Drugs that many men with prostate cancer might already be taking -- cholesterol-lowering statins -- may help extend their survival if they have a "high-risk" form of the disease, new research suggests.
High-risk patients include men with high blood levels of prostate specific antigen (PSA) and a "Gleason score" of 8 or more. Gleason scores are a calculation used to gauge prognosis in prostate cancer. Men with a high Gleason score may develop difficult-to-treat cancers.
Prior research had suggested that statins and the diabetes drug metformin (often prescribed together) have anticancer properties. However, it hasn't been clear which of the two drugs is the bigger cancer-fighter, or whether either might help against high-risk prostate cancer.
To help answer those questions, a team led by Grace Lu-Yao of the Sidney Kimmel Cancer Center--Jefferson Health, in Philadelphia, tracked data on nearly 13,000 high-risk prostate cancer patients. All were diagnosed between 2007 and 2011.
The study couldn't prove cause and effect, but it found that statins, taken alone or with metformin, did seem associated with an increase in survival.
Men who took both statins and metformin had higher median survival (3.9 years) than those who took statins alone (3.6 years), metformin alone (3.1 years), or those who did not take either drug (3.1 years).
The study was published Feb. 8 in the journal Cancer Medicine.
"Both metformin and statins have been associated with longer life in prostate cancer patients, yet because they are commonly prescribed together, no study we know of has looked at these two medications separately," Lu-Yao said in a center news release. She's associate director of population science at the center.
"With respect to prostate mortality, metformin plus statin was associated with a 36 percent reduction in risk of death followed by statins alone," Lu-Yao added.
The study also found that those who took one of three types of statin -- atorvastatin, pravastatin or rosuvastatin -- had longer survival than those who did not take any statins. A similar benefit was not seen with a fourth statin, lovastatin.
Because prostate cancer thrives on testosterone, patients often receive treatments that reduce levels of male hormones (androgens). The new study found that among patients who received such therapies, those who took atorvastatin had a longer median time to prostate cancer progression than those who didn't take statins.
It's not clear why such effects were limited to atorvastatin, Lu-Yao said, but it appears to have the best "bioavailability" of the statin drugs and lingers longest in the body.
The research team believes that, based on the existing evidence, a clinical trial should be conducted to assess the effectiveness of statins and the combination of statins/metformin in extending survival of prostate cancer patients.
Two prostate cancer specialists unconnected to the new study agreed that the findings show promise.
"It appears that there may be a place in the treatment of prostate cancer for statins," said Dr. Elizabeth Kavaler, a urology specialist at Lenox Hill Hospital in New York City. "However, we are not yet at a point where we can use the data to direct patient care."
She believes testosterone may be key here. According to Kavaler, higher cholesterol levels promote higher levels of androgens, which in turn help encourage the growth of prostate cancer. Statins may help slow that process, Kavaler explained.
Dr. Manish Vira is vice chair for urologic research at The Arthur Smith Institute for Urology in New Hyde Park, N.Y. He agreed that the findings are encouraging, and noted that "a dozen actively recruiting clinical trials using either metformin or a statin in prostate cancer treatment" are already underway.
The American Cancer Society has more on prostate cancer.
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