Men who have children through fertility treatments may be more at risk of prostate cancer, research suggests.
Scientists analysed more than a million men who fathered children between 1994 and 2014 in Sweden.
They found those who had children through IVF or other fertility treatments were up to 64 per cent more likely to develop the disease.
The exact link between prostate cancer and infertility is unclear. But the scientists said genetic ‘abnormalities’ on the Y chromosome may be to blame.
DNA deletions on this chromosome are known to cause male infertility, while genes on the same chromosome have been linked to prostate cancer.
Men who became fathers via fertility treatments may be more at risk of prostate cancer (stock)
The research, published in the British Medical Journal, was carried out by Lund University in Sweden and Medical University Sofia in Bulgaria.
‘Men who achieved fatherhood through assisted reproduction techniques… are at high risk for early onset prostate cancer’, the scientists wrote.
‘[They] thus constitute a risk group in which testing and careful long term follow-up for prostate cancer may be beneficial.’
Prostate cancer and male infertility are common, affecting 10 per cent and eight per cent of men in ‘Western societies’, respectively, the scientists wrote.
Some studies have linked poor sperm quality with an increased risk of prostate cancer.
However, others suggest men are less likely to develop the disease if they do not have children.
To learn more, the researchers analysed 1.18million fathers who had children for the first time between 1994 and 2014 in Sweden.
Reporting fertility treatment is mandatory in Sweden, with ‘coverage close to 100 per cent’, the scientists wrote. This data was linked to cancer and death registers.
The men were followed from the conception of their child until either a prostate cancer diagnosis, death or the end of the study on December 31, 2014.
Of the men who had children naturally, 3,244 (0.28 per cent) developed prostate cancer.
This is compared to the 77 (0.37 per cent) and 63 (0.42 per cent) who became fathers via IVF and intracytoplasmic sperm injection (ICSI), respectively.
ICSI involves doctors injecting a single sperm into an egg.
This is different to IVF, which mixes sperm with eggs and allows them to fertilise.
In Sweden, ICSI is mainly used in men with ‘significantly impaired semen quality’, the scientists wrote. Its use therefore suggests severe infertility.
Results revealed the men who became fathers via ICSI were 64 per cent more likely to develop prostate cancer, while those who had children by IVF were 33 per cent more at risk.
The men who had children via assisted reproduction were also 86 per cent more likely to develop the disease before 55, defined as early-onset.
Professor Allan Pacey, from the University of Sheffield, said: ‘There have been a number of studies over the past few years suggesting a diagnosis of male infertility might be a possible marker of future health conditions in men.
‘As such, it has been proposed male infertility might serve as a “canary in the coal mine” for men’s health.
‘This study is excellent, and adds further evidence to the ‘canary in the coal mine’ theory by showing Swedish men who became fathers using techniques of assisted reproduction are at increased risk of prostate cancer later in life.
‘It is important to be clear this is not because the techniques of assisted reproduction go on to cause prostate cancer, but probably because the two have a common cause in some way.
‘Perhaps all men who are diagnosed with a fertility problem in their 20’s and 30’s should be given a leaflet explaining what this might mean for them in their 50’s and 60’s’.
The researchers argue screening should be considered among this group of men, who appear to be at a higher risk of the disease.
Experts argue, however, this would be ‘difficult to justify’.
Writing in a linked editorial, a team from Hammersmith Hospital said: ‘In the absence of a plausible mechanism of action or proof of causation, justifying screening for prostate cancer in all infertile men is difficult.
‘However, further research on the possible future complications of male infertility would be welcomed by patients and will help clinicians to counsel all infertile men about their future health.’
There is no screening programme for prostate cancer in the UK or US.
A blood test that looks for a protein called ‘prostate-specific antigen’ (PSA) has been suggested.
However, healthy cells also produce PSA, leading to small amounts in the bloodstream even in men without cancer.
PSA levels can rise if the prostate enlarges, which may be an indicator of a problem. However, cancer may not necessarily be to blame. Levels also rise with age.
Furthermore, up to 15 per cent of men with prostate cancer have normal PSA levels, which can cause cases to be missed, according to the NHS.
The PSA test can also pick up on cancers that are slow growing and do not cause symptoms or shorten life.
For many prostate-cancer sufferers, treatment is unnecessary, with doctors recommending ‘watchful waiting’.
A positive PSA test could cause patient anxiety, prompting them to have treatment. In many cases, the side effects outweigh the benefits, with some being left incontinent and impotent.