Cancer Genetic Testing
What Is Cancer Genetic Testing?
Cancer genetic testing looks for inherited changes (variants) in genes that may increase a person’s likelihood of developing certain types of cancer. These gene changes can be passed through families, although a family history of cancer does not always mean that an inherited genetic variant is present.
Testing may examine a single gene, such as BRCA1 or BRCA2, or a broader multi-gene panel associated with inherited cancer risk. Depending on the test, a sample of saliva, blood or cheek cells may be used. The result can help clarify whether an inherited genetic factor may be contributing to a personal or family history of cancer.
It is important to distinguish inherited cancer genetic testing from tumour testing. Inherited testing examines the DNA you were born with and may have implications for biological relatives, whereas tumour testing analyses changes within cancer cells to help guide treatment decisions.
At London Genetics, cancer genetic testing forms part of our wider genetic testing services, helping individuals and families access clinically appropriate testing and clear next steps.
A family history of cancer can leave you with more questions than answers. Our Cancer Genetic Testing service analyses your DNA for inherited mutations linked to hereditary cancers, giving you clear, evidence-based insight to guide screening, prevention, and peace of mind.
Who May Benefit from Cancer Genetic Testing?
Cancer genetic testing may be appropriate for individuals with a personal or family history that suggests an inherited cancer predisposition. This does not mean that everyone with cancer, or everyone with a relative affected by cancer, requires testing. The relevance of testing depends on the type of cancer, age at diagnosis, pattern of cancer in the family and, in some cases, ancestry.
You may benefit from cancer genetic testing if you have:
- Been diagnosed with cancer at a younger-than-expected age
- Had more than one primary cancer, or cancer affecting both paired organs, such as both breasts
- A personal or family history of breast, ovarian, prostate, pancreatic, bowel, endometrial or other cancers that may be inherited
- Several close biological relatives diagnosed with related cancers
- A known inherited cancer-related genetic variant in your family
- An ancestry associated with a higher prevalence of particular inherited variants, such as Ashkenazi Jewish ancestry
- A cancer diagnosis where inherited genetic information may help inform screening, risk-reduction options or treatment planning
Not every family pattern has a clear genetic explanation, and a person may still be suitable for assessment even if their family history is limited or incomplete. In some situations, testing an affected relative first can provide the most informative result.
For a broader overview of cancers that can be associated with inherited genetic variants, see our guide to genetics-related cancers. If you are unsure whether testing is appropriate in your circumstances, a cancer genetic counselling appointment can help determine the most suitable next step.
Types of Cancer Genetic Tests and Gene Panels
Cancer genetic testing is tailored to the individual or family history being investigated. The most suitable test depends on factors such as the cancers diagnosed in the family, the age at diagnosis, whether a known familial variant has already been identified and whether a person has previously had cancer.
Single-Gene Testing
Single-gene testing looks for changes in one specific gene. It may be appropriate when a known pathogenic variant has already been identified in the family, or when an individual or family history strongly suggests a particular hereditary cancer syndrome.
For example, targeted testing may be considered for genes including BRCA1, BRCA2, TP53, PALB2 or genes associated with Lynch syndrome, depending on the clinical context.
Multi-Gene Cancer Panels
Multi-gene panels analyse several cancer-related genes at the same time. They are often used where the personal or family history could be explained by more than one inherited condition, or where there is no known genetic variant in the family.
A panel may include genes associated with inherited breast, ovarian, prostate, pancreatic, bowel, endometrial or other cancer risks. The genes included, and the relevance of the results, vary between panels and should reflect the reason for testing.
Targeted Familial Variant Testing
Where a pathogenic or likely pathogenic variant is already known in a biological relative, targeted testing can determine whether that specific variant has been inherited. This is usually more focused than a broad panel and can provide useful information for screening and risk-management decisions.
The aim is not simply to test the greatest possible number of genes. Choosing an appropriate test helps ensure that results are clinically meaningful and reduces the likelihood of findings that are unlikely to change care.
