(Reuters) - U.S. Food and Drug Administration reviewers said Merck's cholesterol-lowering drug Vytorin was effective in reducing the rate of heart attacks or other cardiovascular problems in patients with kidney disease.

The FDA reviewers also said Merck's blockbuster drug, which pairs a new type of cholesterol fighter Zetia with Merck's older statin drug Zocor, is unlikely to cause or promote cancer.

"Risk of cancer did not increase consistently over time with longer use of ezetimibe/simvastatin, as would be expected if a drug caused cancer or promoted the growth of pre-existing cancers," FDA researchers wrote in documents ahead of an advisory panel that will look at Zetia and Vytorin on November 2.

The FDA review could help allay fears about the popular drug after a 2008 clinical trial showed substantially more cancer cases among patients taking Vytorin than those taking a placebo.

"In our opinion, FDA's review of SHARP strongly supports Zetia's safety," Leerink Swann analyst Seamus Fernandez wrote in a note.

"Most importantly, the FDA reviewer comments and safety review suggest no new safety concerns and that Vytorin/Zetia is not associated with risk of either incident cancer or cancer deaths. We believe these data should help lay to rest investor concerns about Vytorin/Zetia's safety."

Both Vytorin and Zetia, or ezetimibe, are already approved for lowering cholesterol levels. Merck is now hoping to expand the indications to include treating heart problems in patients with chronic kidney disease, which would make it the first treatment with that specific indication.

Chronic kidney disease, which affects about 14 percent of the U.S. population, raises the risk of developing heart disease or having a stroke.

Patents on both Vytorin and Zetia expire in 2017, meaning Merck has only a few years to get more profit from any combination therapy.

Dogged by safety and effectiveness concerns, Vytorin and Zetia have taken hits to their sales. Nonetheless, in 2010 Vytorin posted sales of $2 billion and Zetia of $2.3 billion.

(Reporting by Anna Yukhananov and Alina Selyukh in Washington; editing by Dave Zimmerman and Maureen Bavdek)