Genetic Testing For Inherited Cancer

Overview

Genetic testing for inherited cancer is a blood or saliva test that looks at your DNA. DNA is the instruction book your body uses to grow and repair itself. The test checks whether you carry a change in a gene that makes certain cancers more likely. 'Inherited' means the change can be passed down from a parent to a child. Most cancers are not caused by an inherited gene change, but in some families a gene change plays a big part. Testing is usually done after a conversation with a specialist, so you can understand what the results would mean for you and your family.

Strong inherited gene changes are uncommon. Experts estimate that roughly 5 to 10 in every 100 cancers are linked to a clear inherited factor. Most cancers happen because of random changes in cells over a lifetime, combined with things like age, smoking or other lifestyle factors. So if you do not have a strong family history, testing is usually not needed.

Testing may be offered to people with several relatives who have had the same or related cancers, or cancer at an unusually young age. It can also be offered when someone has had more than one cancer, when a close relative is known to carry a gene change, or when certain ancestries make a specific gene change more likely. Both men and women can carry these gene changes and pass them on.

Symptoms

Common symptoms

• Genetic testing itself causes no symptoms and does not make you feel unwell.
• An inherited cancer gene change on its own causes no symptoms. Symptoms only appear if a cancer starts to grow.
• Clues that lead to testing are usually found in the family tree, not in how you feel — for example, several relatives with the same cancer or cancers appearing at young ages.

Symptoms in children

• Children are rarely tested. Testing is normally only considered for adults, because the cancers linked to these genes usually appear in adulthood.
• In a few rare conditions, testing may be offered to a child if there is a real chance of a cancer developing in childhood and early monitoring would help.
• A genetics team will always talk through the timing with parents and, where appropriate, with the young person themselves.

Symptoms in older adults

• Older adults can still be tested, and results may matter just as much for their children and grandchildren.
• The decision often depends on whether the result would change your own care — for example, whether extra screening would still be useful for you.
• Discussing this with a genetics doctor or nurse helps you weigh up the benefits for you and for your family.

Causes

Main causes

• Inherited gene changes passed from a parent to a child. You inherit two copies of most genes, one from each parent, and a change can come from either side of the family.
• Well-known examples include changes in the BRCA1 and BRCA2 genes, which are linked to breast, ovarian, prostate and pancreatic cancer.
• Changes in the Lynch syndrome genes (with names like MLH1, MSH2 and MSH6) are linked to bowel and womb cancer in particular.
• Other genes such as TP53, PALB2 and APC are linked to other patterns of cancer risk. The gene names are just labels — your genetics team will explain what a specific result means for you.
• Random changes in cells over a lifetime, plus factors like smoking, alcohol and age, cause most cancers. These are not inherited and cannot be passed on.

Risk factors

• Two or more close relatives with the same type of cancer
• Cancer diagnosed before the age of 50, or at an unusually young age for that cancer type
• A relative with two separate cancers, or cancer in both breasts or both kidneys
• Breast and ovarian cancer in the same family, or male breast cancer
• Many bowel polyps, or bowel or womb cancer at a young age
• A known gene change already found in a relative
• Certain ancestries, such as Ashkenazi Jewish heritage, where particular BRCA changes are more common
• A personal history of several separate cancers

When to see a doctor

See a doctor urgently if:

• Any new lump, unusual bleeding, or a change in your body that lasts more than a few weeks
• Symptoms from the emergency and urgent lists above — do not wait for a routine appointment

Book a routine appointment if:

• You have several relatives with the same cancer, or cancer that appeared young in the family
• A relative has been found to carry a gene change linked to cancer
• You are considering testing and want to understand what it would mean for you
• You have questions about your own risk and what screening you might be offered

Diagnosis

Testing is a step-by-step process, not just a blood test. First, a genetics doctor or nurse takes a detailed family history, often going back two or three generations. They explain what a test could show, and what the results would mean for you and for relatives. If testing seems useful, you give consent and a blood or saliva sample is taken. Results usually take several weeks because the laboratory has to read the gene code carefully.

