Genetic testing vs DNA analysis for cancer risk: what’s the difference?
If you have a family history of cancer, you may be considering a test to assess your risk of developing the disease. Before you do, it's important to understand the distinction between genetic testing and commercial 'ancestry-style' DNA analysis.
Ancestry DNA tests, such as those offered by 23andMe and MyHeritage, are commonly used to explore ethnic origins and find biological relatives. They are widely available online and are popular for exploring your ancestry, inherited traits and general wellbeing. They usually examine only a limited number of genetic changes and may miss others. Some services also offer information about personal traits or selected health-related genetic variants. These DNA tests can provide information about your heritage, and some also offer reports on selected health-related genetic changes.
Genetic testing for inherited cancer risk, such as that provided by Check4Cancer, examines relevant genes or known genetic changes, and provides professional interpretation to explain what the findings mean for you and your family. With this clinical genetic testing, a specialist chooses the right test for your personal and family history, and qualified healthcare professionals interpret the results.
This difference matters because, without the right clinical context, the results may cause unnecessary concern or give false reassurance.
This article explains what you need to know about clinical genetic testing vs a commercial DNA test, to help you decide whether clinical genetic testing might be right for you.
Considering genetic testing? Check4Cancer's genetic counselling consultation is a one-hour phone or video appointment with a specialist, who will review your family history and recommend whether testing is right for you.
What is DNA and how can a faulty gene affect your health?
DNA is the genetic information found in almost every cell in your body. It's made up of genes which contain instructions that help your body develop and function.
DNA is written in a code made up of four chemical "letters", A, C, G and T. There are around three billion of these letters in your DNA, and the order they're in makes up your genes. Most of that code is the same from person to person, but at certain positions, people's letters can differ, causing differences in things like eye colour.
A 'genetic change', sometimes called a gene variant, is a difference in the DNA code of a gene compared with the most common version of that gene. Most don't cause health problems, but some can stop a gene from working properly. When this happens, it's sometimes described as a 'faulty gene'.
If you have an inherited gene change that's associated with cancer, it doesn't mean you will definitely get cancer. However, it may mean you have a higher risk of developing cancer, as it affects how cells grow, divide, or repair damaged DNA.
For example, changes in the BRCA genes (BRCA1 and BRCA2) can increase ovarian cancer, prostate cancer and breast cancer risk, including male breast cancer.
What is DNA analysis?
DNA analysis is a broad term for examining genetic data, ranging from single-gene testing to full genomic profiling.
Genotyping: This checks selected points in your DNA where people are known to differ. It's the method most consumer DNA tests use to explore ancestry and inherited traits, and in some cases, to produce general health reports. Because it only checks chosen DNA positions, it can miss genetic changes elsewhere. For that reason, these tests are not a substitute for clinical genetic testing.
Single-gene and gene panel testing: These involve testing full genes, either a single gene or a group, linked to a particular condition. Gene panel testing is the approach most often used to assess inherited cancer risk, such as the risk of developing breast cancer.
Whole genome sequencing: This analyses a DNA sample and reads almost all of your genetic code. In the UK, it's mainly used within the NHS to help diagnose some rare genetic conditions and certain cancers, and in research.
Is genetic testing the same as DNA analysis?
'DNA analysis' is not strictly interchangeable with the term 'genetic testing'.
DNA analysis is a broad term for the technical examination of genetic material.
Clinical genetic testing has a medical purpose, such as examining a specific cancer risk. It's carried out in accordance with clinical guidelines and interpreted by healthcare professionals.
How is genetic testing different from diagnostic testing?
Diagnostic testing, including scans, physical examinations, blood tests and biopsies, is used to confirm or rule out cancer in someone who is experiencing symptoms.
Clinical genetic testing uses a blood or saliva sample to look at a person's genetic predisposition to disease, for example, the risk of hereditary breast cancer. It's also sometimes used after a cancer diagnosis to help inform treatment decisions.
What is the difference between inherited and tumour genetic testing?
Inherited (or germline) genetic testing looks for genetic changes you were born with. It uses a saliva or blood sample and can show whether you have a higher risk of certain cancers.
Tumour (or somatic) testing looks at genetic changes in cancer cells that developed during your lifetime and helps guide treatment. These changes usually aren't inherited, although a tumour result can sometimes suggest that inherited testing is worth considering.
How can genetic testing help you understand your genetic risk of cancer?
Genetic testing can show whether you've inherited a genetic change that raises your cancer risk, which can inform how often you should be screened and help relatives understand their own risk.
No type of genetic testing can account for everything that affects your cancer risk. Non-genetic factors such as age and environment play a part, as do lifestyle risk factors such as smoking, drinking alcohol, and carrying excess weight. That's why it's so important to have a professional assess your genetic test results and consider the full context.
Genetic testing vs DNA analysis at a glance
| Consumer DNA analysis | Clinical genetic testing | |
| Main purpose | Ancestry, traits and general health information | Assessing inherited risk of cancer or other health conditions |
| Who chooses the test | You | A specialist, based on your personal and family history |
| What's checked | Selected points in your DNA | Relevant genes read in full |
| Who explains the results | Usually no one | A genetic counsellor or healthcare professional |
How does cancer genetic testing work?