Cancer Genetic Testing: Test Options at a Glance
Cancer genetic testing is selected based on your personal diagnosis, family pattern, and whether a known genetic alteration has already been identified in a relative. The table below outlines the primary inherited cancer test approaches.
| Test Approach | What It Investigates | Clinical Setting & Suitability |
|---|---|---|
| Single-Gene Analysis | Detailed sequencing and deletion/duplication testing of one high-risk gene (e.g. BRCA1, BRCA2, or PALB2). | Best suited when a family history is characteristic of a single hereditary syndrome or initial targeted review is indicated. |
| Targeted Familial Testing | Tests exclusively for the exact pathogenic or likely pathogenic variant already identified in a blood relative. | Ideal for cascade testing in relatives to confirm or rule out the specific inherited risk factor. |
| Tumour-Specific Panels | A curated group of genes associated with a specific cancer type (e.g. hereditary breast, ovarian, or colorectal panels). | Applied when multiple genes can cause overlapping presentations but testing remains focused on one primary disease area. |
| Comprehensive Multi-Gene Panels | Broader next-generation sequencing across multiple hereditary cancer predisposition pathways simultaneously. | Used where family histories involve multiple distinct cancers, unusual presentation ages, or mixed inheritance patterns. |
What Does the Cancer Genetic Testing Process Involve?
The cancer genetic testing process is designed to ensure that the test selected is relevant to your personal and family circumstances, and that the result can be interpreted in a clinically meaningful way.
1. Clinical Information Review
The process begins with a review of relevant information, which may include your personal cancer history, cancers diagnosed in biological relatives, ages at diagnosis and any previous genetic test results within the family. Where available, medical records or a relative’s confirmed genetic result may help identify the most appropriate testing approach.
2. Selecting the Appropriate Test
The laboratory test is selected according to the clinical indication. This may involve targeted testing for a known familial variant, analysis of a single gene or a multi-gene hereditary cancer panel. Testing is not one-size-fits-all: a focused test can sometimes be more informative than a broader panel.
3. Providing a Sample
Most inherited cancer genetic tests are performed using a blood or saliva sample. The sample is sent to an accredited laboratory, where the relevant genes are analysed for inherited variants associated with cancer predisposition.
4. Laboratory Analysis and Result Interpretation
Laboratory findings are assessed alongside the clinical and family information provided. This context matters because not every genetic change has the same clinical significance. Results are generally reported as:
- Positive: a pathogenic or likely pathogenic variant associated with inherited cancer risk is identified.
- Negative: no relevant pathogenic variant is identified through the test performed.
- Variant of uncertain significance (VUS): a genetic change is found, but current evidence is insufficient to determine whether it affects cancer risk.
5. Receiving Your Results and Next Steps
Once the result is available, the next steps depend on the finding and your individual circumstances. This may include screening recommendations, discussions about risk-reducing options, consideration of testing for relatives or communication with your GP and other treating clinicians where appropriate.
What Can Your Cancer Genetic Test Results Tell You?
A cancer genetic test result can help clarify whether an inherited genetic variant associated with cancer risk has been identified. It does not diagnose cancer, predict with certainty whether cancer will develop, or replace routine medical care and screening. The meaning of any result depends on the test performed, your personal history and your family history.
A pathogenic or likely pathogenic variant can indicate an increased inherited susceptibility to particular cancers. The level and type of risk vary according to the gene involved and other individual factors.
Results may help inform whether earlier, more frequent or different forms of cancer screening should be considered alongside your clinical team.
Where an increased inherited risk is identified, the result may support discussions about prevention and risk-reduction options that are appropriate to your circumstances.
If an inherited variant is found, biological relatives may have the option to consider targeted testing for the same familial variant. This can help clarify who may benefit from their own screening or follow-up.
