Higher oestrogen levels in men ‘can increase breast cancer risk’

A new study has established a link between higher oestrogen levels in the blood and male breast cancer for the first time.

Researchers at the National Cancer Institute in the US – part of an international collaboration between Cancer Research UK, the National Cancer Institute and others – made this discovery after comparing oestrogen levels in 101 men who went on to develop breast cancer with 217 healthy men.

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, it was shown.

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.

Study author Professor Tim Key, Cancer Research UK's hormone and nutrition expert at the University of Oxford, said: "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."

Around 350 male cases of breast cancer are diagnosed each year in the UK, compared with nearly 50,000 cases in women.