One of the most persistent fears surrounding testosterone is that higher levels increase the risk of prostate cancer. Mention testosterone replacement therapy and it usually doesn’t take long before someone brings up the prostate. The basic idea sounds logical enough. Prostate cancer is sensitive to androgens. Lowering testosterone can slow the progression of prostate cancer. Therefore, higher testosterone must increase the risk of prostate cancer. The problem is that biology doesn’t always work according to simple linear logic.
Much of our fear regarding testosterone and prostate cancer can be traced back more than 80 years to groundbreaking work performed by Dr. Charles Huggins in the 1940s. Huggins demonstrated that dramatically lowering testosterone could cause metastatic prostate cancer to regress. This was an incredibly important discovery and eventually earned him a Nobel Prize. The problem wasn’t the research. The problem was what was extrapolated from it.
If removing testosterone caused prostate cancer to regress, the assumption became that increasing testosterone must cause prostate cancer to grow. From there it wasn’t much of a leap to the belief that men with higher testosterone were at greater risk of developing prostate cancer in the first place. Those aren’t necessarily the same thing. There is an enormous difference between saying that an established prostate cancer can utilize testosterone and saying that higher testosterone causes prostate cancer.
Think about it this way. If you remove virtually all testosterone from a man’s body, many androgen-dependent processes are going to change dramatically. That doesn’t mean increasing testosterone indefinitely produces an equally dramatic effect in the opposite direction. This distinction is at the heart of what has become known as the androgen saturation model.
The old way of thinking about testosterone and the prostate was essentially linear. If a little testosterone stimulates the prostate a little, more testosterone must stimulate it more. Therefore, the higher your testosterone level, the greater the prostate stimulation and presumably the greater the cancer risk. That sounds reasonable. It just doesn’t appear to be how the system works.
Androgen receptors in prostate tissue appear to become substantially saturated at relatively modest concentrations of testosterone. When testosterone is extremely low, increasing it can have a meaningful effect on prostate tissue. But once sufficient testosterone is present to substantially saturate those receptors, increasing circulating testosterone further doesn’t necessarily produce proportionately greater stimulation.
Imagine filling a glass with water. Going from an empty glass to a half-full glass obviously makes a significant difference. Going from half-full to full makes another difference. But once the glass is full, continuing to pour water doesn’t somehow make the glass twice as full. This may help explain why bringing a hypogonadal man’s testosterone from 200 ng/dL to 700 or 800 ng/dL doesn’t appear to produce the dramatic increase in prostate cancer risk that the old model would predict.
It also raises an obvious question. If high testosterone were a major driver of prostate cancer, why is prostate cancer overwhelmingly a disease of older men? Men generally have their highest testosterone levels when they’re young. Testosterone then tends to decline with age. Yet prostate cancer incidence moves in exactly the opposite direction. That alone doesn’t prove testosterone is harmless. Cancer is far too complicated for that. But it certainly doesn’t fit very well with the simplistic idea that more testosterone equals more prostate cancer.
This brings us to probably the most important distinction in the entire discussion: existing prostate cancer and developing prostate cancer are two different questions. Prostate cancer can absolutely be androgen-sensitive. This is why androgen-deprivation therapy remains an important treatment for men with certain forms of prostate cancer. But treating an existing cancer by removing something it needs does not prove that normal levels of that substance caused the cancer to develop.
Unfortunately, those two ideas were treated as though they were interchangeable for decades. The result was tremendous fear surrounding testosterone replacement therapy. Men with legitimate testosterone deficiency were often told that increasing their testosterone might essentially throw gasoline on the prostate and eventually produce cancer. We now have decades of additional research, and that dire prediction simply hasn’t materialized.
One of the strongest recent pieces of evidence came from the large randomized TRAVERSE trial, which included more than 5,000 men with hypogonadism. Researchers prospectively followed prostate-related outcomes in men receiving testosterone compared with men receiving placebo. In appropriately screened men, there was no statistically significant increase in overall prostate cancer or high-grade prostate cancer in the testosterone group.
