The foreskin and prostate cancer:

Yet another wonderful benefit of circumcision?

Do green jellybeans cause acne? As this cartoon neatly demonstrates, the claim that they might is hardly less plausible than recent media headlines suggesting that the foreskin causes cancer of the prostate, and concluding (quite illogically) that circumcision of baby boys is, therefore, a desirable measure of public and individual health. There are three issues here: (1) whether “lack of circumcision” does significantly increase the risk of cancer of the prostate; (2) the hyperbolic newspaper reporting of one small study which claimed that perhaps it did, even if only a little bit; and (3) even if this claim were true, whether circumcision of infants was a logical and ethically acceptable response.

Foreskin and risk of prostate cancer

The claim that the presence of the foreskin increases the risk of prostate cancer, and therefore that all men ought to be circumcised, was first made in the 1940s by a cranky American doctor called Abraham Ravich, who believed that the disease was less common among his Jewish patients than in others. He managed to get a couple of articles published in American medical journals (always so hospitable to anti-foreskin propaganda), and in his old age compiled and self-published a whole book, Preventing VD and Cancer by Circumcision, in which he extolled the Mosaic code as the key to good health and a long life. A series of subsequent studies failed to find any association between lack of circumcision and increased risk of prostate cancer, however, and in its 2010 policy statement on circumcision the Royal Australasian College of Physicians noted tersely: “This association [between lack of circumcision and prostate cancer] has not been consistent, and more recent reviews have failed to confirm it.” This is a polite way of saying that the claim of a connection is bullshit.

Just recently (March 2012) a paper in the American journal Cancer claimed that there was a slight difference in the incidence of cancer of the prostate between uncircumcised men and men who had been circumcised before their first sexual intercourse. The research was a retrospective case-control study of men who self-reported their circumcision status, sexual histories and some other information. There were 1754 men with prostate cancer and 1645 without prostate cancer in the study. Of the first group, 1207 (68.8%) were circumcised; of the second group, 1176 (71.5%) were circumcised – a difference of a mere 2.7%. This absolute difference was then translated by a series of statistical manipulations into a relative risk of 15%. As the Skeptical Scalpel points out, however, the relative risk of developing prostate cancer was not significantly different in circumcised and uncircumcised men until the researchers looked at those who had been circumcised after their first episode of sexual intercourse. The number of men who had been circumcised after their first sexual encounter was only 68 (3.9%) of the men with prostate cancer and 41 (2.5%) of those without. Although the relative risk reduction was 15%, the confidence intervals were too wide (73% to 99%) to have much significance.

Most importantly, this is only a relative risk reduction, not an absolute risk reduction, and it thus of no relevance to the question of whether men ought to get themselves circumcised, much less whether boys ought to be circumcised.

A further weakness of the study is that it did not control for race or age – important issues, as African American men have double the rate of prostate cancer compared with whites and an overall circumcision incidence of only only 43%, and because the likelihood of prostate cancer rises sharply with increasing age. In addition, the study relied on self-report of circumcision status, which is wildly unreliable. It is, in short, a clinically unimportant finding based on self-report. The real questions are how such a poorly designed study got through peer-review and then published, and why it has been hyped so irresponsibly by the media.

See further discussion at Skeptical Scalpel

As Circumstitions points out, if those members of the study population who were circumcised after their sexual debut had not been merged with those never circumcised, the figures would have no significance at all. The much vaunted 15% reduction in relative risk amounts to a 2.7% reduction in absolute risk. The age-adjusted risk of prostate cancer for Caucasians in the United States is 150 per 100,000 person-years, or 0.0015 per year. The lifetime risk is about 72 times this, 0.108 or 1 in 9.25. Circumcision reduced this risk in only 2.7% of those with prostate cancer in this study, with 71.5% of controls circumcised. If this is adjusted up to 100% circumcision the reduced risk would affect a mere 3.77% of those with prostate cancer. The overall Absolute Risk Reduction would then be 0.108x0.0377 or 0.0040716. This means that TWO HUNDRED AND FORTY-FIVE babies would need to be circumcised to prevent one (old) man from getting prostate cancer. This would be quite absurd for many reasons, not least because of the cost.

The rabbi was wrong: Media hype misrepresents findings of prostate-circumcision study

It is truly amazing how any study that appears to show the foreskin in a bad light gets worldwide publicity, when journal articles critical of circumcision and statements against the practice from responsible medical authorities are ignored. Of course the media seized on this study, with the usual wild headlines: “Circumcision Cuts Prostate Cancer Risk” (Scientific American); “Circumcision reduces prostate cancer risk” (UPI); “Circumcision Linked to Lower Risk for Prostate Cancer, Study Finds” (Yahoo News); and best of all, “Males of the Mideast Rejoice: Circumcision Reduces Prostate Cancer” (Asian News International) or, even more ridiculous, "The rabbi was right: Prostate cancer prevention from birth" (Bradenton Herald). It will be observed that all these news reports are from circumcising cultures, naturally pleased that science appears to be confirming their traditional wisdom.

