Is Vytorin Cancer Risk Real?

Aug. 22, 2008 - Is there really any reason to suspect a link between the cholesterol-lowering drug Vytorin and cancer?

Some experts don't think so. Other experts do. Congressional and FDA investigations are under way.

What's going on? This WebMD FAQ provides a guide to the ongoing story.

What is Vytorin?

Vytorin is a combination of two cholesterol-lowering drugs, the statin drug Zocor (from Merck) and Zetia (from Merck and Schering-Plough). Like other statins, Zocor blocks an enzyme needed for cholesterol production. Zetia works differently: It prevents the gut from absorbing cholesterol.

Does Vytorin work better than a statin drug taken alone?

That's what ongoing clinical trials are trying to find out. Controversy surrounds the first of these trials -- it was finished in 2006, but results came out only this year.

Those results suggested that while Vytorin cuts cholesterol, it does not reduce heart disease any more than a statin alone.

Recently, researchers reported results from a study of Vytorin vs. Zocor alone in patients with narrowing of a major heart valve: the SEAS study, sponsored by Merck.

This report, too, is controversial. Instead of reporting the findings at a major medical meeting, the investigators held a press conference. And instead of publishing the results in a peer-reviewed medical journal, the investigators issued a press release.

The results were not impressive. They suggest that Vytorin did not reduce heart "events" better than placebo, although it did cut cholesterol and also reduced clot-related strokes by 22%.

Does Vytorin cause or promote cancer?

There is no proof that Vytorin causes or promotes cancer.

But in the 2,000-patient SEAS study, patients taking Vytorin died of cancer twice as often as did patients taking an inactive placebo.

The numbers aren't big -- 39 cancer deaths in the Vytorin group (4.1% of patients) vs. 23 cancer deaths in the placebo group (2.5% of patients). But they seem scary. So study leader Terje R. Pedersen, MD, of Ulleval University Hospital in Oslo, Norway, asked for help.

He and his colleagues turned to Richard Peto, FRCP, professor of medical statistics and epidemiology at Oxford University in England. Peto was leading the SHARP study, one of two large ongoing trials of Vytorin (which, like the other trial, IMPROVE-IT, is sponsored by Merck and Schering-Plough).

Peto, a world-renowned expert in cancer epidemiology, took an unusual step. He got permission to take a look at the unblinded data from the two ongoing studies.

The result: Among the 20,000 patients in the two ongoing trials, there were 97 cancer deaths among patients taking Vytorin and 72 cancer deaths among control patients taking Zocor. However, there were about the same number of cancers in each group: 313 cancers in the Vytorin group and 326 cancers in the control group.