WEDNESDAY, Aug. 20 (HealthDay News) -- Researchers who last year reported a possible link between cholesterol-lowering statin drugs and cancer now say that further analysis has disproved such an association.

Statin medications include such blockbusters as Crestor, Lipitor, Pravachol and Zocor.

"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," said 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.

A little more than a year ago, a report by Karas and his colleagues in the same journal described a slight increase in cancer risk among statin users -- about one extra case per 1,000 people. That finding came from 13 trials that gathered information on side effects reported by people who took the drugs.

The newer report has data from 15 controlled trials involving more than 437,000 person-years of follow-up. The analysis did find a relationship between low levels of LDL cholesterol -- the "bad" kind that clogs arteries and that statins attack -- and a higher incidence of cancer. However, the team concluded that statins, per se, "lack an effect on cancer risk across all levels of on-treatment LDL cholesterol."

An even larger study by Sir Richard Peto, the renowned British epidemiologist, reported at a meeting but not yet published in a medical journal, came to the same conclusion, Karas said.

An association between low levels of LDL cholesterol and cancer is no surprise, said Dr. Daniel Steinberg, professor emeritus of medicine at the University of California, San Diego. He wrote an editorial accompanying the report.

"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."

One possible mechanism is that cancer itself reduces LDL cholesterol levels, he said. "This is especially true of cancers involving the blood cell system, but it also occurs with cancer of the kidney and elsewhere," Steinberg said.

"Whatever the mechanism, the main point should be that studies of much larger numbers of people in statin trials find no excess of cancers," he added.

Karas said he took "several important messages" from the studies. "We need to do a much better job of keeping track of these relationships," he said. "In major trials of statins, some do not even report on the number of cancers. We need a lot more research in this area. In terms of biology, virtually nothing is known."

And the case is not completely closed yet, said Dr. Ori Ben-Yehuda, professor of medicine at UCSD and co-author of a second editorial.

Studies thus far have dealt with people in the mass, comparing average levels of LDL cholesterol with overall cancer risk, Ben-Yehuda noted. "What we need is patient-level data to see whether a pattern emerges of different risks at different LDL levels," he said.

Lingering doubts should not stop people from using statins, especially for those who clearly are at risk of heart disease, Ben-Yehuda said. "But when we give medications to millions, we need information about risks versus benefits," he said. "There are some question marks, and they may change the risk-benefit ratio for some patients."

More information

There's more on statins at the American Heart Association.