You probably know testosterone as the hormone men blame for mood swings or a slow workout.
For most men, it's just a number on a lab report they rarely think about. That number may be telling you more than you realize.
An international team pooled data from more than 26,000 men. Those with the lowest testosterone levels had an 18 percent higher risk of dying from cancer than men with the highest levels.
The study was published in The Lancet Healthy Longevity in June 2026.
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The researchers combined 11 long-running studies from Australia, the United States, and Europe. Each participant had been followed for at least five years. The link held even after researchers accounted for age and other health factors.
Where the risk starts to climb
The signal appeared below a specific threshold. Cancer death risk started to rise when testosterone fell under 8.6 nmol/L. For context, healthy younger men usually land between 10 and 30 nmol/L.
Risk of being diagnosed with cancer went up at a slightly lower cutoff, around 7.3 nmol/L. Both figures sit well under what labs generally treat as the lower end of normal.
What the lead researcher says
The project is part of the Androgens In Men Study, led by Professor Bu Yeap, an endocrinologist at The University of Western Australia.
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"This suggests low testosterone is an important biomarker," Yeap said in the university's statement. "It's possible that looking at testosterone levels could help us identify men who might do poorly if they get cancer down the track."
A biomarker is a measurable signal in the body that can hint at future disease risk. It doesn't mean the hormone itself is causing cancer.
Prostate cancer was different
One cancer stood apart. Testosterone levels showed no link with prostate cancer risk in the data.
That matters, because lowering testosterone is a standard treatment for advanced prostate cancer.
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The new analysis suggests a man's natural testosterone level does not raise or lower his odds of being diagnosed with the disease.
Not a reason to start supplements
The study found an association, not proof that testosterone supplements would cut cancer risk. The researchers were explicit about this.
"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 told the University of Western Australia.
Testosterone therapy carries its own risks. It should only be considered with a doctor, based on symptoms and blood tests.
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If your reading comes back low at your next check-up, that is a reason to talk to your doctor about what might be behind it. It is not a reason to order supplements online.
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This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.