When I was young, I remember my grandfather’s worsening arthritis gradually limiting his ability to get around and enjoy the things he used to. He actually had a positive attitude about the situation, but one time he came as close to complaining as I can recall. “Getting old,” he said, “is not for sissies.”

For many men, getting old sneaks up on them in the form of dropping testosterone levels. Studies show that in men 40-70 years old, total testosterone diminishes at a rate of 0.4% annually, and free testosterone shows a more pronounced decline of 1.3% per year.^[i] This may not sound fearsome, but over time the potential consequences loom like cautionary childhood tales of the big bad wolf.

Testosterone contributes to a man’s health and identity in many areas: metabolism, muscle strength, bone density, mental/mood functions, sexual function, energy levels, etc. Thus, low testosterone levels (low T) can severely affect the health of aging males, increasing the risk of diabetes, dementia, cardiovascular disease, and mortality.^[ii] You don’t have to be a sissy to recognize that low T can practically guarantee aging will be no fun.

Men of all ages depend on normal T levels for their health and vigor. Thankfully, testosterone therapy (TTh) is a safe and effective treatment for men diagnosed with low T blood levels.

However, prostate cancer (PCa) also relies on testosterone to drive its own energy, up to a certain point. In fact, patients diagnosed with advanced PCa are generally prescribed drugs that cut off the supply of testosterone, and/or block cancer cells from taking it up. This is called androgen deprivation therapy (ADT) because it deprives PCa of male hormones (androgens), the chief one being testosterone. ADT is not a cure, but for a while it stops PCa in its tracks.

This phenomenon led to a mistaken theory that testosterone could cause PCa. We now know that this is not the case, but in turn it led to the belief that once a PCa patient has had definitive treatment (e.g. surgery, radiation, or focal therapy) it would never be safe for him to have testosterone replacement therapy even if he had low T.

Low testosterone and prostate cancer treatment

While we have posted numerous blogs on the safety of testosterone therapy after treatment for localized prostate cancer, a newer review of the evidence was published in November 2025.^[iii]

After analyzing hundreds of journal articles, the authors chose 12 studies with solid research design. Based on the cumulative evidence, the authors concluded that testosterone therapy was “not associated with an increased risk of biochemical recurrence or cancer progression in any included study.” In other words, patients who had definitive prostate cancer treatment and who also had low T blood levels treated with replacement therapy had stable PSA levels, and some “showed lower recurrence rates in [replacement therapy] groups compared to controls.”

They concluded that post-treatment PCa patients who also have low T can be considered for T replacement therapy provided their PSA continues to be stable.

Just as male aging brings greater likelihood for lower T levels, it also brings higher incidence of newly diagnosed PCa. If the two conditions occur together, it’s reassuring to know that a) treatment for localized PCa is nearly 100% successful at 5 years, and b) after successful treatment, T replacement therapy can increase the chances of long-term general health and vitality. This is good news for prostate cancer patients.

NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.

References

[i] Wu FC, Tajar A, Pye SR, Silman AJ et al. Hypothalamic-pituitary-testicular axis disruptions in older men are differentially linked to age and modifiable risk factors: the European Male Aging Study. J Clin Endocrinol Metab. 2008 Jul;93(7):2737-45.
[ii] Gibson, J., George, M., Grice, P. et al. Testosterone replacement therapy following definitive treatment for prostate cancer: a scoping review of safety and efficacy. Int J Impot Res (2025).
[iii] Gibson, J., George, M., Grice, P. et al. Testosterone replacement therapy following definitive treatment for prostate cancer: a scoping review of safety and efficacy. Int J Impot Res (2025).