What are the risk factors for breast cancer?

What causes breast cancer in men?

It is not possible to say exactly what causes breast cancer in men. However, research has shown that there are some things that increase a man’s chance of developing breast cancer. These are called ‘risk factors’. There are different types of risk factors, some of which can be modified and some which cannot.

It should be noted that having one or more risk factors does not mean a person will develop breast cancer. Many people have at least one risk factor but will never develop breast cancer, while others with breast cancer may have had no known risk factors. Even if a person with breast cancer has a risk factor, it is usually hard to know how much that risk factor contributed to the development of their disease.

The most common risk factors are:

Less common factors that may increase risk include:

Some studies suggest there is a link between the risk of male breast cancer and the following:

Getting older

The incidence of breast cancer in men increases with age.  However men of all ages can be affected.  Breast cancer in men occurs more commonly in those aged 50 years and older.

Family history

Having a family history of female or male breast cancer on either side of the family can increase your risk of developing breast cancer. You may have inherited a fault in a gene which could eventually lead to the development of breast cancer.

Family history becomes more important in increasing your risk of breast cancer:

  • the more blood relatives you have on one side of the family who have had breast cancer or ovarian cancer; the family history may be on your mothers’ side or fathers’ side of the family
  • the younger these relatives were when they were first diagnosed with breast cancer
  • the more closely related these relatives are to you.

Most men who develop breast cancer do not have a strong family history of the disease. If you are concerned about your risk based on family history see your GP.

For men diagnosed with breast cancer, referral to a family cancer clinic for genetic assessment should be considered, particularly if there is Jewish ancestry, a family history of breast or ovarian cancer or if the family history is unknown.

High oestrogen levels

Men with higher than normal levels of the female hormone oestrogen may have a greater risk of developing breast cancer. High oestrogen levels are associated with:

  • obesity
  • long-term liver conditions, such as cirrhosis
  • some genetic conditions.

Klinefelter’s syndrome

Klinefelter’s syndrome is a rare condition affecting 1 in 500 to 1 in 1000 men. Men with Klinefelter’s syndrome have two X (female) chromosomes and one Y (male) chromosome (XXY) instead of a single X and single Y chromosome (XY). Symptoms of Klinefelter’s syndrome include longer legs, a higher voice, a thinner than average beard, smaller than normal testicles, and the inability to produce sperm (infertility). Men with this syndrome also have lower levels of male hormones and higher levels of female hormones. Men with Klinefelter’s syndrome have a greater risk of developing breast cancer.

Testicular disorders

Testicular disorders, including testicular infection (orchitis), testicular injury or undescended testis, may be associated with increased breast cancer risk in men.

Radiation exposure

Men who have been exposed to radiotherapy repeatedly over a long period of time, usually for treatment of a cancer inside the chest such as Hodgkin or non-Hodgkin lymphoma may have an increased risk of developing breast cancer.