TRT and Prostate Cancer: The Myth That Won't Die (and the Studies That Killed It)

Since the 1940s, the medical establishment has warned that testosterone fuels prostate cancer. This belief was so deeply embedded that many doctors reflexively refused TRT for any man over 50, regardless of symptoms. The fear was straightforward: if you raise testosterone, you feed any prostate cancer cells that might be lurking.

The evidence tells a different story. And understanding how the myth originated helps explain why it persisted for so long despite growing contradictory data.

How the Myth Started

In 1941, Charles Huggins published work showing that castration (removing testosterone entirely) caused prostate cancer to regress, and that testosterone supplementation caused it to grow. This was groundbreaking cancer research that earned Huggins a Nobel Prize. But the conclusion that "testosterone causes prostate cancer" was an overextension of the data.

Huggins was studying men with advanced metastatic prostate cancer. His findings showed that testosterone is necessary for prostate cancer cells to proliferate — not that physiological testosterone levels cause cancer to develop in the first place. This distinction is critical.

The Saturation Model

Abraham Morgentaler's saturation model, developed in the 2000s, provides the modern understanding. Androgen receptors in the prostate have a finite binding capacity. Once these receptors are saturated — which occurs at relatively low testosterone levels (approximately 150-250 ng/dL) — additional testosterone has no further effect on prostate cell growth.

This explains why castrate-level testosterone (near zero) causes cancer regression, but raising testosterone from low-normal to high-normal doesn't increase cancer risk: the receptors are already saturated in both cases. It's analogous to adding water to an already-full sponge — the extra water runs off.

What Large Studies Show

Multiple large epidemiological studies and meta-analyses have found no association between endogenous testosterone levels and prostate cancer risk. Men with naturally high testosterone don't get more prostate cancer than men with naturally low testosterone. The TRAVERSE trial — the largest TRT safety trial ever — found no increase in prostate cancer incidence in the testosterone group.

Current Endocrine Society guidelines state that TRT does not increase the risk of developing prostate cancer. They do recommend monitoring PSA (prostate-specific antigen) during TRT, not because testosterone causes cancer, but because the standard of care includes surveillance.