Men who are sexually active in their twenties and thirties are more likely to develop prostate cancer later in life according to a new study.

The study, conducted on more than 800 men, shows men who frequently masturbate are at greater risk, according to the January issue of BJU International.

The study, led by the University of Nottingham, looked at the sexual practices of more than 431 men who had been diagnosed with prostate cancer before the age of 60, together with 409 controls.

Men who took part in the study were asked about all aspects of their sexual conduct, including how active they were, when they began engaging in intercourse, and how often they masturbate. The study participants were asked to fill in a questionnaire about their sexual habits in each decade of their life since their twenties.

Hormones appear to play a key role in prostate cancer and it is very common to treat men with therapy to reduce the hormones thought to stimulate the cancer cells, said lead author Dr Polyxeni Dimitropoulou, who is now at the University of Cambridge.

A man's sex drive is also regulated by his hormone levels, so this study examined the theory that having a high sex drive affects the risk of prostate cancer.

More men with prostate cancer fell into the highest frequency groups in each decade when it came to sexual activity than men in the control group, and 40 percent of men in the cancer group fell into the highest frequency category in their twenties (20 or more times a month) compared to 32 percent in the control group. Similar patterns were observed in the men's thirties and forties.

Men with prostate cancer were also more likely to masturbate frequently than men in the control group, with the greatest difference in the twenties (34% versus 24%) and thirties (41% versus 31%).

What makes our study stand out from previous research is that we focused on a younger age group than normal and included both intercourse and masturbation at various stages in the participants' lives says Dr Dimitropoulou.

Overall we found a significant association between prostate cancer and sexual activity in a man's twenties and between masturbation and prostate cancer in the twenties and thirties. However there was no significant association between sexual activity and prostate cancer in a man's forties.

A possible explanation for the protective effect that men in their fifties appear to receive from overall sexual activity, and particularly masturbation, is that the release of accumulated toxins during sexual activity reduces the risk of developing cancer in the prostate area. This theory has, however, not been firmly established and further research is necessary.