Didn't realise this was already posted.
An interesting article from Yahoo.
Wednesday July 16, 07:44 PM
Masturbation could prevent cancer
Who cares if you go blind? An Australian study has found that frequent masturbation may protect men against prostate cancer in later life.
A team led by Professor Graham Giles, head of cancer epidemiology at the Cancer Council Victoria, questioned more than 2,000 men about their past sexual habits as part of a wider prostate cancer study.
The men, half of whom had prostate cancer, were aged between 40 and 69 and recruited from Sydney, Melbourne and Perth between 1994-98.
The study indicated that men who ejaculated more than five times a week were a third less likely to develop prostate cancer.
"What we found was men who ejaculated most in their twenties, thirties and forties had about a third less prostate cancer risk than men in the lowest category of ejaculation," Professor Giles told AAP.
"The men who were the high performers in terms of ejaculating had a third less prostate cancer risk than men who were in the lowest category of ejaculation."
He said one explanation for the apparent beneficial effects of self-pleasuring was that frequent ejaculation prevented semen from building up in the ducts, where it could potentially become carcinogenic.
"For seminal fluid to be made it has to be concentrated about 600 times," Prof Giles said.
"So semen is a very potent and strong brew of lots of chemicals which, because of their biological reactivity, could be carcinogenic if left to lie around."
The research is set to appear in the British Journal of Urology this weekend.