More promiscuous people are more likely to get cancer in old age, according to a study.
Researchers found that having 10 or more sexual partners over a lifetime almost doubled the risk of a woman developing cancer, and raised it by two thirds for men.
A link between sexually-transmitted infections and cancers – HPV, for example, is known to raise the risk of diseases in the cervix and penis – could be to blame.
And people who had sex with more partners also tended to drink more alcohol and smoke more cigarettes, the scientists said – but they also did more exercise.
The finding was no reason to avoid having sex, they added, and said that intercourse brings a variety of physical and mental health benefits which outweighed the longer-term risk.
Researchers from Anglia Ruskin University, Cambridge, collected data from nearly 6,000 men and women over the age of 50.
Among men, those who reported more than 10 lovers in their lives had a 69 per cent higher chance of getting cancer, compared with those who had bedded only one or none.
Women who reported 10 or more sexual partners were found to be 91 per cent more likely to have been diagnosed with cancer.
Only 486 men (19 per cent) and 239 women (7.5 per cent) admitted to having had sex with 10 or more people.
Dr Lee Smith, an Anglia Ruskin University expert and the author of the study, told MailOnline: ‘We expected there to be an association between number of sexual partners and cancer risk as previous research has shown that specific STIs may lead to several cancers.
‘Indeed, a higher number of sexual partners means greater potential exposure to STIs. It is interesting that the risk is higher in women when compared to men.
‘This may be because the link between certain STIs and cancer is stronger in women, such as HPV (Human papillomavirus) and cervical cancer compared to HPV and penile cancer.’
People in the study, which was published in the journal BMJ Sexual and Reproductive Health, had an average age of 64 and most were married.
The most common category for both sexes was one or no sexual partners – 785 out of 2,537 men and 1,285 out of 3,185 women.
In both sexes, people with a more colourful sexual history also tended to be younger, single and in either the richest or the poorest communities.
And those who reported a higher tally of sexual partners were also more likely to smoke, drink frequently, and do more vigorous physical activity on a weekly basis, the study found.
When all the data was analysed, a significant association emerged between the number of lifetime sexual partners and risk of a cancer diagnosis among both sexes.
Participants were also asked to rate their own health and report any long standing condition or infirmity which impinged on routine activity in any way.
Researchers claim the results provide some evidence that the number of lifetime sexual partners is associated with adverse health outcomes in a sample of older adults in England.
However, Dr Smith did not want to discourage people from having sex.
He said: ‘Sexual activity has multiple physical and mental health benefits especially in older age and we would not want to discourage sexual activity among older adults.
‘People who had risky sexual encounters should contact their health care providers to get checked for potential sexually transmitted infections and should discuss openly about how to minimise this risk with their health care providers. Using appropriate protection will reduce the risk of related cancers going forward.’
Researchers noted that their study could not establish cause but said the findings chime with those of previous studies, implicating sexually transmitted infections in the development of several types of cancer and hepatitis.
They didn’t obtain information on the specific types of cancer participants reported, but speculated: ‘…the heightened risk of cancer might be driven by those types known to be associated with [sexually transmitted infections].’
And they suggested that inquiring about the number of sexual partners might complement existing cancer screening programmes by helping to identify those at risk.
That is, if further research can establish a causal association between the number of sexual partners and subsequent ill health.
But an explanation for the gender difference in long term condition risk remains ‘elusive,’ they wrote, especially given that men tend to have more lifetime sexual partners than women, while women are more likely than men to see a doctor when they feel ill, so potentially limiting the associated consequences for their long term health.