What is the correlation, if any, between the frequency of sexual
activity and the incidence of prostate cancer?

Hi curiousg,

Sexual frequency does not appear to be a significant risk factor for
developing prostate cancer.

The National Cancer Institute Center reports the following main risk
factors: age (over 55), family history of prostate cancer
(particularly father or brother), race (more common in African
American men, less common in Asian and American Indian men) and
dietary factors (a diet high in fruits and vegetables may decrease the
risk).

National Cancer Institute: Prostate Cancer
http://www.cancer.gov/cancer_information/cancer_type/prostate

From the above page you can click on the link 'Prostate Cancer
Prevention: Health Professionals' to see a summary of current
scientific evidence (with references) relating to risk factors, and
opportunities for prevention.

The Men's Health Institute has a page that specifically discusses the
issue of sexual frequency and risk of prostate cancer, with the same
conclusion:

https://www.sexandhealth.com/sh/mem_only/archives/Prostate/p2_10_98.html

It's true that prostate cancer never occurs in men who where castrated
before puberty, however this is related to androgen levels rather than
sexual frequency.


Additional resources:

A comprehensive page with links to a wide range of articles about
prostate cancer:

MEDLINEplus
http://www.nlm.nih.gov/medlineplus/prostatecancer.html


Google search strategy:

"prostate cancer" "sexual frequency"
://www.google.com/search?q=%22prostate+cancer%22+%22sexual+frequency%22

"prostate cancer" "risk factors"
://www.google.com/search?q=%22prostate+cancer%22+%22risk+factors%22


Regards,
eiffel-ga

The answer was good, althought most of the links given were too
general.
The one link answering the question is 4 years old. On the other hand,
the first comment to my question quotes a study made this year,
indicating
a POSSIBLE (though unlikely) link between higher frequency of sexual
activity and higher risk of prostate cancer.
Anyway, it was a good and prompt answer. Thanks a lot!

The results of a meta-analysis were published in January this year
(Meta-analysis of measures of sexual activity and prostate cancer.  by
Dennis LK, Dawson DV. of the Department of Epidemiology, College of
Public Health, University of Iowa, Iowa City, IA 52242, USA, in
Epidemiology, vol 13 pp 72-79).  A meta-analysis looks at data from a
number of separately published studies by different groups.  The
authors found an increased risk of prostate cancer in men with
sexually-acquired diseases (risk factor 1.4), especially syphilis
(risk factor 2.3), and in men with multiple partners (risk factor 1.2
for 20 partners).  The risk factor for sexual activity three times a
week was also increased to 1.2.  However, this a less clear finding. 
The authors suggest that infection can be one mechanism which
stimulates the development of prostate cancer.  They do not have an
explanation for how development of the disease could be linked to
frequency of sexual activity.
You can find a summary of the article on the web site of the journal
Epidemiology: http://www.epidem.com/article.asp?ISSN=1044-3983&VOL=13&ISS=1&PAGE=72

tehuti:

EXCELLENT ANSWER!  Finally someone who gives answers using
peer-reviewed medical journals.  Keep up the great work!

I found some more news related to this question:

http://www.blackwell-synergy.com/links/doi/10.1046/j.1464-410X.2003.04319.x/pdf

Or see

Sexual factors and prostate cancer
G.G. Giles ; G. Severi ; D.R. English ; M.R.E. McCredie ; R. Borland ;
P. Boyle ; J.L. Hopper, British Journal of Urology, vol. 92.3, p. 211,
August 2003.

at this site:

http://www.bjui.org/92/3/bju_v92_i3_toc.asp

It seems higher frequency of sexual activity actually decreases the
risk of prostate cancer. Highest risk reduction seems to come from 
frequent ejaculations (>5 times per week) due to masturbation, during
early adulthood (ages 20 to 30).