Men with severely reduced fertility are at greater risk of developing other health conditions later in life. A research team from Lund University in Sweden has now shown that these men are also more likely to develop colorectal cancer and thyroid cancer.
The link between male infertility and an increased risk of disease is a relatively new area of research in reproductive health. Previous studies have shown that there is a clear link between lower male fertility and the risk of developing diabetes, cardiovascular disease and metabolic disorders, cancer of the reproductive organs, and a shorter life expectancy. Men who have no sperm in their semen are among those most at risk from several serious illnesses, whilst men with good sperm quality tend to live longer on average. As a result, researchers are increasingly discussing whether male fertility can serve as an early warning sign – a biological marker – for general health.
“Reproductive capacity is linked to an individual’s genetic makeup. One theory is that if something goes wrong at the genetic level – which can manifest as reduced sperm quality – other systems in the body may also be affected, increasing the risk of disease,” says Angel Elenkov, docent and researcher at Lund University and consultant physician at the Centre for Reproductive Medicine, Region Skåne.
Epigenetic mechanisms – that is, how genes are regulated and influenced by factors such as the environment and lifestyle without any changes to the genetic material – as well as lifestyle factors such as obesity, smoking, alcohol consumption and physical inactivity are linked to poorer sperm quality.
“It has previously been found that men with severely reduced fertility are at increased risk of developing testicular and prostate cancer. That is why we wanted to investigate whether there is also a link to other forms of cancer,” says Michael Kitlinski, a medical student and research project participant at Lund University.
Using registry data, the researchers were able to analyse data from over 1.1 million Swedish men who had their first child between 1994 and 2014. Of these, 14,540 became fathers with the help of ICSI* – an assisted reproduction technique used to treat severe male infertility. All the men were then cross-referenced against the national cancer registry, which revealed a significantly increased risk of colorectal cancer and thyroid cancer among men who had become fathers through ICSI.
“They were found to have almost twice the risk of developing colorectal cancer and three times the risk of thyroid cancer compared with men who become fathers naturally,” continues Michael Kitlinski.
However, although the relative risk is higher among people who have undergone ICSI treatment, it remains low at population level, and cancer is rare in this age group. The researchers also emphasise that it is not the fertility treatment itself that causes cancer.
“Most men who undergo fertility testing are between 30 and 35 years old. The aim is to help them become fathers, and there is no subsequent follow-up on their health. These findings are important from a public health perspective given that cancers of the colon and rectum, as well as thyroid cancer, are on the rise among younger people. These cancers could be prevented through early screening.” says Angel Elenkov.
The researchers’ next step is therefore to work in collaboration with other clinics in Scandinavia to further refine the risk groups by identifying biomarkers, genetic mutations, epigenetic factors and environmental factors. The ongoing Swedish-Danish initiative RUBIC (ReproUnion Biobank and Infertility Cohort), which aims to create the world’s largest research database and biobank focusing on couples affected by involuntary childlessness, will be a key resource in addressing these issues. It is hoped that this will provide a better understanding of which groups would benefit from preventive health checks.
Epidemiological research // Peer-reviewed publication // Registry-based study // Observational study // Longitudinal // Cohort study
Number of groups in the study: grouped based on the method by which fatherhood was achieved (via ICSI 14 540, via standard IVF 20 142, and 1 103 147 through natural conception). Number of patients in the study: 1 137 829
ICSI* (intracytoplasmic sperm injection) is a form of IVF in which a single sperm is injected directly into the egg. This method is used to treat severe male infertility, such as very low sperm count or reduced sperm motility.
IVF (in vitro fertilisation) is a method of assisted reproduction in which eggs are retrieved from the woman’s ovaries and combined with sperm in a laboratory. The sperm must find their way into the egg and fertilise it themselves.
European Journal of Epidemiology
Observational study
People
Risk of non-reproductive cancer in men from couples conceiving through assisted reproduction: a Swedish nation-based register study
21-Feb-2026