Dr. Amy Tuteur is an obstetrician-gynecologist. She received her undergraduate degree from Harvard College and her medical degree from Boston University School of Medicine. Dr. Tuteur is a former clinical instructor at Harvard Medical School.

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JANUARY 28, 2009 11:08PM

Masturbation and prostate cancer

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  broken penis

It is difficult to imagine a health warning that would generate more fear than the announcement that masturbation leads to prostate cancer. Over 100 newspaper articles trumpeting the findings of a new paper on the subject have generated a wave of embarrassment and concern. That’s why it is important to analyze the paper very carefully to determine whether the evidence supports the authors’ claims. In my judgment, the paper has some very serious drawbacks that render its conclusions suspect.

The paper is titled Sexual activity and prostate cancer risk in men diagnosed at a young age. The paper only looked at a subset of men with prostate cancer, the 25% who are diagnosed before age 65. It is unclear why they chose to look only at this group and whether they believe there are any differences in prostate cancer occurring before age 65 and prostate cancer occurring after.

The way the study was conducted (the methodology) raises questions about the validity of the conclusions. The study is a case-control study, in which men with prostate cancer were compared to a control group of similarly aged men without cancer. According to the Oxford Centre classification of studies, a case control study is among the weakest forms of study, rating a 3 on a scale of 1-5; the two lower grades apply to descriptions that make no comparisons and to opinions.

This is also a retrospective study, meaning that the participants were asked to recall events that took place as many as 45 years before. Not surprisingly, these types of studies are often weakened by inability to properly recall details.

Finally, this is a very small study, looking at only 400 men with prostate cancer and 400 controls. A smaller study is less likely to generate valid results.

What were the authors expecting to see? The authors were hoping to determine if there is a relationship between sexual activity and the risk of developing prostate cancer before the age of 65. They looked at two types of sexual activity, masturbation and sexual intercourse.

What would such a relationship look like? In general, if a relationship exists, you would expect to see a “dose-response” effect. In other words, if increased sexual activity increased the risk of prostate cancer, you would expect that the lowest sexual activity levels would lead to the lowest risk, moderate levels of activity would be associated with moderate risk, and high levels of activity would be associated with high levels of risk.

What did the authors find? They found that there was no relationship between overall sexual activity and prostate cancer risk. The proportion of men with low, medium and high frequency of sexual activity were equal.

It’s difficult to publish a study that doesn’t show anything, so the authors went back and reworked their data. First, they looked at the relationship of sexual activity in each decade (20’s, 30’s, 40’s, 50’s) to the risk of developing prostate cancer before the age of 65. There was a suggestion that increased sexual activity in the 20’s was correlated with an increased rate of prostate cancer, but that relationship did not hold for any other decade. In fact, increased sexual activity in the 50’s was actually correlated with a decreased rate of prostate cancer

Then they further sub-divided the data into sexual intercourse frequency and masturbation frequency per decade. There was no relationship between sexual intercourse frequency in any decade and risk of prostate cancer before age 65.

Finally, they looked at the relationship between masturbation frequency per decade and the risk of prostate cancer before age 65. There was no relationship there, either BUT they noticed that low frequency of masturbation in the 20’s and 30’s was associated with a higher rate of prostate cancer, but masturbation in the 50’s was associated with a lower rate of prostate cancer.

What should we conclude from this? We should conclude that there is no overall relationship between sexual activity (whether intercourse or masturbation) and risk of developing prostate cancer before age 65. The few, random associations that appeared in the data are almost certainly anomalies, reflecting the small sample size, and the limitations inherent in any case-control studies. These findings are consistent with multiple previous studies that showed both positive and negative associations, as well as no association at all. The fact that there is no consistent pattern among all the studies taken together further reinforces the conclusion that there is no relationship between sexual activity and risk of prostate cancer.

That’s not what the authors decided to conclude, however. They chose to assume that the random associations they found were real, and not artifacts. They provide no explanation for why or how masturbation could increase the risk of prostate cancer in some decades and also decrease it in other decades, while at the very same time intercourse had no effect at all.

