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Men who have sex with more than 20 women during the course of their
lifetimes are less likely to be diagnosed with prostate cancer, new
research shows.
But for homosexuals who have had sex with at least 20 men and virgins,
the risk of being diagnosed is doubled, the researchers from the
University of Montreal have found.
Compared with men who have had just one sexual partner, men who have
slept with 20 or more women have a 28 per cent lower risk of being
diagnosed, and are 19 per cent less likely to develop the most
aggressive form of prostate cancer.
However, the researchers found that homosexual men who have had at
least 20 sexual partners, were twice as likely to to develop prostate
cancer compared with those in monogamous relationships.
Homosexual men were also five times more likely to develop a less
serious form of the disease than those with only one male partner.
The "highly speculative" hypothesis to explain this increased risk for
homosexual men is that there is a heightened risk of picking up a
sexually transmitted disease and "physical trauma" to the prostate
from anal intercourse.
Between 2005 and 2009, 3208 men participated in the Prostate Cancer &
Environment Study and were asked to give information about their
lifestyles and sexual experiences.
In this time frame, 1590 men who participated in the study were
diagnosed with prostate cancer..
The research, published in the journalCancer Epidemiology, is the
first of its kind to make a link between the number of sexual partners
and the risk of developing cancer.
Lead researcher Marie-Elise Parent said that, despite the results, she
did not see a need for public health authorities to encourage men to
have sex with as many women as possible.
"It is possible that having many female sexual partners results in a
higher frequency of ejaculations, whose protective effect against
prostate cancer has been previously observed in cohort studies," Dr
Parent said
The research found that men who had never had sexual intercourse, were
twice as likely to be diagnosed with prostate cancer.
Prior studies have indicated sexual intercourse might help reduce the
risk of prostate cancer because it lowers the concentration of
carcinogenic crystal-like substances in the fluid of the prostate.
"We were fortunate to have participants from Montreal who were
comfortable talking about their sexuality, no matter what sexual
experiences they have had, and this openness would probably not have
been the same 20 or 30 years ago," Dr Parent said.
" Indeed, thanks to them, we now know that the number and type of
partners must be taken into account to better understand the causes
of prostate cancer."
Credit: Tom Decent
