Prostate cancer may be linked to sex hormones
Men who are more sexually active in their 20s and 30s may run a higher risk of prostate cancer, research suggests.
The Nottingham University study quizzed 800 men on how often they had sex or masturbated.
Those who were most active while younger had more chance of developing cancer later in life.
The researchers said higher levels of sex hormones could lead to a bigger sex drive and the cancer, the journal BJU International reported.
Prostate cancer is the most common cancer in men in the UK, with well over 30,000 new cases diagnosed each year.
It affects the prostate gland, which is found close to the bladder and makes a component of semen.
The Nottingham team, led by Dr Polyxeni Dimitropoulou, recruited more than 400 men diagnosed with prostate cancer, then compared their answers to 409 men thought to be free of the disease.
As well as questions about how often they had been sexually active from puberty onwards, they were asked how many sexual partners they had had and whether they had been diagnosed with any sexual infections.
Roughly the same proportion of both groups, 59%, said they had engaged in sexual activity 12 times a month or more in their 20s, falling to 48% in their 30s, 28% in their 40s and 13% in their 50s.
Almost two-fifths of the prostate cancer group had had six female partners or more, compared with less than a third of the non-cancer group.
There was also a difference among the men who masturbated or had sex the most often, with 40% of men in the cancer group being sexually active 20 times a month or more in their 20s, compared with 32% in the non-cancer group.
The gap between the two groups narrowed as the men aged, suggesting that the difference was strongest at a younger age.
Dr Dimitropoulou said: "What makes our study stand out from previous research is that we focused on a younger age group than normal and included both intercourse and masturbation at various stages in the participants' lives."
He said that it was possible that higher levels of sex hormones in some men were both responsible for a high sex drive in their 20s and 30s, and for the development of prostate cancer later on.
"Hormones appear to play a key role in prostate cancer and it is very common to treat men with therapy to reduce the hormones thought to stimulate the cancer cells."
She said that the reasons why the connection between sexual activity and prostate risk appeared to diminish with advancing age was not clear, although other studies have suggested that sexual activity releases toxins from the gland.
John Neate, chief executive of The Prostate Cancer Charity, said that while the study was useful, its findings would need to be backed by more evidence before they could be accepted
He said: "The role of sexual activity is becoming an increasing focus for prostate cancer research but unfortunately this study does little to offer any practical advice to men wishing to reduce their risk of the disease.
"The study is retrospective, and asks men to complete a questionnaire about their sexual history.
"However, in relying on men to recall information from 20 or 30 years previously, it is likely that there will be some inaccuracy in the data collected as men either consciously or unconsciously forget some detail which could compromise their findings.
"The sample used in the study is also relatively small, making it difficult to draw any universal conclusions."