When you choose genetic testing with Check4Cancer, the process begins with genetic counselling rather than simply ordering a DNA test.
What is genetic counselling and why is it important?
A genetic counsellor is a registered healthcare professional who helps you decide whether genetic testing is right for you. They review your family history, your medical history, and your lifestyle to determine which test would be most helpful.
Genetic counselling also provides emotional support during testing. Your counsellor can help you reflect on how you might feel about your result, and what it could mean for your family.
Your counsellor will explain your result in context and talk you through the next steps, so you aren't left to make sense of your results alone.
The genetic counselling and testing process
You will have a one-hour initial consultation with your genetic counsellor to determine whether testing is appropriate and, if so, which tests to do.
If you decide to go ahead, we will send you a saliva test kit to complete and post to a specialist UK-based laboratory.
You will receive your test results within a few weeks and be invited for a follow-up consultation with your counsellor to ensure you are confident about what the results mean and what the next steps may be.
What do genetic test results mean?
Every result is different, so the steps below are only a general guide to what might happen. Your genetic counsellor will explain what your own result means for you.
- A positive result: If you receive a positive result, it doesn't mean that you will definitely get cancer. It means a clinically significant gene change has been found, which may indicate an increased risk of developing cancer. Depending on the gene change found, your options might include earlier or more frequent screening and advice on ways to reduce your risk. If you've already been diagnosed with cancer, the result may also help guide your treatment.
- A negative result: This means no clinically significant gene change was found in the genes tested. However, it doesn't remove all cancer risk: you'll still have the same risk as anyone else of your age and sex. You may still be offered extra screening based on your family history. You should let your GP know if anyone else in your family is diagnosed with cancer.
- Variant of uncertain significance (VUS): This means a genetic change has been found, but its effect isn't yet understood. This makes it very important for a healthcare professional to interpret the results alongside your family and medical history.
Should I have genetic testing to understand my cancer risk?
Genetic testing for cancer may be worth considering if you have
- a strong family history of cancer
- relatives who were diagnosed unusually young
- several related cancers on the same side of the family
- a relative with a known inherited gene variant, such as BRCA1 or BRCA2
Genetic testing is not necessarily helpful for everyone, and choosing the wrong test could result in limited or confusing information. If you do decide to go ahead, it's important to have genetic counselling first, to find out whether testing is appropriate, and which test will be the most informative.
Genetic testing does not replace recommended cancer screening. If you have symptoms or are concerned that you may currently have cancer, seek medical advice rather than relying on a DNA test or genetic testing.
Need some guidance? Speak to a genetic counsellor at Check4Cancer
Check4Cancer's genetic counselling and testing service is for adults aged 18 and over who are concerned about their inherited cancer risk. Appointments take place by phone or video, and your registered genetic counsellor will support you from your first conversation through to your results and next steps. Our clinical advisors include Professor Andrew Beggs, Professor of Cancer Genetics and Surgery at the University of Birmingham.
Ready to talk it through? Book your initial genetic counselling consultation, a one-hour appointment with a genetic counsellor.
Not sure yet? Get in touch with our team or call 03330 919 650 to ask any questions before you decide.
Check4Cancer is rated 4.8 out of 5 by more than 5,900 patients on Doctify.
Frequently asked questions: genetic testing vs DNA analysis for cancer risk
Can genetic testing diagnose cancer?
Inherited genetic testing cannot diagnose cancer. Cancer diagnosis requires other medical tests, such as imaging, examination or biopsy. Genetic testing is used to assess your inherited risk of cancer, or, if you have already been diagnosed, help inform treatment options.
Does a faulty gene mean I will develop cancer?
No. If you are found to have an inherited gene variant linked to cancer, it may increase cancer risk, but it is not a prediction that you will develop cancer. The level of increased risk depends on the particular gene, the specific change and other genetic, medical and lifestyle factors.
Can a DNA test tell me my lifetime risk of cancer?
A clinical genetic test, rather than a consumer DNA test, can help assess lifetime cancer risk, but it cannot provide the complete picture on its own. Results should be considered alongside your personal and family history by a qualified professional.
What is predictive genetic testing?
Predictive testing looks for a particular inherited gene change in someone who does not currently have the associated condition or any symptoms. It may be offered if a family member is known to have a disease-causing gene variant, or if your history suggests an inherited predisposition.
Can an ancestry DNA test identify an inherited cancer risk?
Consumer DNA tests from ancestry providers may identify some health-related gene variants, but they usually check only a small fraction of the changes linked to inherited cancer. That's why they shouldn't be used to confirm or rule out an inherited cancer risk.
If a consumer test flags a possible health risk, it should be confirmed by a clinical laboratory and explained by a professional in the context of your health and family history. For a clinically meaningful assessment, speak to a genetic counsellor first, who can recommend the right genetic test for you.
