Risk factors for breast cancer in men

The exact cause of breast cancer is unknown. But certain things can increase the chance of developing it. These are called risk factors.

What are risk factors?

The exact cause of breast cancer is unknown. But certain things can increase the chance of developing it. These are called risk factors. Because breast cancer in men is rare, most men who have these risk factors will never develop breast cancer.

If you are worried about breast cancer and would like to talk to someone, we're here. You can:

Age

The risk of breast cancer in men increases with age. It is most common in men over 60. Breast cancer in young men is very rare.

Klinefelter syndrome

This is a rare syndrome that only affects men. Normally, men have 1 X chromosome and 1 Y chromosome (XY). Women have 2 X chromosomes (XX). Men with Klinefelter syndrome have 1 Y chromosome and 2 or more X chromosomes (XXY or XXXY).

Symptoms of Klinefelter syndrome include:

  • being taller than average
  • having increased breast tissue (gynaecomastia)
  • having lower levels of testosterone
  • having smaller testicles
  • not being able to make someone pregnant (infertility).

Men with Klinefelter syndrome have a higher risk of breast cancer. For most men, the lifetime risk of developing breast cancer is less than 1 in 1,000 (0.1%). For men with Klinefelter syndrome, the risk is closer to 1 in 25 (4%).

Family history of breast cancer

If you have close relatives with breast cancer, you may have an increased risk of developing breast cancer. About 1 in 5 men with breast cancer (20%) have a close relative who has had breast cancer. Close relatives are sometimes called your first-degree relatives. They are your parents, children, sisters and brothers. Grandparents are your second-degree relatives. But they may also be considered by doctors asking about your family history of breast cancer.

The increased risk may be caused by inherited gene changes. Our genes store the biological information we inherit from our parents. The genes most commonly linked to an increased risk of breast cancer in families are BRCA1 and BRCA2. Men in families with the BRCA2 gene are more likely to develop breast cancer than men in families with the BRCA1 gene. It is thought that the BRCA2 gene may cause up to 1 in 10 breast cancers in men (10%).

The chance of a gene change in a family is higher when:

  • a number of family members have been diagnosed with breast cancer or related cancers, such as ovarian cancer.
  • the family members are closely related
  • the family members were diagnosed at a younger age
  • a man in your family has been diagnosed with breast cancer.

If you are worried about breast cancer in your family, talk to your GP or a breast specialist. They can refer you to a family history clinic or a genetics clinic.

Men with breast cancer may be offered genetic testing, even if they do not have a family history of breast cancer.

Radiation

Being exposed to radiation may increase your risk of breast cancer. Radiotherapy to the chest before the age of 30 increases the risk of breast cancer. You may have radiotherapy to the chest to treat Hodgkin lymphoma. In this situation, you will usually be offered breast screening.

High oestrogen levels

Men may be at risk of developing breast cancer if they have higher levels of oestrogen than normal. Increased levels of oestrogen can affect the growth of breast cancer cells.

The liver helps to balance hormones in the body. Liver damage may cause increased levels of oestrogen. This may be long-term (chronic) damage, such as liver cirrhosis. It can be caused by drinking a lot of alcohol over a long period of time.

Being very overweight can also affect oestrogen levels.

Testicular effects

Conditions that affect or damage the testicles may also increase the risk of breast cancer. These include having:

  • undescended testicles
  • surgery to remove 1 or both testicles
  • mumps as an adult.

About our information

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Dr Rebecca Roylance, Consultant Medical Oncologist and Professor Mike Dixon, Professor of Surgery and Consultant Breast Surgeon.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

  • use plain English
  • explain medical words
  • use short sentences
  • use illustrations to explain text
  • structure the information clearly
  • make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.

Date reviewed

Reviewed: 01 October 2023
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Next review: 01 October 2026
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.