The study, from Nottingham University, gave 800 men a questionnaire asking how often they had sex or masturbated. Researchers found that men who were more sexually active when they were younger ran a greater risk of developing prostate cancer.
This risk is probably linked to higher levels of sex hormones. The team, led by Polyxeni Dimitropoulou, recruited 400 men who had prostate cancer and compared them to 409 men who did not have the disease.
As well as questions about how often they had been sexually active from puberty onwards, they were asked how many sexual partners they had had and whether they had been diagnosed with any sexual infections.
Roughly the same proportion of both groups, 59%, said they had engaged in sexual activity 12 times a month or more in their 20s, falling to 48% in their 30s, 28% in their 40s and 13% in their 50s.
Almost two-fifths of the prostate cancer group had had six female partners or more, compared with less than a third of the non-cancer group.
There was also a difference among the men who masturbated or had sex the most often, with 40% of men in the cancer group being sexually active 20 times a month or more in their 20s, compared with 32% in the non-cancer group.
The gap between the two groups narrowed as the men aged, suggesting that the difference was strongest at a younger age.
