Statins appear to boost radiotherapy's prostate cancer cure rate for high-risk patients, according to a new report, as evidence mounts for statins' anti-cancer abilities.

The retrospective study looking at more than 1,000 prostate cancer patients undergoing radiation and hormone therapy found slightly higher survival rates among patients with aggressive cancers who were taking the commonly prescribed cholesterol-busting drug.

In the study, published in this month's issue of the International Journal of Radiation Oncology•Biology•Physics, the researchers looked at the records of 1,681 prostate cancer patients who received high-dose (median 81 Gy) radiotherapy treatments, with slightly more than half also getting hormone therapy, between 1995 and 2007 at Memorial Sloan-Kettering Cancer Center in New York.

About one-fifth of the men (382) were also taking statins. And for those high-risk men consuming the medicine, technically known as 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, their drug regimen might have done more than lower their cholesterol levels.

For high-risk patients in the statin group, the five-year and eight-year tumor-control rates based on the prostate-specific antigen blood levels were 81 percent and 75 percent. For high-risk patients not taking the drugs, corresponding tumor-control rates were 68 percent and 58 percent, respectively. No statistically significant difference was found among prostate cancer patients with low- or medium-risk disease. Nor was any benefit seen in distant metastases-free survival.

"In all likelihood, for those patients who have low-risk disease, we don't see the effects of the statins to begin with, because the treatments themselves are very effective in terms of their ability to kill the cancers," senior author Dr. Michael J. Zelefsky, professor of radiation oncology and chief of brachytherapy services at Memorial Sloan-Kettering, told DOTmed News.

Zelefsky's research backs up a growing body of evidence for statins' ability to help prostate cancer patients survive, at least for those undergoing radiation therapy. A retrospective 2010 study of almost 700 men by University of Chicago researchers published in the Journal of Clinical Oncology also found statin use was associated with increased relapse-free survival.

In the current study, the researchers said there was no obvious confounding factor that would have linked statin-taking with another protective effect. "It appears that there is some kind of positive interaction between the statins, possibly the hormonal therapy, and the radiation therapy," Zelefsky said.

But the exact mechanism that could be causing this effect, if it's real, is unclear. Hypotheses for statins' anti-cancer activity cover a wide range. The drugs could kill cancer cells outright by triggering apoptosis or they could enhance the sensitivity of radiation so more cancer cells can be destroyed during treatment.

Whatever the case, it's still too early to start changing clinical practice, as the studies so far have all been retrospective. The researchers don't know, for instance, what the appropriate dose of statins would be, or what type to use. Zelefsky said it's important now to corroborate the findings with prospective, randomized controlled trials. In the meantime, he's continuing to follow up with the patients in the study and looking to work with national groups on getting a large, multicenter trial off the ground.

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