For some people who have already received a cancer diagnosis, inherited genetic findings may also contribute to conversations about treatment options, clinical trials or care planning with their oncology team.
A result provides information, not a diagnosis or certainty. A positive result does not mean that cancer is inevitable, and a negative result does not always remove risk based on personal or family history. The result should be considered alongside your wider clinical picture to determine the most appropriate next steps.
Understanding Positive, Negative and VUS Results
Cancer genetic test results are interpreted in the context of the genes tested, your personal medical history and your family history. A result can provide valuable information, but it should not be viewed in isolation.
Positive Result
A positive result means that a pathogenic or likely pathogenic genetic variant has been identified in a gene associated with inherited cancer predisposition.
This may indicate an increased likelihood of developing one or more specific cancers, although it does not mean that cancer is certain to develop. The implications vary according to the gene involved, the variant identified, your age, medical history and other individual factors.
A positive result may help inform:
- Personalised screening and surveillance plans
- Discussions about risk-reducing options
- Consideration of treatment-relevant information for people with a cancer diagnosis
- Targeted testing for biological relatives
Negative Result
A negative result means that no pathogenic or likely pathogenic variant was identified in the genes analysed by that particular test.
The meaning of a negative result depends on why testing was performed:
- True negative: where a known familial variant has been identified in a relative and you do not carry that specific variant. This can be reassuring, although general population screening advice may still apply.
- Uninformative negative: where no known familial variant is available for comparison. A negative result does not always explain a strong personal or family history of cancer, as current testing cannot identify every possible genetic contributor.
In either situation, screening recommendations may still be influenced by your personal and family history.
Variant of Uncertain Significance (VUS)
A variant of uncertain significance, or VUS, is a genetic change for which there is not currently enough scientific evidence to determine whether it affects cancer risk.
A VUS is not treated in the same way as a positive result and should not usually be used alone to make decisions about increased screening, preventive surgery or predictive testing for relatives. As research develops, some variants may later be reclassified, but many remain uncertain or are eventually found to be benign.
Other Findings
Some tests may identify a benign or likely benign variant. These are genetic differences not considered to increase inherited cancer risk and generally do not require changes to medical management.
The most useful next step is based on the complete clinical picture—not solely the laboratory category. This helps ensure that any follow-up is proportionate to the result and your individual risk profile.
How Cancer Genetic Testing May Inform Screening, Prevention and Treatment
Cancer genetic testing can provide information that helps guide personalised care when an inherited cancer-related variant is identified. The appropriate next steps will depend on the gene involved, the result category, your personal medical history and the pattern of cancer within your family.
Informing Screening and Surveillance
For individuals with an increased inherited cancer risk, cancer genetic testing may support earlier, more frequent or more specialised screening. Depending on the genetic finding and clinical circumstances, this may include breast imaging, bowel surveillance, prostate screening or monitoring for other cancers associated with a particular hereditary condition.
Screening recommendations are individualised. They are based on more than the genetic result alone, including age, personal history and current clinical guidelines.
Supporting Prevention and Risk Reduction
A pathogenic genetic variant does not mean that cancer will definitely develop. However, it may allow individuals to discuss practical ways of reducing risk with their treating clinicians.
These discussions may include:
- Lifestyle and risk-awareness measures
- Enhanced screening to support earlier detection
- Medicines that may be appropriate in specific circumstances
- Risk-reducing surgery for selected individuals with high-risk genetic findings
The benefits, limitations and timing of any preventive option should always be considered on an individual basis.
Contributing to Treatment Planning
For people who have already been diagnosed with cancer, inherited cancer genetic testing may sometimes provide information that is relevant to treatment planning. Certain inherited variants can help oncology teams consider whether particular targeted therapies, clinical trials or surgical approaches may be appropriate.
However, inherited cancer genetic testing is different from tumour profiling. Tumour profiling examines genetic changes within the cancer itself, while inherited testing looks for variants present throughout the body that may also have implications for biological relatives.
