Genetics

Find out about cancer genetic testing

What are genes?

Genes are the body’s instructions and determine how the body develops and is maintained. Some genes prevent cancer developing: if there is a pathogenic variant (fault) in one of these cancer genes, then the gene does not work correctly and causes an increased risk of cancer.  Variants in several hundred genes can cause an increased risk to specific types of cancer. We also know that there must be other genes that have not yet been identified.

Who is at risk of genetic cancer?

Approximately 5-10% of all cancer is due to a genetic fault (pathogenic variant) which can be inherited. Families with an inherited pathogenic variant may benefit from a cancer risk assessment (genetic counselling consultation), increased cancer screening and/or risk reducing strategies.

Families with an increased risk of cancer often show one of the following clues:

  • Several relatives with the same or linked types of cancer
  • Relatives diagnosed at particularly young ages (usually before age 50)
  • Several affected generations
  • Individuals who have been diagnosed with multiple cancers

There are two main groups of cancers which can be linked in some families. These are:

  • Breast, ovarian, prostate and pancreatic cancers
  • Bowel, womb, stomach, prostate and ovarian cancers

Hereditary cancer risk factors

In general, cancer can be caused by many different factors including family history, medical history and environmental factors. The exact risk factors depend on the type of cancer. For example, lung cancer is usually caused by environmental factors such as exposure to smoke, while cervical cancer often occurs at younger ages but is usually not inherited. 

How does genetic testing work?

Genetic testing looks at the DNA code for a specific gene or genes known to be associated with cancer. It provides information about the gene(s) which are analysed and is usually performed on a blood or saliva sample. Results are normally available in 3-4 weeks. There are several different types of testing available including:

Diagnostic testing

This attempts to find the possible cause of cancer within the family and is performed on someone who has had cancer.

There are three possible results:

  1. Normal: this means no disease-causing variant is found and the cause of the cancer has not been identified.
  2. Positive: a known cancer-causing (pathogenic) variant is found. Cancer treatment can be targeted, and relatives can have testing for this mutation.
  3. Inconclusive: a variant of unknown significance is found. This means the laboratory has found a change in the gene that they cannot interpret.

Pre-symptomatic testing

This looks at several genes to determine if a healthy individual has an increased risk of developing cancer. There are three possible results:

  1. Normal: there may still be an increased risk of cancer depending on your family history and increased screening may still be recommended.
  2. Positive: a known cancer-causing pathogenic variant is found. Cancer screening and risk reduction methods can be targeted, and relatives can have testing for this variant.
  3. Inconclusive: a variant of unknown significance is found. This means the laboratory has found a change in the gene that they cannot interpret.

Predictive testing

When the familial pathogenic variant is known it is possible to give relatives a definitive answer:

  1. If the variant is not present, there is no increased risk of cancer.
  2. If the variant is found, the individual has an increased risk of cancer. Increased cancer screening and risk reducing options may be helpful. 

Should I have cancer genetic testing?

If any of the following are true of your family, you may be at increased risk of hereditary cancer and genetic testing may be of benefit.

  • Several relatives with the same type of cancer
  • Relatives diagnosed at particularly young ages (usually before age 50)
  • Several affected generations
  • Individuals who have been diagnosed with multiple cancers

If you have already had cancer, why would you need genetic cancer testing?

For individuals who have been diagnosed with cancer, they may ask how genetic testing will help.

Depending on the results, genetic testing may help determine the best type of surgery and chemotherapy for you.  In addition, genetic testing can help determine your risk of cancer in future as well as ways to reduce your risk and appropriate cancer screening. Genetic cancer testing can also give your relatives and children information about their cancer risk.

What is a genetic counsellor and what do they do?

Our genetic counsellors will take a detailed family and medical history and will provide you with a personalised cancer risk assessment (your risk assessment will include your personal cancer risk and the risk the cancer in your family is inherited). 

The genetic counsellor will cover the following in your one-hour phone consultation:

  • Ask you about your medical and family history of cancer.
  • Explain how hereditary cancers are passed on in a family.
  • Determine if you/your family members are at risk for a hereditary cancer syndrome.
  • Give you information about inherited cancer syndromes.
  • Discuss cancer screening.
  • Provide information about genetic testing.
  • Allow you to make an informed decision on whether genetic testing is right for you.

If genetic cancer testing is appropriate, the genetic counsellor will explain its benefits and limitations. Cancer screening, such as mammograms or colonoscopies and risk reducing options may also be recommended.

Our pre-test counselling will help prepare you psychologically for testing and ensure you are aware of the implications of the results.

Are Check4Cancer’s genetic cancer tests the same as the ones offered by the NHS?

Yes, our genetic cancer tests use the same technology as those offered through the NHS. The genetic counsellor can provide you with more information.