A recent statement issued by the study investigators noted that these differences "are small and could have occurred as a result of chance."
While other clinical trial data do not indicate an increase in cancer risk, the FDA is alerting doctors and patients now while it awaits further data from the manufacturers, which they should receive in about three months. After that point, the FDA says it'll take an additional six months for a complete evaluation of the data.
Based on all available data on the link between Vytorin and cancer risk, the FDA says patients should not stop taking Vytorin or any other cholesterol drug.
The American Heart Association says the same thing, recommending that patients taking prescribed cholesterol-lowering drugs should not stop taking them without talking with their doctor. Patients who stop taking prescribed cholesterol medications increase their risk of having a heart attack or other cardiovascular event.
Vytorin is jointly marketed by Merck and Schering-Plough. Schering-Plough tells WebMD it is cooperating with the FDA.
"We believe that the findings in SEAS on cancer are likely to be an anomaly," Schering-Plough's Mary-Fran Faraji tells WebMD. "We don't believe, in light of all the data, that there's an association [of cancer] with Vytorin."
A recent study reviewing cancer risk from Zocor and other cholesterol-lowering statin drugs found no link between statin use and cancer, contradicting its own preliminary findings that did suggest such a link.
"When you put all of the information together, there is no evidence that statins increase the risk of cancer," researcher Richard Karas, MD, says in a news release in response to those study findings.
In addition, interim data from two ongoing trials of Vytorin show no increased risk of cancer in patients receiving the drug. The first of these trials (the SHARP study) won't be finished until 2010; the second (the IMPROVE-IT study) will end in 2012.
In a separate development, the U.S. House Energy and Commerce Committee is investigating the SEAS study and today asked Merck and Schering-Plough for details.
Faraji says both companies are cooperating with that investigation.
Earlier this year, Vytorin suffered another setback when a clinical trial showed that Vytorin did not reduce artery-clogging plaque better than Zocor alone.
WebMD's Miranda Hitti contributed to this report.