Testosterone treatment did produce a somewhat greater increase in PSA, particularly early in treatment, but this shouldn’t be surprising. PSA itself is androgen-responsive. If you take a man with very low testosterone and restore his testosterone to a normal physiological level, some increase in prostate activity can occur. An increase in PSA does not automatically mean testosterone has caused prostate cancer. PSA is an important marker that should be monitored, but it isn’t a cancer diagnosis.
Even the American Urological Association states in its testosterone-deficiency guidelines that patients should be informed that there is an absence of evidence linking testosterone therapy to the development of prostate cancer. That’s a pretty dramatic departure from what many men were told about testosterone for decades.
Of course, whenever an old medical belief starts falling apart, there’s a tendency for people to run too far in the opposite direction. The old argument was that testosterone causes prostate cancer. The opposite extreme would be to claim that testosterone has absolutely nothing to do with prostate cancer and that men using testosterone never need to think about their prostate. Neither position makes sense.
Prostate tissue responds to androgens. Some established prostate cancers are highly androgen-sensitive, and there are men for whom testosterone therapy may not be appropriate without careful evaluation by a knowledgeable physician. We also don’t have randomized controlled trials following men on TRT for 30 or 40 years. No responsible person should pretend that we know everything there is to know about long-term testosterone therapy. What we can say is that the evidence we have today does not support the old claim that restoring testosterone to healthy physiological levels causes prostate cancer. That’s an important distinction.
I’ve discussed hormone optimization for many years, and I’ve never believed the goal should be to push testosterone as high as humanly possible. More isn’t always better. The objective should be to maintain testosterone in a healthy, optimal range while paying attention to the entire hormonal picture rather than obsessing over one isolated number.
That philosophy is also behind products such as Aggressive Strength Testosterone Booster (ASTB) and Estrogen Control (EC). They were never intended to be substitutes for blood work, medical evaluation, or appropriate treatment. The goal with ASTB has always been to support healthy natural testosterone production, while EC was designed to support healthy estrogen metabolism. Neither is about blindly driving one hormone as high or as low as possible. Hormones work together, and maintaining an appropriate balance is far more important than chasing an impressive number on a lab report.
Whether someone is using nutritional support, TRT, or neither, the same basic principle applies: assess, monitor, and make adjustments based on the individual. For men using TRT, that means looking beyond testosterone alone. Estradiol, hematocrit, SHBG, symptoms, cardiovascular markers, PSA, and overall prostate health can all provide useful context. Hormone optimization should involve monitoring, not guesswork.
Supporting healthy hormone levels and recklessly pushing hormones far outside physiological ranges are two very different things. If you’re on TRT, get appropriate blood work. Establish a baseline PSA before beginning treatment when appropriate and follow it over time. Pay attention to significant changes rather than becoming obsessed with a single number. Monitoring something because it’s important is very different from assuming testosterone is inherently dangerous.
I think the testosterone and prostate cancer story also illustrates something much larger about medicine. An observation can be correct while the conclusion drawn from it is incomplete. Charles Huggins was correct that dramatically reducing testosterone could cause metastatic prostate cancer to regress. His discovery changed medicine and deserved the recognition it received. What became problematic was turning that observation into a universal equation: less testosterone equals less prostate cancer, therefore more testosterone equals more prostate cancer.
Human physiology rarely works that neatly.
More than 80 years later, we have the benefit of considerably more research, a much better understanding of androgen receptors, the androgen saturation model, decades of clinical experience with testosterone replacement therapy, and large randomized trials. The picture that has emerged is far more nuanced.
Testosterone matters to the prostate. That doesn’t mean testosterone causes prostate cancer.
There is currently no convincing evidence that restoring testosterone from deficient levels into a healthy physiological range substantially increases a man’s risk of developing prostate cancer. That’s a very different message from the one men heard for much of the last century.
It is also a good reminder of something I have learned repeatedly over the years when researching hormones, nutrition, supplementation, and health: Never confuse a long-standing belief with a proven fact.
Sometimes today’s “common knowledge” is little more than yesterday’s hypothesis that nobody bothered to question.
