• Written by Jayne Lucke, Honorary Professor, The University of Queensland
Shutterstock

A study published today claims to have found a link between having had ten or more sexual partners and an increased risk of cancer. But it’s not as simple as that.

While having a sexually transmissible infection (STI) can increase the risk of certain types of cancer, using a person’s lifetime number of sexual partners as a marker of their likely sexual health history is one of several flaws in this research.

The evidence from this study isn’t strong enough to conclude that having had multiple sexual partners increases a person’s risk of cancer.

Misinterpreting these findings could lead to stigma around STIs and having multiple sexual partners.


Read more: Health Check: can sex affect your risk of getting cancer?


What the study did

The research, published in the journal BMJ Sexual & Reproductive Health, used data from 2,537 men and 3,185 women participating in the English Longitudinal Study of Ageing, a nationally representative study of adults aged 50+ in England.

The average age of participants was 64. Most were married or living with a partner, white, non-smokers, drank alcohol regularly, and were at least moderately active once a week or more.

Participants were asked to recall the number of people with whom they had ever had vaginal, oral or anal sex in their lifetime. The researchers grouped the responses into four categories shown in the table below.

The researchers then examined associations between lifetime number of sexual partners and self-reported health outcomes (self-rated health, limiting longstanding illness, cancer, heart disease and stroke).

The researchers controlled for a range of demographic factors (age, ethnicity, partnership status, and socioeconomic status) as well as health-related factors (smoking status, frequency of alcohol intake, physical activity, and depressive symptoms).

What the study found

Men with 2-4 partners and 10+ partners were more likely to have been diagnosed with cancer, compared to men with 0-1 partners. There was no difference between men with 0-1 partners and 5-9 partners.

Compared to women with 0-1 partners, women with 10+ partners were more likely to have been diagnosed with cancer.

Women with 5-9 partners and 10+ partners were also more likely to report a “limiting longstanding illness” than those with 0-1 partners.

The authors don’t specify what constitutes a limiting longstanding illness, but looking at the questions they asked participants, we can ascertain it’s a chronic condition that disrupts daily activities. It’s likely these ranged from mildly irritating to debilitating.


Read more: New Gardasil 9 vaccine boosts teens' protection from HPV and cervical cancer by 23%


There was no association between number of sexual partners and self-rated general health, heart disease or stroke for either men or women.

Notably, while statistically significant, the effect size of all these associations was modest.

Misunderstanding these results could create stigma around STIs, which can deter people from sexual health check ups. Shutterstock

What does number of sexual partners have to do with cancer risk?

There is a reason for investigating whether a person’s lifetime number of sexual partners has anything to do with their cancer risk. If you’ve had a lot of sexual partners, it’s more likely you’ve been exposed to an STI. Having an STI can increase your risk of several types of cancer.

For example, human papillomavirus (HPV) is responsible for 30% of all cancers caused by infectious agents (bacteria, viruses or parasites), contributing to cervical cancer, penile cancer, and cancers of the mouth, throat and anus.

Viral hepatitis can be transmitted through sex, and having chronic hepatitis B or C increases the risk of liver cancer.

Untreated HIV increases the risk of cancers such as lymphomas, sarcomas and cervical cancer.


Read more: Is Truvada (PrEP) the game-changer that will end new HIV transmissions in Australia?


How can we make sense of this?

The authors of the study acknowledge the numerous limitations of the analysis and recommend further work be done to confirm their findings. We must interpret their results with this in mind.

Their use of lifetime number of sexual partners as a proxy measure for STI history is a key problem. While there is an association between having a higher number of partners and an increased risk of STIs, many other factors may be important in determining a person’s risk of being infected with an STI.

These include whether they’ve practised safe sex, what type of infection they might have encountered, and whether they’ve been vaccinated against, or treated for, particular infections.

Further, the analysis was based on cross-sectional data – a snapshot that doesn’t account for changes over time. Participants were asked to recall information from the past, rather than having measurements taken directly at different time points. It’s not possible to establish causation from a cross-sectional analysis.

Even if the association is confirmed in prospective, longitudinal studies, the findings may not apply to other groups of people.

Recent advances in vaccine development (such as the wide availability of the HPV vaccine), better STI prevention (such as the use of pre- and post-exposure prophylaxis – PreP and PEP – for HIV) and more effective therapy (for example, direct-acting antiviral agents to treat hepatitis C) will reduce the impact of STIs on cancer risk for those who can access them.

We now have a vaccine to prevent HPV, which in turn reduces the risk of cervical and other cancers. Shutterstock

People with higher numbers of sexual partners were more likely to smoke and drink frequently (increasing the risk of cancer), but also to do more vigorous physical activity (decreasing the risk of cancer).

For women, a higher number of sexual partners was associated with white ethnicity; for men, with a greater number of depressive symptoms. Although the researchers controlled for these factors, these points highlight some inconsistencies in the pattern of results.

The researchers also couldn’t explain why a greater number of sexual partners was associated with a higher likelihood of a limiting chronic condition for women, but not for men.

