Very low testosterone tied to higher risk of dying from cancer in men

Men with very low testosterone were more likely to die from cancer later in life, according to a large international study of more than 26,000 men published in the journal Lancet Healthy Longevity.¹ Men whose testosterone was in the lowest fifth of the range had an 18% higher risk of dying from cancer than men in the highest fifth, even after the researchers allowed for age and other health factors.¹ The researchers stress that the result is a link between two things, not proof that low testosterone causes cancer deaths.¹

What happened

The work comes from the Androgens In Men Study (AIMS), an international collaboration led by Professor Bu Yeap at The University of Western Australia.¹ The group pooled data from 11 long-running studies of men in Australia, the United States and Europe.¹

The researchers looked at hormone levels in blood samples collected earlier in the men’s lives. They then compared those levels with cancer diagnoses and deaths recorded over the following decades.¹ Besides testosterone, they measured dihydrotestosterone (DHT, a stronger form of testosterone), sex hormone-binding globulin (SHBG, a protein that carries sex hormones in the blood) and luteinizing hormone, which is made by the pituitary gland in the brain and tells the testes to make testosterone.¹

“What we saw was that if a man had low testosterone levels - in the lowest one-fifth compared to the highest one-fifth of the range - their subsequent risk of dying from cancer was higher, even after allowing for age and other health-related factors.”

That is how Professor Yeap described the main result.¹

The evidence so far

The team also looked for a level below which risk started to climb. “We saw that when baseline testosterone was below 8.6 nmol/L, subsequent cancer risk started increasing,” Professor Yeap said.¹ For comparison, he said testosterone in healthy younger men usually ranges from 10 to 30 nanomoles per liter (nmol/L), and levels generally fall with age.¹

The link was not the same for every type of cancer.¹ Prostate cancer showed a different pattern. A man’s natural testosterone level was not linked to his risk of developing prostate cancer.¹ Instead, men with low levels of SHBG and luteinizing hormone were at higher risk of prostate cancer.¹

This question matters because lowering testosterone is an established treatment for prostate cancer.¹ “Since reducing testosterone levels is a treatment for prostate cancer there’s always been a question of whether the amount of testosterone your own body makes relates to your risk of prostate cancer but based on our findings there’s no evidence they are related,” Professor Yeap said.¹

What it does not show yet

This is an observational study. It followed what happened to men over time; it did not give anyone a treatment. The release notes that the results show an association and do not establish that low testosterone itself causes cancer.¹

Other things can affect testosterone. Levels can be influenced by body mass index and physical activity, and medical conditions such as diabetes can change them too.¹ That makes it hard to tell whether low testosterone plays a role in cancer outcomes or simply travels alongside other signs of poorer health.

The study also does not show that raising testosterone helps. “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,” Professor Yeap said.¹ He emphasized that the findings should not be read as a reason to take testosterone supplements to prevent cancer.¹ Instead, the researchers suggest that unexpectedly low testosterone could be a prompt for doctors to look further into a man’s health.¹

The summaries Biohack read do not give risk figures for each separate cancer type, so it is not yet clear from them which cancers drive the overall 18% figure.

Who is behind it

The study was led from The University of Western Australia as part of the AIMS collaboration.¹ The same group published an earlier analysis in 2024 in the journal Annals of Internal Medicine, with Bu Yeap as corresponding author.² The news release on the new study did not describe who funded it or whether the authors have ties to companies that make testosterone products, and Biohack did not see those details in the sources it read.

How it fits the field

The new result builds on the group’s earlier work. In 2024, the team combined 11 studies with more than 24,000 men and found that low testosterone was linked to a higher risk of death from any cause.² Men with testosterone below 7.4 nmol/L had a higher risk of dying from any cause, and men below 5.3 nmol/L had a higher risk of dying from heart and blood vessel disease.² Those studies measured testosterone with mass spectrometry, described as the most accurate way to measure it, and an accompanying editorial from the University of Washington praised the analysis for its rigorous methods.²

Views on testosterone and prostate cancer have also been shifting. Mohit Khera, a urology professor at Baylor College of Medicine, said in 2023 that he was once taught testosterone was dangerous because it might raise prostate cancer risk, and that thinking has since changed.³ He noted that 2018 American Urological Association guidelines tell clinicians to inform patients of the absence of evidence linking testosterone therapy to developing prostate cancer.³ He also said there have been no randomized placebo-controlled trials (studies comparing a treatment with a dummy treatment) of testosterone therapy in men whose prostate cancer has spread.³

Low testosterone has also been tied to how prostate cancer behaves after diagnosis. A study of 924 men being watched closely for early prostate cancer, rather than treated right away, found that those with low testosterone had a 61% higher risk of their cancer becoming more aggressive.⁴ That study looked back at existing records, and its authors called for new studies to confirm the result.⁴

Testosterone treatment itself is used for men with low levels and symptoms. A review of 14 studies with 1,388 men, posted as a preprint that has not yet been checked by other scientists, found treatment was linked to better results on measures such as erectile function, fatigue and body composition.⁵ Its authors said randomized trials showed smaller effects than observational studies and called for longer, high-quality trials.⁵ That review did not look at cancer deaths.

The question matters on a large scale. One projection published in the journal Cancer estimated that cancer deaths among men worldwide could grow from 5.4 million in 2022 to 10.5 million by 2050.⁶

What to watch next

The key open question is whether testosterone is a cause or a marker. Professor Yeap described low testosterone as a possible biomarker that could help identify men who might do poorly if they get cancer later.¹ Testing that idea would require studies that check whether using testosterone levels changes how men are monitored, and trials that test whether raising testosterone changes cancer outcomes. The researchers say they do not yet have evidence that giving testosterone lowers the risk.¹

Watch also for more detail on the prostate cancer finding, since the links with SHBG and luteinizing hormone rather than testosterone itself point to a different hormone pattern for that disease.¹