Older men with higher levels of free testosterone more likely to develop prostate cancer

New research finds older men with higher levels of free testosterone have an increased risk of prostate cancer. Australian researchers spent a decade exploring the testosterone-prostate cancer connection by comparing natural testosterone levels of men in their 70s and 80s, those with prostate cancer and without.     

"Men with late-onset prostate cancer had higher levels of testosterone," said Mount Sinai prostate cancer robotic surgeon, Dr. David Samadi. "The increased risk was seen in men with naturally high testosterone levels, as well as those taking testosterone hormone replacement therapy."

The knowledge of testosterone's role in prostate cancer is not new. Hormone therapy, or androgen deprivation therapy, is a widely used prostate cancer treatment option designed to slow the growth of the disease by suppressing testosterone. This study was initiated to learn more about how testosterone might trigger the onset of prostate cancer.

As part of The Health in Men Study (HIMS), researchers from The University of Western Australia discovered that men diagnosed with late-onset prostate cancer had testosterone levels that were 13 picomoles per liter of blood higher than those who did not develop the disease. An even greater testosterone increase was seen in men who developed lung cancer.

"We don't see a direct cause and effect in these findings," said Dr. Samadi, "but they do provide further evidence that a higher testosterone level could speed the disease's growth rate. That's something men with and without prostate cancer should carefully consider."

Testosterone therapy risk
While this study does not prove a direct correlation between testosterone replacement drugs and prostate cancer risk, it serves as yet another caution. Hormone replacement therapy can be prescribed to men with low libido, erectile dysfunction, and reduced energy level. "Some doctors are quick to recommend testosterone," says Dr. Samadi, "but testosterone isn't a cure-all and it isn't one-size-fits-all. Replacement testosterone can introduce risks that are not fully known. Prostate cancer might be one of them." 

Watchful waiting riskMen diagnosed with prostate cancer can opt to postpone treatment and monitor the disease in hopes it is slow growing enough to not cause damage. Many experts, including Dr. Samadi, believe this to be an unnecessary gamble as prostate cancer can spread quickly and without warning. The Australian study could add a new layer of concern to those who choose no treatment, or less aggressive treatment. "A higher testosterone level could kick otherwise slow-growing prostate cancers into high gear," Dr. Samadi pointed out, "There's no way to contain the disease without treatment."