Overview

Prostate cancer is the most common cancer in men. If you have prostate cancer, you might be offered germline testing. This test tells us if you and your relatives have an increased risk of cancer because of a gene change (mutation) that is passed from parent to child (inherited).

Germline testing is done on cells that are not affected by cancer. This is usually done from a blood sample. 

Finding a germline gene mutation might affect your cancer risk, as well as the cancer risk for members of your family. If a gene mutation is found, we could also offer to test your relatives.

If you have a germline mutation, there is a 1 in 2 (50%) chance of passing on the mutation to each child you have, whatever the child’s sex. This does not mean your children have a 1 in 2 chance of getting cancer, or will definitely get cancer. But it does increase their lifetime risk of some cancers in the future.

Knowing that there's an increased risk means you and your family can take steps to manage your risk of developing cancer. You can make certain lifestyle changes to lower your risk, have regular screening and have preventative treatment. However, you might want to think carefully before making a decision.

Not everyone who is offered germline testing will choose to have it. It is your choice. You might choose to reconsider genetic testing in the future.

Who is offered germline testing

You might be offered germline testing if:

• a genetic change (somatic mutation) was identified through tumour testing on a sample of your cancer. Mutations found in the tumour are usually non-inherited but more rarely they are inherited (germline). To confirm if this is the case for you, a germline test is usually done
• you have a known family history of cancers. Genetic testing can indicate if there is an inherited reason for your cancer
• you were diagnosed using national criteria

Your doctor will discuss the reasons you're being offered genetic testing.

Inherited prostate cancer

1 in 6 men will have prostate cancer in their lifetime. Most prostate cancers happen by chance.

Getting older is the main thing that increases your risk of cancer. The older we get, the more likely we are to develop cancer, because our bodies become less effective at protecting us. Ethnicity can also increase your risk. Prostate cancer is more common in Black and African men than White men. It is least common in Asian men.

However, 9 in 100 prostate cancers are caused by a gene change (mutation) that can be passed from parent to child.

12 in 100 metastatic prostate cancers (when the cancer has spread from the prostate gland to other parts of the body) are caused by a gene mutation. 

This is known as an inherited germline mutation, and increases the risk of developing cancer.

In some families, where there is an inherited mutation, we see more cases of prostate (and other types) cancer, than we would expect to see by chance. Women in the family might have a higher risk of breast and ovarian cancers.

Genes commonly tested and cancer risk

Genes are ‘coded messages’ which give instructions for how cells grow and function. Some genes give instructions about the colour of hair, or eyes. Some give the body instructions to help protect us from getting cancer.

Genes come in pairs. We all have 2 copies of each gene, because we inherit 1 copy from each of our parents. A germline mutation in 1 copy of a gene causes an increased risk of cancer for people who carry it.

If you are offered germline testing you might be offered testing for several genes or only 1. The normal function of the genes tested is to protect us from developing cancer.

Germline mutations in the following genes are associated with an increased lifetime risk of prostate and other cancers.

BRCA1

Men with a germline mutation in the BRCA1 gene have a 15 in 100 risk of developing prostate cancer. They also have a slightly increased risk, of 1 in 100, of developing male breast cancer.

BRCA2

Men with a germline mutation in the BRCA2 gene have a 25 in 100 risk of developing prostate cancer. They also have an 8 in 100 risk of male breast cancer. Men with a BRCA2 gene mutation have a small risk (3 in 100) of pancreatic cancer.

ATM

Men with a germline mutation in the ATM gene have an increased risk of developing prostate cancer, and the prostate cancer might develop at a younger age. The link to prostate cancer has only recently been identified and so specific associated risk figures are not yet available.

CHEK2

Men with a germline mutation in the CHEK2 gene have an increased risk of prostate cancer. The link to prostate cancer has only recently been identified, so specific associated risk figures are not yet available.

MLH1, MSH2, MSH6, PMS2

Germline mutations in these genes are associated with a condition called Lynch syndrome that can also be associated with an increased risk of prostate, colorectal and other cancers.

Possible results of germline gene testing

Testing does not find a germline mutation

If you had the test because a mutation was identified in your tumour, this result means that the mutation happened by chance and is not something you were born with. We would not offer testing to your family members because we have not identified an inherited mutation.

If you had the test because you have a family history of cancer, this result means the chance of a gene mutation being responsible for your medical family history is small. If you have a family history of cancer, there might be other genetic factors involved.

Testing finds an ‘unclassified variant’ in your prostate cancer susceptibility genes

This means you have a variant in one of your genes, but we do not know if this is significant. This happens in about 1 in 20 (5%) cases.

In the future, medical research might be able to tell us if these variants relate to a family history of cancer, but that level of science is not currently available. We will not be able to use this test result to make decisions about cancer risk management for you or other family members.

A gene mutation is found

This confirms you have an increased chance of getting prostate, and possibly other, cancers. You will be referred to the clinical genetics team to discuss what this means for you and your family. They will also discuss how to pass this information on to your family members.

Making a decision

Deciding to have germline testing can be a difficult and complex process. You might want to think about these points before you have a test.

There are no right or wrong answers to these questions, but it might be a good idea to think about what your answers might be. It means that you might have ideas on what to do when you get your results.

Timing

• Why are you having the test now?
• Will it change your immediate treatment?
• What other challenging events are happening in your life?

Psychological impact of knowing

• How would you feel if an inherited gene mutation was identified?
• How would you share this information with your family, including parents, siblings (brothers and sisters), and children?

Assessing your own coping strategies

• How have you dealt with difficult situations in the past?
• What strategies do you use to help you deal with difficult news?

Next steps

• What might you do to address your risk of cancer if you do have an inherited gene mutation?

Support

Having genetic testing, and receiving the results, can be a challenging time. Some people want to talk through their feelings, coping strategies and other issues before making a decision, or after receiving their result.

Several support options are available, including:

• your genetics clinician
• support groups
• clinical psychologist
• your GP
• cancer charities such as Prostate Cancer UK and Macmillan Cancer Support

Your genetics clinician will discuss these with you in more detail so you can work out what would be best for you.

There is a specialist Hereditary breast and ovarian cancer (HBOC) family service at Guy’s Hospital. This can also be accessed by people who carry an inherited gene mutation, which causes an increased risk of breast, ovarian and prostate cancer. Men with a BRCA2 mutation would be eligible for prostate screening through this service.

Research studies

Whatever your result is, there might be a chance for you to take part in research. Your oncologist or a research nurse will discuss this with you.

Support and more information

Prostate Cancer UK 

Macmillan Cancer Support