The Cancer Council Victoria has announced the results of research undertaken into the relationship between prostate cancer and ejaculation in men aged under 70.
A research team led by Professor Graham Giles, Director of the Cancer Council's Cancer Epidemiology Centre, has found that there is evidence that the more frequently men ejaculate between the ages of 20 and 50, the less likely they are to develop prostate cancer.
The researched showed that the protective effect of ejaculation is greatest when men in their twenties ejaculated on average seven or more times a week. This group were one-third less likely to develop aggressive prostate cancer when compared with men who ejaculated less than three times a week at this age.
Professor Giles said, "We looked at a number of different aspects of sexual activity including the number of sexual partners, the frequency of ejaculation, as well as the number of times men ejaculated at different ages, from their twenties through to their fifties.
"The study looked at ejaculation in the context of intercourse with another person, masturbation, nocturnal emissions etc.
"This is a different approach from previous studies which have mostly looked at links between sexual intercourse and prostate cancer.
"Our research indicates that there is no association between prostate cancer and the number of sexual partners, which argues against infection as a cause of prostate cancer in the Australian population."
"We also found no association between maximum number of ejaculations in a 24 hour period and prostate cancer. Therefore, it is not men's ability to ejaculate that seems to be important.
"While it is generally accepted that prostate cancer is a hormone dependent cancer, apart from age and family history, its causes are poorly understood."
"For this reason, our explanations are fairly speculative - one possible reason for the protective effects of ejaculation may be that frequent ejaculation prevents carcinogens building up in the prostatic ducts."
"If the ducts are flushed out, there may be less build up and damage to the cells that line them."
"However, this is only one study and our findings require further corroboration in other studies.
The research was conducted with men who were under the age of 70 when they were diagnosed with prostate cancer, and with a group of similarly aged healthy men. There were 1079 men with prostate cancer and 1259 healthy men in the study. The men were from Melbourne, Sydney and Perth.
The men filled in a confidential questionnaire which sought details of their sexual activity at various times in their life. The results of the survey were treated confidentially.
Professor Giles said, "We believe that the men who participated in the study were likely to have been honest about their sexual activity because of the way the research was conducted, particularly using a questionnaire that men filled out themselves, and respecting their privacy."
"The fact that we did not find any association with the number of sexual partners argues against the possibility of the finding in regard to ejaculation being due to bias, as if this was the case we would have expected both associations to be positive."
The project involved researchers from The Cancer Council Victoria, The University of Western Australia, The European Institute of Oncology and the Dunedin Medical School, University of Otago, New Zealand.
The research was funded by the National Health and Medical Research Council and supported by funding from Tattersall's and The Whitten Foundation, as well as The Cancer Council Victoria.
The research is being published in the British Journal of Urology International vol 92, p 211.