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Cholesterol and cancer risk

Wednesday 25 July 2007

Lowering cholesterol levels with statins may increase the risk of cancer, reported newspapers including the Daily Mail, the Daily Express and The Times .

However, the Daily Mail also stated that “the risk was so tiny – one extra case per 1,000 people – that it was easily outweighed by the benefits in preventing heart attacks and strokes”.

The Daily Express quoted British heart experts, who advised patients “not to alter their intake of statins as the risk of heart problems from not taking them far outweigh the risk of cancer”.

This was generally a well-conducted study, which suggests that the risk of cancer may be increased in people reaching lower cholesterol levels after statin treatment.

However, the links observed in this study do not mean that statins cause cancer, and further investigation is required into the relationship between low cholesterol levels achieved after statin treatment and cancer.

In this type of study it is difficult to rule out the effect of chance or of other unknown influences on the demonstrated link and the authors acknowledge some limitations of the study.

Where did the story come from?

The research was conducted by Alawi Alsheikh-Ali and colleagues from the Molecular Cardiology Research Institute and Division of Cardiology, Department of Medicine, Tufts-New England Medical Center and Tufts University School of Medicine, Boston, Massachusetts. The research was published in the peer-reviewed Journal of the American College of Cardiology .

What kind of scientific study was this?

The study is a systematic review of randomised controlled trials involving statin treatments. Researchers looked at the data to see if there was a relationship between low-density lipoprotein (LDL) cholesterol lowering and rates of elevated liver enzymes, rhabdomyolysis (a disease that destroys skeletal muscle) and cancer.

What were the results of the study?

Among the several results of this study, the researchers found a link between achieved LDL cholesterol levels and rates of newly diagnosed cancer, with cancer rates per 100,000 person-years increasing as level of LDL cholesterol achieved after treatment decreased.

What interpretations did the researchers draw from these results?

The researchers concluded that a concerning link was observed between low cholesterol levels and cancer, which requires further investigation.They suggest that the risk of cancer may, in part, offset the cardiovascular benefits of achieving low cholesterol levels with statin treatment.

What does the NHS Knowledge Service make of this study?

This study used reliable methods to look for research relating to the relationship between the magnitude of LDL cholesterol lowering and rates of elevated liver enzymes, rhabdomyolysis and cancer.

The study did not investigate the rate of cancer in people treated with statins compared with those not treated or given placebo, focusing on differences in rates of adverse events in people taking statins. There are some limitations in the analysis, which are acknowledged by the authors:

  • The results were calculated from summary data in each trial, rather than detailed analysis of individual patient data, which may yield different results.
  • The analysis used rates of adverse events from controlled and restricted environment of clinical trials. Clinical trials often exclude patients with certain conditions that may increase risk of adverse events and they have close follow-up and awareness of early laboratory or clinical signs of toxicity. The relationship between lipid lowering and adverse events may be different in real-life clinical practice.
  • There may be variation in the way adverse events were reported in each clinical trial, and the protocols for monitoring adverse events. Using standardised criteria for recording adverse events may yield different results.

The link between cancer and lower achieved LDL cholesterol levels observed in this study does not mean that statins cause cancer, and further investigation is required into the relationship between LDL cholesterol levels achieved after treatment and cancer.

Analysis by Bazian
Edited by NHS Website

Links to the science

Alsheikh-Ali AA, Maddukuri PV, Han H, et al.

Effect of the Magnitude of Lipid Lowering on Risk of Elevated Liver Enzymes, Rhabdomyolysis, and Cancer.

J Am Coll Cardiol 2007; 50:409-418.