October 20, 2014 — A study in rodents has found a higher risk of prostate cancer associated with testosterone therapy.
The study was published in Endocrinology by Maarten Bosland, PhD, a professor of pathology at the University of Illinois.
Dr. Bosland decided to investigate the prostate cancer risk in rodents. The rats were split into three groups: one group received only injections of a carcinogen, one group received only testosterone, and one group received both testosterone and a carcinogen.
Surprisingly, none of the rats given the carcinogen developed prostate cancer. However, 10-18% of rats on testosterone developed prostate cancer. The highest risk was seen in rats given both testosterone and a carcinogen — 50-71% developed prostate cancer, even on low doses of testosterone. Higher rates of prostate cancer were associated with higher doses of testosterone.
Dr. Bosland concluded:
“Testosterone was shown to be a weak complete carcinogen and a strong tumor promoter for the rat prostate in this study. These findings have potential significant public health implications for the use of testosterone therapy in men.”
It is unknown if men on testosterone have a higher risk of prostate cancer. Larger and longer studies are needed to fully investigate the risk. However, this study is a concerning warning sign. It is also reminiscent of studies linking estrogen therapy with breast cancer in women, which essentially ended the widespread practice of prescribing estrogen to alleviate symptoms of menopause.
In the last decade, testosterone therapy has recently boomed in popularity. Although millions of men are now using testosterone for “age-related hypogonadism,” the long-term risks are unknown. The FDA is now investigating studies linking testosterone with heart attacks, stroke, and other side effects.