Breast cancer is often thought of as a condition that only affects women, but men can also develop it.
It's much less common in men than women, with only around 1 new case of breast cancer diagnosed for every 100,000 men (about 350 to 400 cases) in the UK each year.
The cancer develops in the small amount of breast tissue men have behind their nipples. The most common symptom is a hard, painless lump in one of the breasts.
However, the vast majority of breast lumps are caused by a condition called gynaecomastia. This is a common non-cancerous condition where male breast tissue becomes enlarged.
Breast cancer in men can also cause nipple problems, such as the nipple turning in on itself (retraction) or nipple discharge.
Read more about the symptoms of male breast cancer.
You should always talk to your GP if you notice a lump in your breast or you have problems affecting your nipples, such as discharge.
While these symptoms are unlikely to be caused by breast cancer, they should be investigated further.
The cause of male breast cancer is unclear, but factors known to increase your chances of developing the condition include:
Read more about causes of breast cancer in men.
In most cases, surgery is used to remove the cancer, along with a section of the breast. This may be followed by a long-term course of hormone-blocking therapy using medication, usually a drug called tamoxifen.
Tamoxifen helps block the effects of hormones known to stimulate the growth of cancerous cells in breast tissue. It should help prevent the cancer returning.
Read more about treating breast cancer in men.
The outlook for breast cancer is not as good in men as in women. This is because there's reduced awareness of the condition and it may take longer to diagnose.
The survival rates for breast cancer in men largely depend on how far the cancer has spread before it's diagnosed.
Breast cancer diagnosed at an early stage can often be treated successfully, but effective treatment is more difficult if the cancer has spread beyond the breast tissue.
Unfortunately, many cases are diagnosed after the cancer has already started to spread.
Read more about diagnosing breast cancer in men.
The most effective way of reducing your risk of developing breast cancer, as well as other serious health conditions, is to:
Read more about preventing cancer.