Does masturbation increase the risk of prostate cancer? There is no evidence in this paper that it does, and, a survey of previous papers on the topic provide no evidence of a consistent relationship of any kind. The conclusions of this paper are weak and unjustified, and the publicity campaign waged by the authors and publishers is disingenuous at best, if not outright irresponsible.

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I might have been in the control group of this survey. No cancer, as far as I know, but my prostate is on its 3rd pair of glasses.
Oh, thank God, I don't have to give up one of my favorite activities -------------------------------------------------- reading your blog! LOL
I think the issue you might want to discuss from
this dis-credible study is how studies like it have
historically given Big Pharma patent-extensions
without having to spend hundreds of mllions
in research to conduct legitimate trials for newer
indications. One might shrug of the insufficient
responsibilities toward lesser-known diseases with
possible curative measures that sit on shelves for
years while many die without ever knowing they

"lesser-known diseases with possible curative measures that sit on shelves for years while many die without ever knowing they

Such as?

Is there any evidence that drug companies are withholding treatments that they know are effective?
Dear Amy, thanks for bringing some good old fashioned reason to bear on the subject.

Interestingly, there was an Australian study a couple of years back linking LACK of masturbation at an earlier age to increased prostate cancer risk (90% of the male population were silently relieved...).

Also, what about masturbation alongside intercourse (not an uncommon occurence)? And what is the qualitative difference?

Wolfgang Schneider:

"And what is the qualitative difference?"

There's no difference physiologically. As far as the the difference in quality goes, that's a matter of individual opinion, I guess.
Oh thanks God!

I feel so much better now! :)
Such false conclusions truly are irresponsible, which makes the article not funny at all. The illustration you chose to use, however, is hysterical... in a very grim and frightening sort of way. Sheesh!
Please help me understand something. Assuming that intercourse and masterbation achieve the same outcome (no pun) for the individual, what is this study saying? Is it a frequency issue or physiology issue?

"The illustration you chose to use, however, is hysterical... in a very grim and frightening sort of way."

The found hundreds of potentially appropriate stock photos, but when I saw this one, I knew it was the one! It is meant to evoke a primal fear, and the publicity for the scientific paper traded on this same fear.

"Such false conclusions truly are irresponsible"

Unfortunately, science has become a business. Scientists must demonstrate that they provide "value" for the research dollars they spend, and, therefore, have incentives to make startling claims and hire publicists to spread the word.

The truth is that this study showed nothing, absolutely nothing. You can't publish that, though. So the investigators "sliced and diced" the data in every possible way until they found something to write about. The fact that it is almost certainly an artifact did not stop them from making a claim that was sure to get lots of publicity.

"what is this study saying? Is it a frequency issue or physiology issue?"

It's not surprising that there is confusion on this point; what the authors are saying and what the data shows are two different things.

The authors are saying that there is an association with masturbation and prostate cancer. Masturbating in your 20's increases the risk of prostate cancer, but masturbating in your 50's decreases the rate of prostate cancer. Not only does that make no sense, it isn't supported by the actual data in the study. Because of the small sample size, relatively weak methodology and inconsistent findings, the "associations" that the authors found are almost certainly artifacts. Were the study to be repeated with larger numbers (making the results more accurate), the purported associations would disappear.
I'm almost surprised that someone hasn't used the term, "Onanism." Our concepts of illness (and health) are always arrived at in a social/sociological context. Someone wanted to believe this and went looking for indicators. Was his Bible open to the thirty-eight chapter of Genesis, I wonder? And what's the payoff to whom to believe that "This is what women are for"?
When I saw the picture I was afraid you were going to tell me it was going to fall off. I'm glad to know that's not going to happen.

Now if you can prove my mother wrong and tell her I'm not going to go blind please.

