Why Low Testosterone Could Be an Early Warning Sign of Cancer

A major international study involving more than 26,000 men has uncovered a troubling connection between testosterone and cancer. Men with the lowest testosterone levels had an 18 percent higher risk of dying from cancer than those with the highest levels.

The findings, highlighted by ScienceDaily, suggest that unusually low testosterone could be an early warning sign of broader health problems. But researchers emphasize that the hormone itself hasn’t been shown to cause cancer—or prevent it.

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The Testosterone Level That Raised Concerns

Researchers from the University of Western Australia analyzed 11 long-running studies across Australia, Europe, and the United States, comparing earlier hormone measurements with cancer outcomes years later.

The research, published in The Lancet Healthy Longevity, identified increasing cancer mortality risk when testosterone fell below 8.6 nanomoles per liter, approximately 248 nanograms per deciliter.

“We saw that when baseline testosterone was below 8.6 nmol/L, subsequent cancer risk started increasing,” said Bu Yeap, PhD, a professor at the University of Western Australia’s Medical School.

“This suggests low testosterone is an important biomarker, so it’s possible that looking at testosterone levels could help us identify men who might do poorly if they get cancer down the track.”

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The Prostate Cancer Finding Was Different

Despite longstanding questions about testosterone and prostate cancer, researchers found no association between naturally occurring testosterone levels and prostate cancer incidence.

Instead, lower concentrations of two other hormones—sex hormone-binding globulin and luteinizing hormone—were associated with greater prostate cancer risk.

That distinction matters because hormone levels alone cannot establish whether someone will develop cancer.

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Why Doctors Aren’t Recommending Testosterone Therapy

The findings don’t mean testosterone replacement prevents cancer.

“While we’ve shown low levels are associated with increased risk, we haven’t got any evidence yet that actually giving men testosterone will reduce that risk,” Yeap said.

He also cautioned that unexpectedly low testosterone deserves medical attention.

“It could be a wake-up call and encouragement for men to engage in more healthy lifestyle behaviours, and to get regular, holistic checkups to stay on top of their health.”

For men concerned about declining testosterone, the takeaway is straightforward: Discuss abnormal results with a physician rather than treating a single hormone measurement as a cancer prediction—or a reason to start testosterone therapy.

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This story was originally published by Men’s Journal on Nov 8, 2026, where it first appeared in the Health section. Add Men’s Journal as a Preferred Source by clicking here.