Men too can get breast cancer and those with naturally high levels of the female hormone estrogen may be at a greater risk, shows a new study.
Men with the highest levels of estrogen were two-and-a-half times more likely to develop breast cancer than men with the lowest levels of the hormone, the researchers found.
"We have shown for the first time that just like some forms of the cancer in women, estrogen has a big role to play in male breast cancer," said study author professor Tim Key from Cancer Research UK.
"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 estrogen in their blood. Our discovery is a crucial step forward in understanding the factors behind male breast cancer," he noted.
The research at the National Cancer Institute in the United States was part of an international collaboration between Cancer Research UK, the National Cancer Institute and others.
The researchers compared estrogen levels in 101 men who went on to develop breast cancer with 217 healthy men. Although rare, 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.
"This early research is crucial in understanding why these men get breast cancer -- so that one day we can treat it more effectively," Julie Sharp, head of health information at Cancer Research UK, noted.
The findings were detailed in the Journal of Clinical Oncology