BTW, my PSA is 0.7, but I still got the finger!
Okay, so I clicked the link to just read it. I'm not doing much, as you can tell from my posting, so I have the time.

What a shock. They want $43.08 plus tax to read it. They must have to refund the research grant.
Being alive causes prostate cancer because the control group of living people are the only ones who get it. Being dead frees one from the risk of prostate cancer.
I think the authors really missed the question here; they should have looked into the masturbation history comparing the frequency of masturbation of each cohort''s partners. Its truly unfortunate that the lay press picks up on bogus "studies" like this. Its bad enough that professionals have to wade thru inconsequential mental masturbatory studies to find real information, but tragic that the lay public who have little understanding of the science involved are assaulted with the bogus information.

I've always thought that masturbation was a (usually) solitary pursuit, not something one did in scientific publications.
Good nwes! Sry s har d typng wtih one hnad
Just want to say that you are really too, too hilarious with your serious, medical article posts and no matter what "new" sophomoric, snide or idiotic things your detractors come up with in their petty, adolescent jealous piques at your success in writing so many popular (well read) posts and many "Picks", they just CAN NOT touch are straight faced funny Amy!
This photo is off the chart funny by the way.
Just the fact that I'm still alive disproves their theory.
This study here shows the exact opposite:
This study involves over 2000 people. From the article: "They found those who had ejaculated the most between the ages of 20 and 50 were the least likely to develop the cancer.

The protective effect was greatest while the men were in their 20s. "
check this study peoples
Did they check whether the men in the control group had a predisposition to cancer ie there was already a family history? If my memory is correct then this is the biggest risk factor.
I suppose, given the statistics that men are almost as much at risk from Prostate Cancer (I believe) than women are from breast cancer, and that men don't get screening in the same way as the screening offered to women (I can imagine it's not an option having been subjected to the latter.Eeven the strongestof men would whimper at the pressure!) Anyway, I am guessing that PC is a bit of a medical hot potato (if you'll pardon the analogy) so any kind of research would get the thumbs up.
You are missing the point. Frequent regular masturbation is often indicative of the his sex drive associated with high testosterone levels. High testosterone levels may correlate with increased prostate cancer risk. The masturbation does not cause the cancer, and may in fact have a protective effect later in life.
Does it count if I masturbate in my wife?
what a hack ! We can go to and look this up ourselves

"This study involves over 2000 people. From the article: "They found those who had ejaculated the most between the ages of 20 and 50 were the least likely to develop the cancer.

The protective effect was greatest while the men were in their 20s."

And that's just one of many studies that showed very different findings.
jon a:

"Frequent regular masturbation is often indicative of the his sex drive associated with high testosterone levels. High testosterone levels may correlate with increased prostate cancer risk."

Frequently? How frequent is this association?
jon a:
Possibly, I don't know if testosterone levels have a link with prostate cancer. However, the "point" wasn't missed, because THIS study didn't look at testosterone levels. Only self-reported sexual activity levels. If it was a study that HAD looked at the levels, and Amy had posted something like this, then you could say she missed the point. But the authors were never trying to make the point you are, so your response is somewhat irrelevant to this study :-)
"it was a study that HAD looked at the levels, "
Just to clarify, when I said "levels" here, I was speaking of testosterone levels, not sexual activity levels. Sorry.
Moreover, a study released in April of last year found exactly the opposite.

Masturbation 'cuts cancer risk'
"Men could reduce their risk of developing prostate cancer through regular masturbation, researchers suggest. They say cancer-causing chemicals could build up in the prostate if men do not ejaculate regularly."
Breaking :

Men who lie about masturbation frequency less likely to develop Prostate cancer.

So, to quiet a bit the calls of "BAD SCIENCE", this is how the research behind this paper most likely transpired...

There's some literature that suggests that there may be a link between frequency of ejaculation and prostate cancer, but the data aren't clear. These guys decided they'd like to look into it.

