Circumcision and Prostate Cancer
The prostate is 20cm upstream from the foreskin, as the sperm swim. The notion that circumcision has any effect on prostate cancer seemed so outlandish that for 10 years, these pages have consigned it to the circumsitions, with the annotation "Dr Abraham Ravich". But in March 2012, it too was spread all over the media with headlines like "The rabbi was right: prostate cancer prevention from birth".
As usual, the case was much weaker than the hype, to the point of non-existence.
The source of the notion that circumcision prevents prostate cancer
was Ravich and Ravich. In 1942 Abraham Ravich, a NY urologist, published an article in the Journal of Urology reporting that among his patients, cancer of the prostate was far more common among Gentiles than Jews. He attributed this to circumcision. He believed that the cancer was viral in origin, with the familiar statements about foreskins.
They stressed "the importance of circumcision
as a public health measure".
Ravich A, Ravich RA. Prophylaxis of cancer of the prostate,
cervix and penis by circumcision. NY State J Med. 1951; 51:1519-21.
In 1973, aged 84 and retired in Miami, he published a book,
Preventing V.D. and Cancer by Circumcision, which included grandiose claims
about the "Mosaic Code".
A study by Kaplan found no significant differences in frequency of
circumcision between cases and controls in non-Jewish men. They
postulated a genetic cause for the difference between Jews and
Kaplan, G.W., O'Connor V.J. jr, The Incidence of Carcinoma of the Prostate in Jews and Gentiles (research letter) JAMA. 1966; 196(9):123-4.
Kaplan confirmed this conclusion in a 1977 article, "Cicumcision-An
Overview" in "Current Problems in Pediatrics."
Gibson reported that 20% of London prostate cancer patients had been
circumcised at birth, a percentage too high (higher than the baseline rate) to support a hypothesis
of protection being afforded by circumcision.
Gibson, E. Carcinoma of the Prostate in Jews and uncirumcised gentiles BJU 1954; 26:227-229.
Kaplan and Gibson specifically stated that their findings refuted those of Ravich and
McCredie reported an association between circumcision and prostate symptoms as measured by IPSS.
McCredie M, Staples M, Johnson W, English DR, Giles GG.
Prevalence of urinary symptoms in urban Australian men aged 40-69. J
Epidemiol Biostat. 2003; 6(2):211-8.
Oliver found no association between PSA (or anti-chlamydial titre)
and circumcision status. Yet they stated "lack of circumcision...[is]
associated with prostate cancer".
Oliver JC, Oliver RT, Ballard RC. Influence of circumcision
and sexual behaviour on PSA levels in patients attending a sexually
transmitted disease (STD) clinic Influence of circumcision and
sexual behaviour on PSA levels in patients attending a sexually transmitted
disease (STD) clinic. Prostate Cancer Prostatic Dis. 2001;
Lai found no correlation between circumcision status and incidence
of bacterial colonization in the prostate tissue. But asserted
"Uncircumcised men have a higher incidence of bacteriuria and
bacteremia following prostate needle biopsies".
Lai FC, Kennedy WA, Lindert KA, Terris MK. Effect of
circumcision on prostatic bacterial colonization and subsequent
bacterial seeding following transrectal ultrasound-guided prostate
biopsies. Tech Urol. 2001; 7(4):305-9.
Rosenblatt reported that risk estimates for prostate cancer
increased directly with the lifetime number of female sexual partners (trend p
<0.001) but not with male partners.
Rosenblatt KA, Wicklund KG, Stanford JL. Sexual factors and
the risk of prostate cancer. Am J Epidemiol. 2001; 153(12):1152-8.
Rotkin reported an excess of prostate cancer patients as compared
with controls had been circumcised at birth but had difficulty in
interpreting it since it ran contrary to his expectation.
Rotkin ID. Studies in the epidemiology of prostate cancer:
expanded sampling. Cancer Treat Rep. 1977; 61:173-80.
Jackson's comparison of prostate cancer patients and controls found
no apparent trend with regard to circumcision among other factors.
Jackson MA Kovi J, Heshmat MY et al. Characterization of
prostatic carcinoma among blacks: a comparison between a low
incidence area, Ibadan, Nigeria and a high incidence area, Washington, DC.
Prostate. 1980; 1:185-205.