Ultimately, this study raises more questions than it answers. We need further research before we can use these results to inform policy or improve practice.


Read more: Stigma and lack of awareness stop young people testing for sexually transmitted infections


The paper concludes by saying enquiring about lifetime sexual partners could be helpful when screening for cancer risk. This is a very long stretch based on the evidence presented.

This approach could also be harmful. It could invade privacy and increase stigma about having multiple sexual partners or having an STI.

We know experiencing stigma can discourage people from attending sexual health screenings and other services.

It would be better to put limited health resources towards improving prevention, screening and treatments for STIs.

Jayne Lucke receives funding from the Australian Research Council and the National Health and Medical Research Council. She has served as a Director of Family Planning Queensland and been Chief Investigator on an ARC Linkage Grant that received cash and in-kind support from Family Planning New South Wales and Bayer Australia.

Authors: Jayne Lucke, Honorary Professor, The University of Queensland

Read more https://theconversation.com/saying-sex-increases-cancer-risk-is-neither-totally-correct-nor-in-any-way-helpful-131747

Switch It Up: What’s the Relationship Between Lighting and Your Work Performance

It’s no secret that light has an immense impact on the way our bodies function on a daily basis. Light is closely linked to our circadian rhythms or our ‘built-in clocks’, and as such, it larg...

Lilly Miller - avatar Lilly Miller

How to Get Rid of Rats?

Do you suffer from scratching noise in the night or find strange signs such as gnawed pieces of wooden furniture or droppings in your house? Then, you have to prepare for an unpleasant fight with ro...

News Company - avatar News Company

VIDEO: Michelle Grattan on an extended travel ban, a royal commission, and zero emissions by 2050

Michelle Grattan talks with Assistant Professor Caroline Fisher about the week in politics, including the extension of the coronavirus travel ban, the royal commission into the bushfires, and labor&rs...

Michelle Grattan, Professorial Fellow, University of Canberra - avatar Michelle Grattan, Professorial Fellow, University of Canberra

I've seriously tried to believe capitalism and the planet can coexist, but I've lost faith

RAJAT GUPTA/EPAThis article is the first in a three-part series on radical ideas to solve the environmental crisis. As the Productivity Commission confirmed this week, Australia’s economy has ...

Samuel Alexander, Research fellow, Melbourne Sustainable Society Institute, University of Melbourne - avatar Samuel Alexander, Research fellow, Melbourne Sustainable Society Institute, University of Melbourne

What is hypnobirthing, the technique the Duchess of Cambridge used?

In a new parenting podcast, Catherine, the Duchess of Cambridge, said she used hypnobirthing techniques to help her get through severe morning sickness – a condition called hyperemesis gravidaru...

Mary Steen, Professor of Midwifery, University of South Australia - avatar Mary Steen, Professor of Midwifery, University of South Australia

Memories overboard! What the law says about claiming compensation for a holiday gone wrong

FRANCK ROBICHON/EPAWhen booking a luxury cruise, you generally expect relaxation and enjoyment, not forced quarantine and distress. Unfortunately, for the thousands of vacationers trapped on cruise s...

Mark Giancaspro, Lecturer in Law, University of Adelaide - avatar Mark Giancaspro, Lecturer in Law, University of Adelaide

Without more detail, it's premature to say voluntary assisted dying laws in Victoria are 'working well'

ShutterstockThe Voluntary Assisted Dying Review Board has this week published a report detailing the first six months of the legislation in action in Victoria. The report reveals 52 people legally e...

Courtney Hempton, Associate Research Fellow, Deakin University - avatar Courtney Hempton, Associate Research Fellow, Deakin University

I've always wondered: who would win in a fight between the Black Mamba and the Inland Taipan?

Wes Mountain/The Conversation, CC BY-NDThis is an article from I’ve Always Wondered, a series where readers send in questions they’d like an expert to answer. Send your question to always...

Timothy N. W. Jackson, Postdoctoral Research Fellow, Australian Venom Research Unit, University of Melbourne - avatar Timothy N. W. Jackson, Postdoctoral Research Fellow, Australian Venom Research Unit, University of Melbourne

Australia, we need to talk about who governs our city-states

Benny Marty/ShutterstockIn 1971, a Time magazine article, titled “Should New York City Be the 51st State?”, observed: States have not only short-changed and hamstrung their cities but a...

Benjamen Franklen Gussen, Lecturer in Law, Swinburne University of Technology - avatar Benjamen Franklen Gussen, Lecturer in Law, Swinburne University of Technology

Sick and Tired of Your Dead End Job? Try Teaching!

Tired of the same old grind at the office? Want an opportunity to impact lives both in your community and around the world? Do you love to travel and have new experiences? Teaching English is the perfect job for you! All you need is a willingness to ...

News Company - avatar News Company

The Impact of an Aging Population in Australia

There’s an issue on the horizon that Australia needs to prepare for. The portion of elderly citizens that make up the country’s overall population is increasing, and we might not have the infrastructure in place to support this. Australians h...

News Company - avatar News Company