The last headline is particularly misleading, because it was not the rabbis who introduced circumcision to the Jewish religion, but the priests during the period of Temple Judaism, around 600 BC. What the rabbis introduced in the early Christian period was a new phase to the rite – metsitsah, in which the mohel (ritual circumciser) was required to suck the blood from the wounded penis after cutting off the foreskin. Needless to say, it would be hard to imagine anything more unhygienic, or more likely to spread disease, and there can be little doubt that devotion to metsitsah has been responsible for the deaths of countless Jewish babies over the centuries. The practice was largely abolished by Jewish reformers in the late nineteenth century, though it survives among some ultra-orthodox communities – notably in New York, where there have been several recent cases of babies dying from herpes infection after being circumcised by orthodox mohels.

What is even more bizarre about the scaremongering media coverage is that this latest study did not suggest even circumcision as a means of further lowering the risk (already quite small) of prostate cancer, but was most interested in a related question: the contribution of infection with human papilloma virus (HPV) to the risk of developing prostate cancer. There is a widely held belief that circumcised men are less likely to be infected with HPV, a view based largely on studies in Africa, but not confirmed by studies in the developed world; the most recent study, by Van Buskirk et al , found no difference. The whole sorry exercise seems to be just another chapter in the long history of the demonization of normal male anatomy.

This cartoon is a perfect representation of how the media reports circumcision studies

Prostate cancer issue not relevant to debate about infant circumcision

But even if the results of this study were valid, and circumcision did reduce the risk of a male developing prostate cancer by 15%, it would not be an argument for prophylactic circumcision of infants or boys. There are three main reasons for its irrelevance. (1) Although cancer of the prostate is one of the most common cancers affecting males, it still affects quite small numbers, and quite unpredictably; the risk factors appear to be age, race (or other genetic factors), smoking and exposure to HPV (through sexual intercourse with an infected partner.) The small numbers and risk reduction, as Circumstitions points out, are not sufficient to warrant general circumcision as a precaution against such a remote threat. (2) Cancers increase in frequency as people get older; an ageing population automatically means more cancers, irrespective of other factors, as the replication functions of bodily cells break down as we get older and wear out. It would be both illogical, unethical and highly cost-ineffective to circumcise over 200 babies now in order to prevent prostate cancer in one of them in 60 or 70 years time. Who knows what additional curative and preventive options we may have at our disposal by then?

(3) Since HPV is acquired sexually, we can say that to some extent prostate cancer is a sexually transmitted infection. But since infants and children are not sexually active, they are at zero risk of STIs, protection against which does not become an issue until boys grow up and become sexually active. Even then, it is only those who engage in high risk behaviour who are at risk of infection. The only policy consistent with evidence-based medicine and medical ethics, therefore, is to leave boys’ foreskins alone until they are mature enough to understand the medical issues and possible effects of circumcision, advise them of the risks of unsafe sex and other high risk behaviour, alert them to the protective options, and allow them to make up their own minds about how they wish to manage them. The automatic assumption that circumcision means circumcision of (non-consenting) infants or young boys is based on the tacit understanding that very few adult males, or boys who have discovered the delights and pleasures of their foreskin, would volunteer to have it cut off. But if the average adult would refuse circumcision, it would clearly be a violation of bioethical principles to coerce a child, merely because he was too young to put up effective resistance. Men are perfectly entitled to prefer to run a slightly greater risk of prostate cancer in old age in return for more fun and a better sex life in youth; some would prefer the other option, but the essential point is that circumcision is the individual male’s right to choose. It is not a decision to be made by others, no matter how well-meaning: his penis, his decision.

See further discussion on “Let the foreskin owner decide” page

Plenty of sex, better nutrition and  more exercise mean a healthier prostate?

Other studies suggest that more sex, better nutrition and adequate physical exercise will reduce risk of prostate cancer.

1. Plenty of sex

Douglas Fox, Masturbating may protect against prostate cancer, New Scientist, 16 July 2003

It will make you go blind. It will make your palms grow hairy. Such myths about masturbation are largely a thing of the past. But the latest research has even better news for young men: frequent self-pleasuring could protect against the most common kind of cancer. A team in Australia led by Graham Giles of The Cancer Council Victoria in Melbourne asked 1079 men with prostate cancer to fill in a questionnaire detailing their sexual habits, and compared their responses with those of 1259 healthy men of the same age. The team concludes that the more men ejaculate between the ages of 20 and 50, the less likely they are to develop prostate cancer.

The protective effect is greatest while men are in their twenties: those who had ejaculated more than five times per week in their twenties, for instance, were one-third less likely to develop aggressive prostate cancer later in life. The results contradict those of previous studies, which have suggested that having had many sexual partners, or a high frequency of sexual activity, increases the risk of prostate cancer by up to 40 per cent. The key difference is that these earlier studies defined sexual activity as sexual intercourse, whereas the latest study focused on the number of ejaculations, whether or not intercourse was involved. The team speculates that infections caused by intercourse may increase the risk of prostate cancer. “Had we been able to remove ejaculations associated with sexual intercourse, there should have been an even stronger protective effect of other ejaculations,” they suggest. “Men have many ways of using their prostate which do not involve women or other men,” Giles adds.