Wynder stated "Circumcision: There was no significant difference
between the non-Jewish cancer and control groups in this regard".
Wynder EL Mabuchi K, Whitmore WF. Epidemiology of cancer of
the prostate. Cancer. 1971; 28:344-60.
Here is the abstract to the 2012 study:
Circumcision and the Risk of Prostate Cancer
Jonathan L.Wright, Daniel W. Lin and Janet L. Stanford
Several lines of evidence support a role for infectious agents in the development of prostate cancer (PCa). In particular, sexually transmitted infections (STIs) have been implicated in PCa etiology, and [some] studies have found that the risk of acquiring a STI can be reduced with circumcision. [Others have not.] Therefore, circumcision may reduce PCa risk.
Participant data collected as part of 2 population-based case-control studies of PCa were analyzed. Self-reported circumcision status, age at circumcision, and age at first sexual intercourse were recorded along with a history of STIs or prostatitis. Multivariate logistic regression was used to estimate the relative risk of PCa by circumcision status.
Data from 1754 cases and 1645 controls were available. Circumcision before first sexual intercourse was associated with a 15% reduction in risk of PCa compared to that of uncircumcised men (95% confidence interval [CI], 0.73-0.99). [FALSE. This was a comparison between circumcision before first intercourse and never-circumcised men plus men circumcised later.] This risk reduction was observed for cases with both less aggressive (odds ratio, 0.88; 95% CI, 0.74-1.04 [NOT SIGNIFICANT] ) and more aggressive (odds ratio, 0.82; 95% CI, 0.66-1.00 [barely significant] ) PCa features.
Circumcision before first sexual intercourse is associated with [weasel words] a reduction in the relative risk of PCa in this study population. These findings are consistent with research supporting the infectious/inflammation pathway in prostate carcinogenesis.
If those circumcised after sexual debut had not been merged with those never circumcised, any significance would be lost. There is a slight tendency towards an association between circumcision after sexual debut and prostate cancer, and it is this - not any benefit of early circumcision - that causes the claimed association. This cartoon satirizes the science being done here.
The 15% reduction in relative risk amounts to a 2.7% reduction in absolute risk. The age-adusted 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 the study with 71.5% of
controls circumcised. If this is adjusted up to 100% circumcision the
reduced risk would affect 3.77% of those with prostate cancer. The
overall Absolute Risk Reduction would be 0.108x0.0377 or 0.0040716. This means TWO HUNDRED AND FORTY-FIVE babies would need to be circumcised to prevent one (old) man from getting prostate cancer.
Other calculations give "only" 41 or 52 circumcisions wasted, but the whole exercise is beside the point when we are talking about preventing prostate cancers that develop 80 years from now - in the 2090s. It is as if people could have made appropriate decisions to prepare for the diseases of today - in 1932!
...the fact that men in the control group had not been diagnosed with prostate cancer does not mean that they do not have prostate cancer. It is unclear how many of them had undergone screening or prostate biopsies to determine whether microscopic disease was present. [Since they were obtained by a random telephone survey, probably very few.]
We know from autopsy studies that about 30% of the men may indeed have undetected prostate cancer. If that were the case here, it would certainly have an effect on the real difference in prostate cancer incidence in circumcised vs uncircumcised men.
- Dr. Gerald Chodak, Medscape Urology (with video) March 28, 2012
BJU Int. 2014 Mar 24. doi: 10.1111/bju.12741. [Epub ahead of print],
Circumcision and prostate cancer: a population-based case-control study in Montreal, Canada.
Spence AR1, Rousseau MC, Karakiewicz PI, Parent ME.
To investigate the possible association between circumcision and prostate cancer (PCa) risk, to examine whether age at circumcision influences the PCa risk, and to determine whether race modifies the circumcision-PCa relationship. [begging the question that there is such a relationship. Was this objective decided on after the race effect had been "found"?]
SUBJECTS AND METHODS:
PROtEuS, a population-based case-control study set amongst the mainly French-speaking population in Montreal, Canada, was used to address study objectives. The study included 1,590 pathologically confirmed PCa cases diagnosed in a Montreal French hospital between 2005 and 2009, and 1,618 population controls ascertained from the French electoral list, frequency-matched to cases by age. [So there was no assurance that the controls did not in fact have prostate cancer.] In-person interviews elicited information on sociodemographic, lifestyle and environmental factors. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) between circumcision, age at circumcision and PCa risk, adjusting for age, ancestry, PCa family history, PCa screening history, education, and history of sexually transmitted infections.
