TRT and Prostate Cancer: Why the Warning Is Being Removed

If you've ever hesitated about starting testosterone therapy because of prostate cancer concerns, you're not alone. For decades, the idea that TRT could cause or accelerate prostate cancer has been one of the most powerful deterrents keeping men from seeking treatment — and one of the most common reasons doctors give for refusing to prescribe it.

The problem? The science doesn't support it. And the FDA is finally acknowledging that reality.

Where the Myth Came From

The belief that testosterone fuels prostate cancer traces back to 1941, when Dr. Charles Huggins published a groundbreaking observation: surgically castrating men with advanced prostate cancer caused their tumors to shrink. This discovery earned Huggins a Nobel Prize in 1966 and established the principle that prostate cancer is "androgen-dependent."

From there, the medical community made a logical — but ultimately flawed — leap: if removing testosterone shrinks prostate tumors, then adding testosterone must make them grow. This reasoning became medical dogma for over 60 years, embedded in medical school curricula, clinical guidelines, and FDA product labeling.

The problem is that the reasoning was incomplete. Huggins' work showed that prostate cancer responds to the removal of androgens. It did not show that adding testosterone to a man with normal or low-normal levels causes prostate cancer to develop or progress.

The Saturation Model: Why More T Doesn't Mean More Cancer

Starting in the 2000s, Dr. Abraham Morgentaler at Harvard Medical School began challenging the testosterone-prostate cancer dogma. His research introduced the "saturation model" — a concept that has fundamentally changed how scientists understand the relationship between testosterone and the prostate.

The key insight: prostate tissue has a finite number of androgen receptors. Once these receptors are saturated — which happens at relatively low testosterone concentrations (around 230-250 ng/dL) — additional testosterone has no further stimulating effect on prostate cells. Think of it like a sponge: once a sponge is fully saturated with water, pouring more water over it doesn't make it hold more.

This explains why castration (reducing testosterone to near zero) dramatically affects prostate cancer — you're going below the saturation threshold. But raising testosterone from, say, 250 ng/dL to 700 ng/dL has no additional effect on prostate cell growth, because the receptors were already fully occupied at the lower level.

What the TRAVERSE Trial Found

While the TRAVERSE trial was primarily designed to evaluate cardiovascular safety, it also provided the most definitive data ever collected on TRT and prostate cancer risk in a randomized, controlled setting.

Among 5,246 men followed for a mean of 22-33 months, testosterone therapy did not increase the risk of prostate cancer or high-grade prostatic disease compared to placebo.

This wasn't a secondary finding buried in a supplement — it was a pre-specified safety outcome that the trial was designed to detect. The result was unambiguous.

Additional support comes from a large study published in JAMA Network Open in 2023, which found no significant difference in prostate cancer incidence between TRT patients and placebo recipients among middle-aged and older men with hypogonadism.

As Dr. Franck Mauvais-Jarvis, professor of medicine at Tulane University and director of the VA hormone therapy clinic, summarized: "The bottom line is no, testosterone does not increase the risk of prostate cancer."

What the FDA Is Doing About It

At the December 2025 FDA expert panel, the removal of the prostate cancer warning was one of the least controversial recommendations. The panel's position was clear: the current labeling is not supported by contemporary evidence and should be updated.

The FDA had already removed the cardiovascular black box warning in February 2025 based on TRAVERSE data. The prostate cancer warning is expected to follow a similar path, likely within the next 12-18 months.

This matters because the warning on the label doesn't just affect patients — it affects how doctors practice. Many primary care physicians see "prostate cancer" on a drug label and understandably become cautious about prescribing. Removing this outdated warning will help more men access treatment that could improve their quality of life.

PSA Monitoring on TRT: Still Important

Removing the cancer warning doesn't mean abandoning prostate health monitoring. Here's the nuanced reality:

TRT does not cause prostate cancer. This is what the evidence shows.

TRT can raise PSA levels modestly. When you start testosterone therapy, your PSA (prostate-specific antigen) may increase slightly — typically within the first 3-6 months — then stabilize. This is a normal physiologic response, not a sign of cancer.

Monitoring still matters. A baseline PSA should be obtained before starting TRT, with follow-up testing at 3-6 months and annually thereafter. What doctors watch for isn't the absolute number, but the velocity — a rapid or sustained rise in PSA warrants further evaluation, regardless of whether you're on TRT.

TRT is not recommended for men with active prostate cancer. While TRT doesn't cause prostate cancer, exogenous testosterone could theoretically stimulate growth in a prostate that already harbors malignant cells below the androgen saturation threshold. Men with a current prostate cancer diagnosis should discuss their individual situation with their oncologist.

The Bottom Line

The fear that testosterone therapy causes prostate cancer was based on an 80-year-old extrapolation from castration studies — not on direct evidence from randomized controlled trials. Modern research, culminating in the TRAVERSE trial, has definitively shown that TRT at physiologic doses does not increase prostate cancer risk.

The FDA expert panel's recommendation to remove the prostate cancer warning reflects what the urology and endocrinology communities have increasingly recognized: this warning has deterred men from beneficial treatment based on outdated science.

If prostate cancer concerns have kept you from exploring TRT, this is the moment to revisit that decision with your healthcare provider — armed with the best evidence available.