Low Cholesterol May Help Prevent Cancer
TUESDAY Nov. 3, 2009 -- Low blood cholesterol levels reduce the risk not only of heart disease but also of cancer, two new studies show.
The findings should help ease longstanding fears that low cholesterol is associated with an increased risk of cancer, said Dr. Demetrius Albanes, a senior investigator at the U.S. National Cancer Institute, and an author of one of two reports in the November issue of Cancer Epidemiology, Biomarkers and Prevention.
"These results should help dispel any lingering thoughts that low cholesterol may help cause cancer," said Eric Jacobs, strategic director of pharmacoepidemiology at the American Cancer Society, who wrote an accompanying editorial.
Data from a study that has followed more than 29,000 Finnish men for 18 years showed both the reason for fears that low cholesterol levels raised the risk of cancer and the reason why those fears were unjustified, Albanes said.
Cholesterol levels below the generally recommended 200 milligrams per deciliter were associated with an 18 percent higher overall risk of cancer, but the increased risk applied only to cases diagnosed in the early years of the study. "The finding supports the idea that lower cholesterol levels are the results of undiagnosed cancers," Albanes explained.
And higher levels of HDL cholesterol, the "good" kind that protects coronary arteries, were associated with a 14 percent lower risk of all cancers over the entire length of the study, he said.
In addition, data on the more than 5,500 men enrolled in the Prostate Cancer Prevention Trial showed that those with cholesterol levels lower than 200 had a 59 percent lower risk of developing the most dangerous form of that cancer, said a second report in the same issue of the journal.
Low cholesterol levels were more likely to be seen in men whose prostate cancers had high Gleason scores, a measure of the disruption of the prostate gland's normal structure caused by the malignancy, the study found. Prostate cancers with the highest Gleason scores are regarded as the most difficult to treat.
Cholesterol levels had no significant effect on the overall incidence of prostate cancer in the study, said study leader Elizabeth Platz, co-director of the cancer prevention and control program at the Johns Hopkins Kimmel Cancer Center.
But the association between low cholesterol levels and a reduced incidence of aggressive disease "is a notable reduction which is not often seen for prostate cancer," she said.
It is still not known whether statins, which help prevent heart disease by lowering blood levels of "bad" LDL cholesterol, can reduce the risk of cancer, Albanes said.
"We did not collect information in detail on cholesterol-lowering efforts," Albanes said. "It may be premature to read from our findings that such efforts to actively lower cholesterol levels can achieve a cancer benefit. Our results don't speak to that point."
Nevertheless, "evidence continues to mount that the use of statins is inversely correlated with the risk of prostate cancer," Platz said.
But both agreed that further research is needed to both prove the point and identify the molecular mechanisms behind the association.
A guide to cholesterol is offered by the American Heart Association.
Posted: November 2009
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