: August 25, 2010
Action Points
* Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
* Explain to patients that if and when this large study is published in a peer reviewed journal it should lay to rest any fears that statins are associated with an increased risk of cancer.
STOCKHOLM -- In what may be the final word on the issue, an international team of researchers report that statins neither cause nor prevent cancer.
The finding comes from a meta-analysis of 25 randomized controlled trials of the lipid-lowering medications, according to Jonathan Emberson, PhD, of the University of Oxford, and colleagues in the international Cholesterol Treatment Trialists' Collaboration.
In those trials, which included more than 166,000 participants, there were no differences between treatment and control arms in terms of the incidence of cancer or the rate of cancer mortality, Emberson said in a telephone interview.
He will report the results next week in a presentation at the annual congress of the European Society of Cardiology here.
"Randomization to statin therapy for at least five years had no effect on the incidence of cancer or of cancer mortality in any group of individuals," Emberson told MedPage Today.
The main goal of the trials was to establish the effect of statins on lipid levels, and especially how changes in lipids affected the risk of major cardiovascular events. But Emberson said the collaborative group planned from the beginning to get data on cancer mortality, based on individual patient-level data from all the studies.
"Because we have individual patient data, we can really look at particular hypotheses and test them," he said -- something that many meta-analyses can't do.
The researchers conducting the trials were asked to track cancer, he said, because of observational studies that had suggested that lower cholesterol was linked to a higher risk of cancer. It now seems likely that those results arose from residual confounding or perhaps reverse causality, since it is known that the early stages of cancer can have the effect of lowering cholesterol, he said.
There have also been observational studies suggesting the opposite effect -- that statins prevent cancer.
The 25 studies included 20 in which a statin was compared to placebo, involving 126,753 participants, and five in which higher and lower doses were compared, involving 39,612 participants. All the trials had at least 1,000 participants and lasted at least five years, Emberson said.
The investigators calculated rate ratios for the effect on cancer incidence and cancer mortality of each 1.0 millimole per liter reduction in low-density lipoprotein cholesterol.
All told, they reported, 9,954 participants developed cancer and 3,498 died from it.
But reducing LDL cholesterol with a statin had no effect on the risk of developing cancer or on the risk of cancer death:
* In the 20 statin versus control trials, cancer incidence in the treatment arms was 3,502 (or 1.4% a year) versus 3,514 cases in the control arms (also 1.4% a year), for a rate ratio of 0.99.
* In those trials, there were 1,289 deaths among those taking statins versus 1,281 in those getting the placebo -- 0.5% a year for both -- leading to a rate ratio of 1.00.
* In the five trials of more versus less statin, cancer incidence was 1,466 versus 1,472 (1.6% a year for both arms) yielding a rate ratio of 1.02, while cancer mortality was 447 deaths versus 481 (0.5% a year for both arms) for a rate ratio of 0.88 and a 95% confidence interval from 0.67 to 1.15.
* There was no evidence of any effect of statin therapy on cancer incidence or mortality at any particular site, with increasing years of treatment, or in any particular subgroup.
The only gap, Emberson said, is that the study only covers five years of treatment and it remains possible that an effect might be seen after longer therapy. But he said that some of the studies now have a decade of data and no evidence of a long-term effect has emerged.
While statins are widely used, there has been "an ongoing background worry" among physicians that they might cause harm, according to Chris Cannon, MD, of Brigham and Women's Hospital in Boston.
That fear has now been laid to rest, he told MedPage Today.
"The key message is that statins are safe and there's no issue of increasing cancer," he said. "And there's also no effect of reducing cancer, at least in a five-year time frame."
The data, he said, meet the "gold standard" of randomized trials and "trump the many observational analyses that have come out on both sides of the equation."
Emberson said he had no financial conflicts.
Cannon reported research funding from Accumetrics, AstraZeneca, Bristol-Myers Squibb/Sanofi Partnership, GlaxoSmithKline, InteKrin, Merck, Novartis, and Takeda, and an advisory and ownership relationship with Automedics Medical Systems.
Primary source: European Society of Cardiology
Source reference:
Emberson J, et al "Safety of statin therapy: meta-analysis of data on cancer from 166,000 participants in 25 randomised trials" ESC 2010; Abstract 5035.
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