Sexual partners and cancer risk

New research links a history of 10 or more lifetime sexual partners to a heightened risk of being diagnosed with cancer.

In women, there is also a statistically significant positive association between the number of sexual partners and the risk of limiting long-standing illness, according to a paper in the journal BMJ Sexual & Reproductive Health.

A team of researchers from Austria, the UK, Canada, Turkey and Italy drew on information gathered for the English Longitudinal Study of Ageing (ELSA), a tracking study of people aged 50 and over.

It was an observational study and as such can’t establish cause. Nevertheless, they suggest the findings support 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 speculate that: “…the heightened risk of cancer might be driven by those types known to be associated with [sexually transmitted infections]”. 

In 2012-13, ELSA participants were asked to report on how many sexual partners they had had, their general health, and any long-standing condition or infirmity that impinged on routine activity. 

Other relevant information obtained included age, ethnicity, marital status, household income other than a pension, lifestyle (smoking, drinking, physical activity), and presence of depressive symptoms. 

Complete data were provided by 5722 of the 7079 people who responded to this question: 2537 men and 3185 women. Their average age was 64, and almost three out of four were married. 

Of the men, around 29% reported 0-1 sexual partners to date, 29% 2-4, 20% 5-9, and 22% 10 or more. The equivalent figures for women were 41%, 35%, 16% and 8%.

For both sexes, a higher number of sexual partners was associated with younger age, single status, and being in the highest or lowest brackets of household wealth. 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.

When all the data were analysed, a statistically significant association emerged between the number of lifetime sexual partners and risk of a cancer diagnosis among both sexes.

Compared with women who reported 0-1 sexual partners, those who said they had had 10 or more, were 91% more likely to have been diagnosed with cancer.

Among the men, those who reported 2-4 lifetime sexual partners were 57% more likely to have been diagnosed with cancer than were those who reported 0-1. And those who reported 10 or more, were 69% more likely to have been diagnosed with the disease.

While the number of sexual partners was not associated with reported long-standing conditions among the men, it was among the women. Women who reported 5-9 or 10+ lifetime sexual partners were 64% more likely to have a limiting chronic condition than those who said they had had 0-1.

An explanation for the gender difference remains “elusive,” the researchers write, especially given that men tend to have more lifetime sexual partners, and women are more likely to see a doctor when they feel ill – potentially limiting the associated consequences for their long-term health.