UPDATE 2-Doctors debate Vytorin cancer risk at heart meeting

(Adds further panelist, analyst comment)

By Ransdell Pierson and Bill Berkrot

NEW ORLEANS, Nov 12 (Reuters) - Researchers attempted on Wednesday to calm concerns about the potential cancer risks of cholesterol fighters Vytorin and Zetia, while others urged caution in prescribing the drugs until larger trials assess their safety and effectiveness.

Hundreds of cardiologists attended the panel discussion at the annual meeting here of the American Heart Association to glean more insights about the advisability of using the drugs sold by Schering-Plough Corp (SGP.N) and Merck & Co (MRK.N).

"There is no news here other than undue alarm being raised by some about treatments that may well produce further benefits in terms of reducing the risks of heart attacks and strokes," said Rory Collins, an Oxford University researcher who is helping lead a large ongoing Vytorin study called Improve-It.

Oxford colleague Colin Baigent, who is conducting a separate large Vytorin study called Sharp, said cancer data in the two ongoing trials was "reassuring. They have shown us at this point no credible evidence of a cancer risk."

Concerns about a possible cancer link arose in July at a medical meeting in London, when data from a smaller 1,873 patient study called Seas showed substantially more cancer cases among patients taking Vytorin -- which pairs a new type of cholesterol fighter Zetia with Merck's older statin drug Zocor -- than those taking a placebo.

A prominent epidemiologist at the London meeting said cancer risk was unlikely because there was a variety of tumor types rather than a more worrisome cluster of a specific cancer. Moreover, he said patients had taken Vytorin a relatively brief time, while it typically takes many years for cancer to develop.

The panel discussion here on Wednesday brought the Vytorin cancer debate to a major U.S. medical forum.

"We believe the outcome of this morning's Seas debate was unquestionably benign relative to expectations, reinforcing our view that the perceived risk of cancer with Zetia is spurious and that the drug ultimately will be exonerated of this concern," said Leerink Swann analyst Seamus Fernandez.

Still, the Zetia cancer discussion at the heart meeting stood in stark contrast with data presented three days earlier that demonstrated AstraZeneca Plc (AZN.L) cholesterol fighter Crestor dramatically cut the risk of death, heart attack and stroke in a clinical trial, without serious safety issues.

"I think it is impossible to be completely certain, based upon what we currently know, that there isn't a cancer signal" with Vytorin and Zetia, said Allen Taylor, a cardiologist with Washington Hospital Center in Washington, D.C., who joined Collins in the panel discussion.

Taylor said until ongoing large trials definitely prove the safety and effectiveness of the Zetia component of Vytorin, doctors should avoid prescribing the drugs, except for patients who cannot tolerate other treatments.

"That's not many of your patients, but it may be some," Taylor added.

Collins took exception with Taylor's conclusion.

"The suggestion from (Taylor) that this (cancer risk) may be real is undue alarm because there is no support for the hypothesis generated by the Seas trial," Collins said.