Low testosterone (Low T) is a common problem for men as they age. Testosterone levels peak in the early teen and adult years and then begin decreasing after age 30 at a rate of approximately 1% each year. The most common treatment for Low T is testosterone replacement therapy. Yet, recent media reports and publicized debates surrounding the potential association between prostate cancer and testosterone replacement have caused concern among men. Is there an association between testosterone supplementation and the subsequent development of prostate cancer?

A study earlier this year looked at the risk of developing prostate cancer from testosterone replacement. The study included over 1000 men with low testosterone who were receiving testosterone replacement therapy. They were followed for a median of 5 years. Eleven (1%) of the men were diagnosed with prostate cancer, much lower than then historically expected 7% incidence. There did not appear to be any increased risk of prostate cancer with testosterone replacement.

Another study this year looked at men with an established history of prostate cancer who were receiving injectable testosterone replacement therapy for low testosterone levels. This study reviewed 149,354 men, including 1181 that received testosterone therapy. They found no increase in prostate cancer mortality or overall mortality in the men receiving testosterone.

Androgen deprivation therapy – medication to ‘turn off’ testosterone – has been a longstanding therapy for advanced prostate cancer. Prostate cancer ‘feeds’ on testosterone, so this treatment causes prostate cancer to shrink, or at least suppresses it. This concept has led us to believe for decades that raising testosterone levels must cause a negative effect for men with prostate cancer. We are now instead coming to understand the ‘saturation model’. This model suggests that at the cellular level, the receptors on cancer cells that are stimulated by testosterone get ‘saturated’ at very low levels of testosterone. Above this low level, there is no added stimulation. Thus, even at high serum testosterone levels, there is no increased effect.

While this topic is still being investigated, it appears that testosterone replacement therapy may be safe and acceptable for men with a history of prostate cancer.

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