The finding can't prove that statins lower the risk of prostate cancer, and the authors note that there's still some controversy about if and how statins affect a man's risk of getting prostate cancer.
But the new study is "helping to build a story that there may be something there," said Dr Stephen Freedland, who studies prostate cancer at the Duke University School of Medicine.
Still, the men in the study weren't randomised, and so might harbour hidden differences that could influence their cancer risk, added Dr Freedland, who wasn't involved in the new research.
"There's probably something about them that (explains why) they were taking statins," he said, such as being proactive about their health.
According to the American Cancer Society, one in six men gets prostate cancer at some point in his life and one in 36 dies from it.
In the new investigation, Dr Nelly Tan and colleagues at the Cleveland Clinic reviewed the medical records of more than 4,000 men who had a biopsy for prostate cancer at their institution between 2000 and 2007. All of those men were biopsied because doctors found elevated PSA levels or an enlarged prostate during an exam.
About 1,000 of those men were taking statins, and about 3,000 weren't, according to their records.
After their biopsies, 55% of men taking statins were diagnosed with prostate cancer, compared to 58% who weren't taking statins. When the researchers took into account age, weight, and other differences between statin users and non-users, they confirmed that difference.
Men taking statins were also less likely to have aggressive forms of prostate cancer - especially those who had been taking the drugs for more than five years, the authors report in The Journal of Urology.
Dr Tan and her colleagues note that they couldn't take other diseases such as diabetes and heart disease into account, or other medications men were taking. And because their study only consisted of men who were already having a prostate biopsy done, they don't know if the results are generalisable.
However, Dr Tan said that previous studies have shown the same effect in the general population, and that "the literature is pointing towards a link" between statin use and a lower overall risk of prostate cancer. And the evidence is convincing, she said, that statins protect against more aggressive prostate cancer.
The association could be due to the cholesterol-lowering effects of statins, Dr Freedland said. Cholesterol, he explained, is a nutrient for tumours, and if there's not enough cholesterol, they can't grow.
It's also possible, Dr Tan said, that statins could affect other pathways in the body linked to prostate cancer, outside of cholesterol levels.
She said that the results reflect one more possible benefit of taking statins, which are generally prescribed to protect against heart disease, although she added that men shouldn't start taking them just to stave off prostate cancer.
One of the study's authors also works with companies that market statins, according to the Cleveland Clinic Website.
Dr Freedland said that the link between cholesterol and prostate cancer means that statins might not be the only way for men to lower their cancer risk. (Reuters Health/ May 2011)
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