Researchers have discovered a reasonably widely used cholesterol drug can cause cancer. Or have they?

A number of (mainly British) newspapers are convinced they have:

Cholesterol lowering drug ‘increases risk of cancer by 50 per cent’ – Daily Telegraph

Cholesterol pill warning: Scientists raise fears of cancer link to statin used by thousands – Daily Mail

Cholesterol drug cancer warning – BBC

You might be surprised to know my colleague Alison’s story on over Nature News entitled ‘Cholesterol-lowering drug given cancer all-clear’ is actually about the same study on the same drug. So are the stories ‘Cancer risk of anti-cholesterol drug Inergy played down’ and ‘Experts Say Vytorin-Cancer Link Due To Chance’.

Confusing the issue further, Forbes throws in another point: “experts on both sides of the argument agree on one thing: They don’t like the way the results were made public”.

What’s going on?

Let’s start by going back to the evidence. This hullabaloo is tied to papers published by top medical journal the NEJM. The key paper looks at cancer deaths in patients from three trials given cholesterol lowering drugs ezetimibe and simvastatin (marketed as a combination drug under the names Vytorin and Inegy, but not as some papers have it Inergy).

Its conclusion: “… the currently available results do not provide credible evidence of any adverse effect on cancer of the addition of ezetimibe to statin therapy”.

However, an editorial from the NEJM says: “Ezetimibe interferes with the gastrointestinal absorption not only of cholesterol, but also of other molecular entities that could conceivably affect the growth of cancer cells. The fact that the combined data from all three trials showed an increase in cancer mortality with ezetimibe should not be assumed to be a chance finding until further data are in.”

Why can’t medicine ever give us simple, black and white answers?

There is a more troubling aspect of all of this which is largely glossed over in the search for a yes or no answer. As the study authors note:

The publication of these interim cancer results is a sign of an important and growing problem in the conduct of major clinical trials. Previously, established methods for monitoring interim safety and efficacy data in trials have generally worked well to help ensure that patients are appropriately protected and that treatments are reliably evaluated, and interim results have been made public only if clear evidence of benefit or harm emerged before the scheduled end of the study.

Recently, as in the present case, the unusual levels of public discussion of the safety of drugs have led to public disclosure of interim results to reassure patients and their doctors. The need for such premature disclosure of interim findings could be lessened in the future by the initiation of larger, more definitive outcome trials earlier in the life cycle of potentially important new drugs and devices.

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