All I have to say is: would the medical profession please pick a side and stick to it? Because this is all very confusing.
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....
So. More frequent sex and/or ejaculation in your salad days may be related to a more frequent incidence of prostate cancer. OK. Got it.
21:00 06 April 2004 by Shaoni Bhattacharya
Frequent sexual intercourse and masturbation protects men against a common form of cancer, suggests the largest study of the issue to date yet.
The US study, which followed nearly 30,000 men over eight years, showed that those that ejaculated most frequently were significantly less likely to get prostate cancer. The results back the findings of a smaller Australian study revealed by New Scientist in July 2003 that asserted that masturbation was good for men. In the US study, the group with the highest lifetime average of ejaculation - 21 times per month - were a third less likely to develop the cancer than the reference group, who ejaculated four to seven times a month.
Michael Leitzmann, at the National Cancer Institute in Bethesda, Maryland, and colleagues set out to test a long-held theory that suggested the opposite - that a higher ejaculation rate raises the risk of prostate cancer. "The good news is it is not related to an increased risk," he told New Scientist. In fact, it "may be associated with a lower risk."
"It goes a long way to confirm the findings from our recent case-control study," says Graham Giles, who led the Australian study. He praises the study's large size - including about 1500 cases of prostate cancer.
Furthermore, it was the first to begin by following thousands of healthy men. This rules out some of the biases which might be introduced by asking men diagnosed with prostate cancer to recall their sexual behaviour retrospectively....
...Or, frequent ejaculation is probably good for you and protects against prostate cancer.
...All-righty, then!
I would, I must confess, be more inclined to believe the earlier study, if only because it follows a much larger group of men. Both the US and Nottingham studies followed some men who were healthy to start with; the difference seems to be that the US study started with 30,000 healthy men and followed them for a very long time, while the Nottingham study started with roughly 400 healthy men and 400 prostate cancer survivors, and tried to figure out the differences between the two groups.
I must confess, I'm a bit puzzled as to why the Nottingham study did what they did. I mean, there's a very large study sitting out there that actually followed the men, rather than asking them questions about long-ago sexual activity. Apart from faulty recall, men lie about such things, even to researchers. Nobody wants to look like they were That Nerdy Guy, sitting at home not gettin' any. That said, I would assume that the actual lying would balance out between the studies, that it would have been accounted for. It's far more difficult to account for faulty recall, however; you're more likely to misremember things from 20 years ago. I would assume the first study also used some sort of questionnaire -- they're hardly likely to have pinned monitors to the people and followed them the whole time, noting, "Hey, excited heartbeat and temperature! Must be having sex!" Presumably, fresher memories would produce more accurate recall.
I wish I had access to the actual Nottingham study; it would be interesting to see how they accounted for the rather sharp differences between their study and the prior US and Australian studies, indicating almost -- but not quite -- precisely opposite conclusions regarding the protective effect of sex (or lack thereof, as the case may be). It's interesting as well to note that in the parts of the Nottingham study presented in the articles, it seems clear that they only studied heterosexual men -- which, in a study of 800 men on a sexuality-neutral topic like prostate cancer, seems like an odd bit of deliberate selection. Either that, or something like 20-80 of the men were, shall we say, fibbing.
The actual science aside, there are a couple of interesting aspects to this story. Both concern the media coverage. First, why did this story suddenly bubbled up everywhere this week, despite the fact that the study was published back in the November 2008 issue of the British Journal of Urology? And there's also the truly fascinating issue of the presentation, and what it may reveal about agendas here and there ... about which, more elsewhere.
Posted by iain at January 27, 2009 12:46 PM