Helping Families Take Informed Next Steps
When an inherited pathogenic variant is identified, close biological relatives may be able to consider targeted testing for the same familial variant. This can help identify relatives who may benefit from their own screening, surveillance or risk-reduction discussions—and reassure those who have not inherited the known family variant.
Cancer genetic testing is most valuable when its findings are used as part of a wider clinical plan, rather than as a standalone answer.
Benefits and Limitations of Cancer Genetic Testing
Cancer genetic testing can provide clinically useful information about inherited cancer risk, helping individuals and families make informed decisions about screening, prevention and, in some cases, treatment planning. However, no genetic test can predict cancer with complete certainty or explain every personal or family history of cancer. Understanding both the benefits and limitations of cancer genetic testing is essential.
Clarifying Inherited Cancer Risk
Cancer genetic testing may identify a pathogenic or likely pathogenic variant associated with an increased risk of particular cancers. This can provide a clearer explanation for some personal or family cancer patterns and help distinguish inherited risk from general population risk.
Supporting Earlier Screening and Prevention
When an inherited risk is identified, cancer genetic testing may support discussions about earlier, more frequent or specialised screening. Depending on the genetic finding and individual circumstances, it may also help inform appropriate risk-reduction options.
Providing Information for Biological Relatives
A confirmed inherited genetic variant may allow biological relatives to consider targeted testing for the same familial variant. This can help identify who may benefit from their own screening or follow-up, while providing reassurance to relatives who have not inherited it.
What Cancer Genetic Testing Cannot Confirm
A positive result does not mean that cancer is certain to develop, and a negative result does not always remove risk based on personal or family history. Current testing cannot identify every genetic factor associated with cancer, and some results may identify a variant of uncertain significance (VUS) that cannot guide medical decisions on its own.
Why Choose London Genetics for Cancer Genetic Testing?
Choosing cancer genetic testing involves more than selecting a laboratory test. The value of testing depends on whether the test is appropriate for your circumstances, whether the result is interpreted accurately and whether there is a clear plan for what happens next.
At London Genetics, cancer genetic testing is approached as an individual clinical pathway rather than a standardised screening product. Your personal cancer history, family history and any known genetic findings in relatives are considered when determining the most relevant testing approach.
Testing Selected for Your Clinical Circumstances
A single-gene test, targeted familial test and multi-gene panel can answer different questions. London Genetics helps ensure that the testing approach reflects the reason for referral, rather than simply choosing the broadest available panel.
Clear, Clinically Meaningful Results
Genetic findings can be complex, particularly where a result is negative despite a significant family history, or where a variant of uncertain significance is identified. Results are considered in clinical context, helping you understand what the finding does—and does not—mean for you.
A Focus on Practical Next Steps
Where appropriate, cancer genetic testing results can help inform discussions around screening, surveillance, prevention, treatment planning and testing for biological relatives. The goal is to turn genetic information into a clear and proportionate next-step plan.
Support for Individuals and Families
Inherited cancer risk can have implications beyond the person being tested. When a familial variant is identified, relatives may also need reliable information about whether targeted testing could be relevant to them. London Genetics supports a considered approach to these wider family implications.
Independent and Personalised Care in London
London Genetics provides a personalised route for individuals seeking cancer genetic testing in London, whether they have a personal cancer diagnosis, a known familial variant or concerns about an inherited pattern of cancer in their family.
Book Cancer Genetic Testing in London
Cancer genetic testing can help clarify whether an inherited genetic variant may be contributing to a personal or family history of cancer. The most appropriate test depends on your individual circumstances, including the cancers in your family, ages at diagnosis and any known genetic findings in relatives.
Take a Clinically Appropriate Approach to Testing
At London Genetics, cancer genetic testing is selected to answer a clear clinical question. Whether you are seeking testing following a cancer diagnosis, have a known familial variant or are concerned about an inherited pattern of cancer, the aim is to identify the testing approach that is most relevant to you.
