Genetic testing for Lynch syndrome will involve having a blood test. DNA will be extracted from your blood to look for genetic changes (or variants) that cause disease or increase your risk of developing a disease. This testing takes approximately three months to complete.

Genetic testing for Lynch syndrome helps your doctors to understand you and your family’s risk of developing cancer in the future. Positive test results will also help your doctors to understand the treatments you may require. They will use it to develop an enhanced cancer prevention programme just for you. If you have cancer, you will be eligible for therapies that are known to work best for people with Lynch syndrome, such as immunotherapy.

Having genetic testing is optional. Your decision will not affect the standard of care you receive. However, knowing you have Lynch syndrome will give you and your family access to personalised cancer prevention programmes, advice and treatments. It will also enable testing of other family members and, if appropriate, they will also be provided with a personalised cancer prevention programme to help reduce the chance of further cancers developing in the family.

Genetic results

Genetic test results do not always give a clear answer. This is because the science of genetics is still in its infancy. For this reason, and for clarity, your results will be classified as positive, uncertain or negative:

  • Positive: a genetic change for Lynch syndrome is identified
    This result would confirm the diagnosis of Lynch syndrome and provide an explanation for why you developed cancer. Your cancer team will use this information in their management decisions and will discuss this with you further. You might be considered for additional therapies, and they will offer predictive genetic testing to your first-degree relatives (parents, siblings and children), as they might carry the same genetic change.
  • Uncertain: Genetic change (or variant) of unknown clinical significance is found
    A genetic change is found, however it is not certain that it is the cause of your cancer. If appropriate, there may be further analysis of your tumour or other family studies recommended. Unfortunately, genetic testing cannot be offered to your family members at this time but cancer surveillance for you and your family will still be recommended.
  • Negative: No genetic changes were found
    This result doesn’t rule out an inherited condition. It might be that the limited knowledge we have about genetics means we are unable find a genetic change currently. If appropriate, there may be further analysis of your tumour recommended, to try to clarify if you have Lynch syndrome. Unfortunately, genetic testing cannot be offered to your family members but cancer surveillance for you and your family will still be recommended. Screening recommendations for you and your family will follow the Lynch-like syndrome recommendations, which your clinician will tell you about.