To get the best data, you would enroll thousands of adolescent boys in your study, track their ejaculatory habits for 50 years, and see what happens. But no grant funding organization on the planet will fund that without some pretty strong preliminary data. Also, the investigators will probably be dead in 50 years. So they do a pilot study.

In this pilot study they recruit several hundred men, and get their information. Now, contrary to popular opinion, small sample sizes can be very informative. The problem is that in order to reach statistical significance the differences between groups have to be very large. So if the variable in question makes only a small difference you are unlikely to be able to detect it in a statistically significant way.

So these guys got some statistically significant data, but nothing overwhelming and probably not what they hoped for. It's enough to keep the question open that something might be going on, but certainly not enough to get anyone to fund that 50 year study. So they publish in a crappy, low-impact journal (British Journal of Urology? Seriously?) and life goes on. In a sane world the paper is completely ignored...
Good call, Amy. Well reasoned. The last thing not discussed. Within their pre-selected groups the question might arise (humour) as to, "Does a precancerous condition create a greater urge for ejaculation. " We are talking hormones and a hormone producing site and a hormone using or producing growth. All bets are off. Which came (humour) first, the chicken or the egg?

My beloved grandmother once told me that masturbation would lead to hairy palms, blindness, slow urination and a substitute for true affection....eventually she was right.
I hadn't heard about this study, and I'm glad you pointed it out. I'm also glad your analysis showed us that the study didn't show what it said it showed.

Thanks. I'm going to come back to your site.
Well done. This sort of thing has a long history, which I cover a bit in my related post over at Psychology Today. I've linked to yours. If you're interested, stop by:
Well I read some accounts of this study and was very encouraged to see they found some slight protective effect from masturbating more at a later age. All right by me (I'm 54). I can go along with that for the good of my health.

However what no-one, especially the sensationalist media, has pointed out is the authors of the study did say all the effects were marginal, showing me they had done due diligence on statistical analysis, taking into account their small sample size. This was really a paper about "We did a small study, which may show some significance, so give us some more money for a bigger one". A good fraction of papers in all fields of science can be summarized in the same way!
Woops ignore second comment above, the subject was covered by Amy, and by Sarah Soper. I seem to suffer from premature posting. Probably lackof/too much intellectual masturbation in my 20s.

BTW Amy said "The truth is that this study showed nothing, absolutely nothing. You can't publish that, though." You ought to see my Masters dissertation and the three thoroughly lightweight papers my supervisor squeezed out of it!
Ha! Need to send this one to the boyfriend.
But it reinforces the idea that people shouldn't play with their 'dirty parts'...

Like Woody Allen said: Masturbation is sex with someone you really care about...
Thank you for this very useful discussion Amy. It was both thoughtful and very well written. You deserve a wider audience.

I knew there must be SOMETHING good about turning 50 . . . . . .
Goodness. You could make the case that masturbation leads to baldness, or obesiety, or spontaneous combustion. You'd have a more reliable study if you used eunuchs.
Funny...I have had my own scientific theory about masturbation and sex and overall health. If you don't use it, you lose.

My study would go on to show that when you generate a lot of energy to your sexual organs, you keep them active and happy - kinda charged up, like a battery. Boy, this doesn't sound scientific at all...but guess what? I betcha mine is more right than theirs! I betcha.
In the previous four decades of my life, almost every time I would fall asleep with a stimulating problem in mind, I would invariably wake up with the solution in hand. No cancer so far, but often overworked metacarpals.
Thanks for restoring some sanity to this, and many other, medical issues.

While I'm generally supportive of the role and function of our mass news organizations in this country, it is sometimes disappointing that they so frequently misunderstand - and thus misreport - the true meaning of medical, scientific, and technical developments. Perhaps in an attempt to boost their audience they tend to sensationalize reports that are best understood and explained by detached experts.

Salon's Patrick Smith has for several years admirably performed this role in relation to aviation news stories. Thank you for doing a similar thing with medicine.
P.J. O'Rourke, I thought you were gonna tell us that you started growing hair on her palms! You werewolf you.