Sydney: The more sexual partners a man has may double his risk of developing prostate cancer, a study has claimed.
The study found that men who had more than seven sexual partners in their lifetime were twice as likely to have prostate cancer than those with fewer than three partners.
Men who are sexually active earlier may also be a risk, the researchers said.
"The more partners you had, the more orgasms you had, the younger you were when you first had sex, all pointed to an increased prostate cancer risk," Visalini Nair-Shalliker, doctoral student at Cancer Council New South Wales in Australia, was quoted as saying to smh.com.au.
It's believed this increased risk associated with sexual activity could be due to hormonal changes.
Sexual activity and metabolism were associated with antigen, a male sex hormone that is also strongly linked to the initiation of prostate cancer.
Other risk factors included having a father with a history of prostate cancer, a previous diagnosis of prostatitis or benign prostatic hyperplasia.
In addition, the study found that being overweight or obese was also associated with increased risk of the disease, but to a lesser extent.
There was no association found between prostate cancer risk and circumcision, vasectomy or erectile function, the researchers observed.
It is important to identify risk factors so men could be given advice, and men aged over 50 who fell into those risk categories should speak to their doctors, especially if they had a family history of the disease, Nair-Shalliker said.
However, "we can't make any recommendations around sexual activity because it's multi-faceted. We're not saying 'increase or decrease your sexual activity' because the evidence is still grey about that," Nair-Shalliker noted, in the paper published in the journal in the International Journal of Cancer.