Understand Your Results and Next Steps
Your result may help inform discussions about screening, surveillance, prevention, treatment planning or testing for biological relatives. A genetic result is considered alongside your wider clinical and family history, so that the next steps are clear, proportionate and relevant to your needs.
Ready to explore cancer genetic testing? Book an appointment with London Genetics to discuss the most suitable testing pathway for you and your family.
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Dr Ehsan Karimiani
In this section you can check frequently asked questions.
What is cancer genetic testing?
Cancer genetic testing looks for inherited genetic variants that may increase the risk of developing certain cancers. It can assess genes linked to hereditary cancer syndromes, including BRCA1, BRCA2, Lynch syndrome-related genes and other cancer predisposition genes.
The test looks for variants present in the DNA you were born with. It is different from tumour profiling, which analyses genetic changes within cancer cells.
Who should consider cancer genetic testing?
Cancer genetic testing may be considered if you have a personal or family history suggesting an inherited cancer risk. This can include cancer diagnosed at a young age, multiple primary cancers in one person, several close relatives with related cancers, male breast cancer, or a known genetic variant in the family.
Not everyone with a family history of cancer needs testing. The most suitable approach depends on the cancer pattern, ages at diagnosis and available family information.
Which cancers can be linked to inherited genetic variants?
Inherited genetic variants can be associated with several cancers, including breast, ovarian, prostate, pancreatic, bowel (colorectal), endometrial, stomach and thyroid cancers. Some rarer cancers and particular combinations of cancers may also indicate an inherited cancer syndrome.
The relevant genes and level of risk vary according to the individual and family history.
Does a positive cancer genetic test result mean I will develop cancer?
No. A positive result means that a pathogenic or likely pathogenic variant associated with increased inherited cancer risk has been identified. It does not mean that cancer is inevitable or that you currently have cancer.
The result can help inform discussions about screening, surveillance and risk-reduction options that may be appropriate for your circumstances.
What does a negative cancer genetic test result mean?
A negative result means that no pathogenic or likely pathogenic variant was found in the genes included in your test.
If a known familial variant has been identified and you do not carry it, this is often called a true negative. However, where there is no known variant in the family, a negative result may not fully explain a strong family history of cancer. Screening recommendations may still be influenced by your personal and family history.
What is a Variant of Uncertain Significance (VUS)?
A Variant of Uncertain Significance (VUS) is a genetic change for which there is not yet enough evidence to determine whether it affects cancer risk.
A VUS is not treated as a positive result and should not normally be used on its own to make decisions about preventive surgery, increased screening or testing relatives. Over time, scientific evidence may allow the variant to be reclassified.
What sample is used for cancer genetic testing?
Most inherited cancer genetic tests use a blood sample or saliva sample. The sample is analysed in a specialist laboratory for inherited variants in the selected gene or genes.
The most appropriate sample and test method depend on the clinical reason for testing.
Can cancer genetic testing help relatives?
Yes. If a pathogenic or likely pathogenic variant is identified, close biological relatives may have the option of targeted testing for the same familial variant. This can help clarify whether they may benefit from their own screening, surveillance or risk-management discussions.
A person who has not inherited a known familial variant may avoid unnecessary genetic follow-up related to that specific variant.
Can cancer genetic testing influence treatment?
For some people who already have cancer, inherited cancer genetic testing may provide information relevant to treatment discussions, surgical planning or eligibility for certain clinical trials.
However, inherited testing is not the same as tumour profiling. Your oncology team determines whether tumour testing, inherited testing or both are relevant to treatment decisions.
Is cancer genetic testing the same as a cancer diagnosis?
No. Cancer genetic testing does not diagnose cancer and cannot predict cancer with complete certainty. It identifies whether an inherited genetic factor may affect the likelihood of developing particular cancers.
Results should always be considered alongside your personal medical history, family history and relevant clinical guidance.
