High oestrogen levels increase breast cancer risk in men

A new report published by Cancer Research UK, in collaboration with a range of international partners, has shown that men with naturally high levels of the female hormone oestrogen may have a greater risk of developing breast cancer.


This is the first time a link between oestrogen levels in the blood and male breast cancer has been identified, despite its connection to breast, womb and ovarian cancers in women. According to the findings, men with the highest levels of oestrogen were two and a half times more likely to develop breast cancer than men with the lowest levels of the hormone.

The research, which took place at the National Cancer Institute in the US, was part of an international collaboration between Cancer Research UK, the National Cancer Institute and others. The study looked at a large international pool of men with breast cancer, comparing oestrogen levels in 101 men who went on to develop the cancer with 217 healthy men.

Study author Professor Tim Key, Cancer Research UK’s hormone and nutrition expert at the University of Oxford, said: “We’ve shown for the first time that just like some forms of the cancer in women, oestrogen has a big role to play in male breast cancer. So now the challenge is to find out exactly what this hormone is doing to trigger this rare form of the disease in men, and why some men have higher levels of oestrogen in their blood.”

Male breast cancer is very rare with one man in every 100,000 diagnosed with breast cancer each year in the UK. Around 350 male cases are diagnosed each year in the UK compared with nearly 50,000 cases of breast cancer in women. The symptoms, diagnosis and treatment of male breast cancer are very similar to breast cancer in women. The main risk of developing the disease in men is age, and almost eight in 10 cases are diagnosed in those aged 60 and older.

Dr Julie Sharp, head of health information at Cancer Research UK, said: “Breast cancer in men isn’t discussed very often, so a diagnosis can be a big shock for the small group of men who develop the disease. Some of the oestrogen variation in men will simply be natural, but for others there may be a link to being overweight. Fat cells in the body are thought to drive up the body’s level of this hormone in men and women, so this is another good reason to try and keep a healthy weight. This early research is crucial in understanding why these men get breast cancer – so that one day we can treat it more effectively.”

Gordon Wishart, Professor of Cancer Surgery and Medical Director of Check4Cancer, commented: “The link between oestrogen and breast cancer risk in men could prove a significant breakthrough. Breast cancer in women has a high profile, and in general women are very aware of the importance of self-checking and regular examinations. By contrast, awareness among men is extremely low, and those at risk from the disease are unlikely to know the warning signs or to be checking for them. That can mean a late diagnosis, with a poor probability of successful treatment. However, the proven connection with elevated oestrogen levels may help us to narrow the field by identifying the small group of men who are most at risk, educating them appropriately and, ultimately, detecting cancers at an earlier stage.”