June 27, 2013 | by Darrin Joy
A flurry of recent ads have pitched treatments for low testosterone (“low T”) as a way to counter the waning energy and libido levels experienced by many aging men, but the intimidating litany of potential side effects includes a possible increased risk of prostate cancer. New City of Hope research sheds some light on this potential dilemma.
First, some background on prostate cancer and hormones: Prostate cancer occurs most often in men over 65 years old. The disease usually is driven by male hormones, especially testosterone. But testosterone declines as the body ages, meaning libido and energy suffer.
A study led by City of Hope’s Jeremy Jones, Ph.D., assistant professor in the Department of Molecular Pharmacology, suggests a reason those lower levels occur at the same time as an increased risk of prostate cancer — testosterone levels in the prostate don’t necessarily correlate with what’s in the rest of the body.
Jones and his City of Hope colleagues looked at male hormones, called androgens, in rodents. They compared the level of androgens in the rodents’ blood with that in their prostate tissues and found roughly the same amount of testosterone in their prostate tissue regardless of the amount in blood.
In other words, the prostate seems to be able to maintain testosterone levels, even if the rest of the body can’t. The scientists think this means androgen-producing cells have a growth advantage in the prostate when the body’s testosterone falls. And it may be that those hormone-producing cells are more likely to develop into cancer.
They found a clue in the way prostate cancer becomes resistant to hormone-reducing therapy, often called “chemical castration,” which is the main treatment for metastatic prostate cancer.
“One of the main mechanisms of resistance to chemical castration is that the cancer increases androgen production,” Jones said. The team thought normal tissue might also do that as men age, and it seems they may be right.
“We haven’t proven it, but we have shown that the enzymes used to produce androgens are upregulated” in the prostate as the body’s testosterone falls, Jones said. The findings are strong evidence that the scientists are on the right track.
For men considering treatments to boost their testosterone levels, the findings are provocative.
“The warnings are there because testosterone drives prostate cancer, so if you already have it, it could get worse,” Jones said.
But if you don’t have it, you might actually reduce your risk with low T treatments, Jones said. “For men with no disease, no one’s ever really seen an increase in prostate cancer.” In fact, there actually seems to be a decrease in incidence for men using the treatments, though Jones is quick to point out that there haven’t been any studies to confirm those observations.
Obviously more study is needed and, most men would agree, the sooner the better.
Additional authors on the study, published online in the Journal of Molecular Endocrinology, were Ye Zhou, Ph.D., Maya Otto-Duessel, Ph.D., Miaoling He, Susan Markel and Tim Synold, Ph.D.
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