Macho exaggeration

Giles accepts the possibility that the men who completed the questionnaires could have lied about their habits. But he doubts this skewed the results, since questions about masturbation are unlikely to evoke the same macho exaggeration as questions about, say, number of sexual partners. But why should ejaculating more often cut the risk of prostate cancer? The team speculates that ejaculation prevents carcinogens building up in the gland. The prostate, together with the seminal vesicles, secretes the bulk of the fluid in semen, which is rich in substances such as potassium, zinc, fructose and citric acid. Generating the fluid involves concentrating these components from the bloodstream up to 600-fold - and this could be where the trouble starts. Studies in dogs show that carcinogens such as 3-methylcholanthrene, found in cigarette smoke, are also concentrated in prostate fluid. “It’s a prostatic stagnation hypothesis,” says Giles. “The more you flush the ducts out, the less there is to hang around and damage the cells that line them.”

Sexual repertoire

His findings suggest an intriguing parallel between prostate cancer and breast cancer, as recent studies indicate that lactating reduces a woman’s risk of breast cancer, perhaps because this also flushes out carcinogens. Alternatively, ejaculation might induce prostate cells to mature fully, making them less susceptible to carcinogens. “All these mechanisms are totally speculative,” cautions breast cancer expert Loren Lipworth of the International Epidemiology Institute in Rockville, Maryland. But if the finding is confirmed, future health advice from doctors may no longer be restricted to diet and exercise. “Masturbation is part of people’s sexual repertoire,” says Anthony Smith, deputy director of the Australian Research Centre in Sex, Health and Society at La Trobe University in Melbourne. “If these findings hold up, then it’s perfectly reasonable that men should be encouraged to masturbate,” he says.

Source: Douglas Fox, Masturbating may protect against prostate cancer, New Scientist, 16 July 2003


G.G. Giles et al, Sexual factors and prostate cancer, BJU International 92 (3), August 2003, 211-216

OBJECTIVE   To assess whether prostate cancer might be related to hormone levels and, by inference, to differences in sexual activity.

PATIENTS, SUBJECTS AND METHODS   In a case-control study of men with prostate cancer aged < 70 years at diagnosis and age-matched control subjects, information was collected on two aspects of sexual activity; the number of sexual partners and the frequency of total ejaculations during the third to fifth decades of life.

RESULTS   There was no association of prostate cancer with the number of sexual partners or with the maximum number of ejaculations in 24 h. There was a negative trend (P < 0.01) for the association between risk and number of ejaculations in the third decade, independent of those in the fourth or fifth. Men who averaged five or more ejaculations weekly in their 20s had an odds ratio (95% confidence interval) of 0.66 (0.49–0.87) compared with those who ejaculated less often.

CONCLUSIONS   The null association with the number of sexual partners argues against infection as a cause of prostate cancer in this population. Ejaculatory frequency, especially in early adult life, is negatively associated with the risk of prostate cancer, and thus the molecular biological consequences of suppressed or diminished ejaculation are worthy of further research.

2. Better nutrition and more exercise reduce cancer risk

Hot on the heels of the Cancer report comes a study in the Medical Journal of Australia which found that better nutrition and more exercise can significantly reduce the risk of many cancers, including prostate cancer. The abstract reads as follows:

Objective: To estimate the number of cancers to be diagnosed in 2025 that could be prevented solely due to changes in diet and physical activity.

Design and setting: We used an Australian population-based cancer database to estimate the total number of cancers to be diagnosed in 2025, by applying published age- and sex-specific population projections to current cancer incidence rates, and multiplying the projected numbers of cancers by estimates of population-attributable fractions.

Main outcome measures: Projected number of preventable cancers that would be diagnosed in 2025.

Results: Our projections suggest that there will be about 170 000 Australians diagnosed with cancer in 2025. This represents an increase of about 60% on the 2007 incidence. Almost 43 000 of these cancers (low estimate, 42 295; middle, 42 657; high, 43 990) could be prevented through improvements to diet and physical activity levels, including through their impact on obesity. It is likely that this is an underestimate of the true figure. The most preventable cancer types in 2025 were estimated to be bowel cancer and female breast cancer (10 049 and 7273 preventable cases, respectively).

Conclusions: About 25% of cancers, or about 43 000 cancers in 2025, can potentially be prevented through improvements in diet and physical activity. It is imperative that governments, clinicians and researchers act now if we are to reduce the significant future human and financial burden of cancer.

There is wide variation in the preventability of different kinds of cancer by diet and exercise, with cancer of the oesophagus at the top (72%) and cancer of the prostate at the bottom (16%). But a 16% absolute reduction in the number of prostate cancer cases is a far more impressive result than 15% relative risk reduction - and achieved by far more agreeable means.

Peter D. Baade, Xingqiong Meng, Craig Sinclair and Philippa Youl, Estimating the future burden of cancers preventable by better diet and physical activity in Australia, Medical Journal of Australia 196, 19 March 2012

Further criticism of "lack of circumcision-prostate cancer" link

David Smith from Norm-UK criticises latest prostate cancer speculations  (Youtube video)

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