New research presented this weekend at the National Cancer Research Institute (NCRI) Cancer Conference in Liverpool has concluded that men with naturally low levels of the male sex hormone testosterone are less likely to develop prostate cancer than those with higher blood levels of the hormone.
This research, carried out by scientists at the University of Oxford, looked at blood samples from around 19,000 men aged between 34 and 76, collected between 1959 and 2004. 6,900 of these men went on to develop prostate cancer. The scientists divided the men into 10 groups, depending on the level of testosterone in their blood, and compared this to prostate cancer risk.
What’s interesting about this research is that while low levels of testosterone were associated with decreased risk of developing prostate cancer, high testosterone levels were not associated with increased risk. This supports the theory that there are only so many androgen receptors (the proteins that bind testosterone to activate it, so that it can do its job) in the body. So once these are all ‘full up’ with testosterone, it doesn’t matter how much more testosterone is circulating in the blood, because it can’t bind to and activate a receptor. This would explain why high levels of testosterone don’t increase risk of developing prostate cancer, but low levels can lower it.
However, while this research gives some interesting clues about factors involved in causing prostate cancer in the first place – which will undoubtedly prove useful in working out how to one day prevent the disease from occurring – it also raised more difficult questions.
That’s because although men with lower levels of testosterone were less likely to develop prostate cancer, once they did, it was more likely to be an aggressive form of the disease. So far, we don’t have any answers as to why this might be, but it adds yet another layer of complexity to the mystery of prostate cancer development, and opens another avenue of investigation to the scientists set on unravelling these sorts of clues. It also suggests that testosterone levels alone will not hold the key to the causes of prostate cancer development, and that the link between male sex hormones and cancer development may well be more complicated than we previously imagined.
Dr Matthew Hobbs, Deputy Director of Research at Prostate Cancer UK said: “This research gives us some important clues about the role that testosterone might play in triggering prostate cancer. It’s particularly interesting that men in this study with the lowest levels of the hormone were less likely to get prostate cancer, but if they were diagnosed, it was more likely to be aggressive. This is clearly a complex effect and more research is needed to understand it.
“We still know too little about what causes prostate cancer cells to develop. We urgently need this knowledge to understand how we might prevent the disease in the future, which is why this is a key research priority for Prostate Cancer UK. Until we know more about the underlying causes of prostate cancer, it’s important that all men – and particularly black men, men with family history and men over 50 – are aware of their risk of prostate cancer and go to the GP if they have any concerns.”