Men with low levels of testosterone are at higher risk of dying from cancer when they are older, new research shows.

Researchers led by University of Western Australia Professor Bu Yeap found that men who had low testosterone earlier in life were 18 per cent more likely to die from cancer years later.

They were also at higher risk of being diagnosed with non-fatal cancer.

The research, published in the journal Lancet Healthy Longevity, analysed long-term data from more than 26,000 men involved in 11 studies from Australia, Europe and the US.

Analyses of sex hormones in blood samples taken from young men were matched to cancer outcomes in the same men as they aged.

The hormones under scrutiny included testosterone, dihydrotestosterone (DHT), sex hormone-binding globulin (SHBG) and luteinising hormone — which is made by the pituitary gland to stimulate the testes to make testosterone.

Professor Yeap said the international Androgens in Men Study aimed to find out if the concentration of sex hormones in the men’s blood was related to their risk of being diagnosed with, or dying from, cancer in the future.

“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,” he said.

Professor Yeap said the normal range in young, healthy men was usually between 10 and 30 nanomoles per litre, with levels tending to be lower in older men.

Testosterone levels could also be affected by factors such as physical activity and body mass index, or by medical conditions such as diabetes.

“We saw that when baseline testosterone was below 8.6 nmol/L, subsequent cancer risk started increasing,” Professor Yeap said.

“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.”

However, the study found the risk of prostate cancer was not linked to low testosterone.

“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.

“We did find, however, that men with low levels of SHBG and luteinising hormone were at higher risk of prostate cancer.”

Professor Yeap said the findings did not mean that men should start taking testosterone supplements to reduce their risk of 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,” he said.

But Professor Yeap urged men who were low in testosterone to go to a doctor for a full check-up.

“It may not show any sign of testicular disease, but it might show other health issues or risk factors they need to address,” he said.

“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.”