Circumcised men had a slightly lower risk, albeit not statistically significant, of developing PCa than uncircumcised men (OR 0.89, 95% CI 0.76-1.04). [What part of "not statistically signficant" do these researchers not understand?] Circumcision was found to be protective in subjects circumcised after the age of 35 (OR 0.55, 95% CI 0.30-0.98). [The statistical significance of this is marginal. This is contrary to Wright's study above, which found a very weak contrary "effect" for men circumcised after sexual debut.] A weaker protective effect was observed among men circumcised within one year of birth (OR 0.86, 95% CI 0.72-1.04 [since the 95% confidence interval crosses 1.0, this has no statistical significance.]). The strongest protective effect of circumcision was recorded in Black men (OR 0.40, 95% CI 0.19-0.86, p-value for interaction 0.02) but no association was found with other ancestral groups.
[They did not find any "protective effects" only (very weak) correlations. Black men amount to 9.1% of the population of Montreal, so only about 147 of their controls were black. This reduces the statistical significance of their "finding" accordingly.]
[Like so many other "circumcision and X" studies, this grasps at any straw for a protective effect, ignoring all other considerations or possibilities.]
Our findings provide novel evidence for a protective effect of circumcision against PCa development, especially to those circumcised after age 35; although, circumcision before the age of 1 may also confer protection. Circumcision appeared to be protective only among Black men, a group which has the highest rate of disease. Further research into the differences in effect of circumcision on PCa risk by ancestry is warranted, as is the influence of age at circumcision.
Dr Matthew Hobbs, Deputy Director of Research at Prostate Cancer UK
responded to the study saying:
“Although this study appears to show that circumcision after the age of 35 could reduce your risk of prostate cancer, the evidence presented is nowhere near strong enough that men should begin to consider circumcision as a way to prevent the disease. While the total sample studied was large, the number of men who had been circumcised after the age of 35 was very small, so this should not be seen as strong evidence of an association. There was no statistically significant association between prostate cancer and circumcision for men circumcised at all other ages. No reason was collected for circumcision, so we can’t say if the association is with circumcision later in life or with whatever causes men to have circumcisions after that age. It is also highly likely that diet, lifestyle, socioeconomic status and healthcare behaviours may have played a role in skewing these results.”
- Sense About Science, April 8, 2014
Good news! Regular masturbation as a young man is more preventive of prostate cancer than circumcision!: New Scientist, reporting on this study:
BJU International, Volume 92, Issue 3, pages 211-216, August 2003
Sexual factors and prostate cancer
G.G. Giles, G. Severi, D.R. English, M.R.E. McCredie, R. Borland, P. Boyle, J.L. Hopper
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.
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.
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.
See also: "Marked in your Flesh" by Leonard Glick, pp. 190-193.
Arch circumcionists Brian Morris and Jake Waskett have joined forces to produce a masterpiece of special pleading and fallacious thinking, in a low-impact medical journal.
Asian Journal of Andrology advance online publication 28 May 2012
Circumcision reduces prostate cancer risk
Brian J Morris and Jake H Waskett
There is a strong negative correlation between prostate cancer and circumcision rate across 181 countries (P<0.0001).
[This "finding" is laughable. The circumcision figures are from an unpublished article by Waskett on his own site, circs.org. It gives the figure for Canada, for example, as "43.6%" (apparently the figure for Ontario in 1986-7; it had fallen to 18.6% there by 2002-3 - a trend which, were it to continue, would see an end to circumcision in Ontario next year or the year after.)
Their scattergram shows a cluster of low-cancer, high circumcision countries, presumably Muslim, and countries with a wide variety of other circumcision and cancer rates that prove nothing - especially when the correlation is across countries, with no indication whether the men with prostate cancer are actually circumcised. Another factor they fail to consider is life-expectancy, since prostate cancer is a disease of old men. ] Adding to the large protective effect of circumcision seen in small studies over the past six decades, a recent large study in Seattle has shown a smaller protective effect. [This is the Wright study, considered above.] If verified by other large studies elsewhere, the finding would add to the wide array of benefits conferred by this safe, simple procedure that is best performed in infancy.