In one of the largest studies into male breast cancer, scientists at The Institute of Cancer Research, London, studied 1,998 men newly diagnosed with the disease in England and Wales over a 12-year period.
Around 370 men are diagnosed with breast cancer each year in the UK.
Because male breast cancer is rare, research into the disease is usually limited to a small number of patients.
However, studying a larger group of men enabled the team to show a statistically significant association between infertility and risk of invasive breast cancer in men.
Participants were asked whether they had biological children, if they or their partners had ever experienced problems conceiving, or if they had visited a doctor or clinic for fertility concerns.
The team directly compared the fertility of the men with breast cancer to 1,597 men with no history of the disease.
They factored in other known risk factors for infertility and breast cancer that could affect the association, including alcohol consumption, smoking, family history of breast cancer and liver disease.
While the biological reason is unclear, researchers discovered that men diagnosed with breast cancer were more likely to report fertility issues.
Supporting this, they also found there were significantly more men with no children among those who had been diagnosed with breast cancer – both overall and after restricting the analysis to married men only.
This finding provides grounds for further work to understand potential links between testosterone production or oestrogen exposure for men developing the disease.
And it could be a step towards identifying the underlying causes of male breast cancer, which are largely unknown.
The findings, published in Breast Cancer Research, are part of the wider Male Breast Cancer Study launched by Breast Cancer Now in 2007 to pinpoint the genetic, environmental and lifestyle causes of breast cancer in men, to help identify those at risk and understand what can be done to lower their chances of developing the disease.
Study author Dr Michael Jones, Senior Staff Scientist in Genetics and Epidemiology at The Institute of Cancer Research, London, said:
“These are important findings linking infertility to breast cancer in men.
"Our study suggests that infertile men may be twice as likely as those without fertility issues to develop breast cancer.
"The reasons behind this association are unclear, and there is a need to investigate the fundamental role of male fertility hormones on the risk of breast cancer in men.
"We hope this could lead to insights into the underlying causes of male, and possibly even female, breast cancer.
“Breast cancer is often thought of as something that only affects women, but men can also be diagnosed with the disease.
"Compared with previous studies, our study of male breast cancer is large. It was carried out nationwide across England and Wales and was set in motion more than 15 years ago.
"Because of how rare male breast cancer is, it took us over 12 years to identify and interview the nearly 2,000 men with breast cancer who were part of this study.”
Dr Simon Vincent, Director of Research, Support and Influencing at Breast Cancer Now, said:
“Many people don’t realise that men can get breast cancer, because incidence is much lower in men than women.
"However, every year in the UK, around 370 men are diagnosed with breast cancer, and around 80 men die from it and it’s vital that we support anyone affected by breast cancer.
“Research has discovered different treatments directed at some features of breast cancer in women. However, breast cancer is not as well understood for men.
"This is why Breast Cancer Now funds the Male Breast Cancer Study which looks at what might cause the disease in men.
"Discovering a link between infertility and male breast cancer is a step towards us understanding male breast cancer and how we could find more ways to diagnose and treat men – and possibly women – with this devastating disease.
“Importantly, we hope the knowledge we have gained from this study reaches more men who might benefit from being aware of male breast cancer.
"Anyone seeking information and support can speak to Breast Cancer Now’s expert nurses by calling the charity's free Helpline on 0808 800 6000.”
Dave, 64, from Bristol was a police officer for 22 years before retiring to set up his own IT company. Dave was diagnosed with breast cancer in 2015. He said:
“I was on holiday in Florida, celebrating my birthday, when I found a lump on my chest in the shower.
"I wasn’t aware that men should check for breast cancer, but I know that if your body changes, you shouldn’t leave it. So I went to see my GP as soon as I got home and they referred me to see a specialist consultant.
"Despite being told it was probably just a fatty deposit, I had an ultrasound and biopsy. One week later I was diagnosed with breast cancer. The tumour was the size of a golf ball.
“Of course, when I was first diagnosed I was scared and it was tough to tell my children.
"I had a mastectomy, treatment and almost seven years later I'm in good health and still receiving a course of drugs that can reduce the rate of cancer returning.
“My mother died from ovarian cancer when she was 68, and I knew there was a link between ovarian and breast cancer. But generally, little is known about male breast cancer.
"People will say ‘I didn’t realise men could get that’ and to be honest, I didn’t think I would ever get it!
“It’s really interesting that if you’re affected by fertility issues, you could be more likely to be affected by breast cancer.
"I’m lucky that I haven’t been impacted by fertility problems. But it’s important scientists build on Breast Cancer Now’s research, as it could help to find out what causes some male breast cancers and one day even lead to developing new treatments.”
ENDS
For more information or to arrange an interview, please contact the Breast Cancer Now press office at press@breastcancernow.org or on 07436 107914.
Notes to Editors
For more information on breast cancer in men, signs and symptoms, go to: https://breastcancernow.org/breast-cancer-in-men
About Breast Cancer Now
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- Breast Cancer Now’s ambition is that, by 2050, everyone who develops breast cancer will live and be supported to live well.
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