The U.S. Food and Drug Administration on Thursday said they were investigating cholesterol lowering drug Vytorin’s link with cancer. One recently concluded trial indicated an increased cancer risk from the drug Vytorin, while two studies that are currently underway have shown no increase in risks.

Vytorin made by a joint venture of Merck & Co. and Schering-Plough Corp is a combination drug made up of the compounds simvastatin and ezetimibe. Designed to reduce levels of LDL and cut the risk of cardiovascular problems, it works by decreasing the production of cholesterol by the liver as well as inhibiting absorption of cholesterol in the intestine.

The FDA said it had received preliminary results from the Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) trial. This was a test to see if lowering cholesterol with the drug Vytorin could reduce the cardiovascular risks in people with narrowing of the body’s largest artery, the aorta. Though the study did not show the cardiovascular risks to reduce they did highlight that many patients treated with the drug Vytorin were diagnosed and died from all types of cancer as compared to those who never received the drug.

The FDA expects to receive a report from Merck/Schering-Plough in about three months and will likely take the agency six months to review the data, but the agency says patients can continue taking the cholesterol lowering drug in the meanwhile. The FDA though has cautioned doctors and health care professionals to monitor any patients on the drug for possible side effects and report them to the agency.

Several Congressional lawmakers issued a demand for data on the trial that showed a link between the drug and cancer after the FDA’s announcement. The House Energy and Commerce Committee Chairman John Dingell and Rep. Bart Stupak, both Democrats from Michigan, said the confusing nature of information released by the companies is troubling.  

The companies, Merck and Schering-Plough have said they would cooperate with the requests though they defended the drug, saying it is effective at reducing cholesterol, the purpose for which it was approved.

Dr. Richard H. Karas, director of preventive cardiology at Tufts Medical Center and leader of a group reporting the finding in the Journal of the American College of Cardiology reported the slight increase in cancer risk among statin users last year. He now said, "The bottom line is that there is no evidence from this work, the largest study published to date, that the cholesterol-lowering ability of statins increases the risk of cancer."

Dr. Daniel Steinberg, professor emeritus of medicine at the University of California, San Diego said that the association between low LDL levels of cholesterol and cancer are not surprising. "The so-called J-shaped curve has been seen repeatedly when cholesterol has been measured," Steinberg said. "In such studies, persons with the lowest LDL cholesterol on entry show the highest death rate from cancer than those with higher LDL levels. This is especially true of cancers involving the blood cell system, but it also occurs with cancer of the kidney and elsewhere," Steinberg said. He further added, "Whatever the mechanism, the main point should be that studies of much larger numbers of people in statin trials find no excess of cancers."

The debate on the cancer data is possibly going to intensify when additional details of the SEAS study are presented at a cardiology conference in Munich on Sept. 2.