Tests that may be done

• Family history review — which relatives had which cancers, and at what age
• A counselling appointment to discuss benefits, limits and possible results before you decide
• A blood or saliva DNA test — sometimes a single gene, sometimes a panel of several genes
• Predictive testing — if a relative already knows they carry a change, you can be tested just for that one change
• Tumour testing, such as checking a cancer sample for Lynch syndrome patterns, which can point towards testing
• Follow-up appointments to explain the result in plain words and agree a plan

What to expect at your appointment

Possible results include: a gene change was found (a 'positive' result), no gene change was found, or a change of uncertain significance was found — meaning it is not yet known whether it matters. Sometimes the result is unclear and the family history remains the main guide. You should be told in advance what each type of result could mean, and you will have a chance to talk it through afterwards. If you feel anxious while waiting, that is very common — ask the team when to expect the result and who you can speak to in the meantime.

Treatment

There is no treatment that changes a gene you were born with. Instead, care focuses on two things: lowering the chance of cancer where possible, and catching any cancer early when it is easiest to treat. What is offered depends on which gene is involved, your age, your family plans, and what you feel comfortable with. The decisions are yours, made with your specialist team.

Self-care at home

• Keep a written family history — it is genuinely useful to your doctors
• Attend the screening appointments you are offered, even when you feel well
• Get to know how your body normally looks and feels, and report changes early
• Ask for a copy of your results and keep them somewhere safe for relatives who may need them
• Look after general health: not smoking, limiting alcohol, staying active and keeping to a healthy weight
• Tell your doctors about your gene result whenever you have any health appointment

Medical treatments

Approaches usually include closer and earlier screening than the general population — for example, regular breast imaging, bowel checks, or other scans chosen for your gene. Some people are offered risk-reducing surgery, and some are offered preventive medicines after a detailed discussion with a specialist about pros and cons. A genetics or high-risk clinic will build a personal plan with you, review it over time, and involve you fully in each decision. Nothing is done to you without your agreement.

When is surgery considered?

Surgery may be discussed as a way to lower risk — for example, removing breast tissue, or removing the ovaries and fallopian tubes once family planning is complete, or removing the bowel in some rare inherited conditions. These are major operations with real trade-offs, and they are never urgent or compulsory. Some people choose them, many do not, and both choices are valid. Your team should give you time, written information and a chance to talk to others who have faced the same decision.

Living with this condition

Most people with a gene change live full, normal lives. The main practical difference is a schedule of check-ups, and knowing what to watch for. Some people find the appointments reassuring; others find them a reminder they would rather not have. Both reactions are normal. Having your results written down and telling relatives who may be affected can help everyone get the right care sooner.

Lifestyle tips

• Stay physically active in a way you enjoy and can keep up
• Eat a varied diet with plenty of vegetables, fruit and fibre
• Keep alcohol low and do not smoke — both lower cancer risk generally
• Protect your skin from strong sun and avoid sunbeds
• Keep to a healthy weight and get enough sleep
• Have the vaccinations and screening you are offered

Diet and exercise

No diet or exercise plan can remove an inherited risk, but a healthy lifestyle still lowers your overall cancer risk and helps you feel better during screening and treatment. Aim for movement most days — walking counts — and build meals around vegetables, whole grains, beans and fruit, with less processed meat and fewer sugary drinks. Small steady changes beat strict plans you cannot keep up.

Mental health and emotional wellbeing

Learning you carry a gene change can bring worry, sadness, or a sense of being different. Waiting for results is often the hardest part. Some people feel guilt about passing a change on, or worry about which relative to tell. These feelings are common and treatable. Talking to a counsellor, a clinical psychologist attached to the genetics team, or a support group can help a great deal. If you are struggling with your mental health, or having thoughts of harming yourself, please contact your local emergency number or a crisis line in your country straight away — you deserve support right now.

Prevention

You cannot change the genes you inherit. But you can often lower the chance of cancer developing, or find it early, through extra screening, risk-reducing surgery or preventive medicines discussed with your specialist, and through healthy living. That is the real purpose of testing — it turns uncertainty into a plan.

Vaccines

Some cancers are linked to infections that vaccines can prevent. The HPV vaccine helps protect against cervical cancer and some other cancers, and is offered to young people in many countries. Ask your doctor whether you or your children are due it. There is no vaccine against inherited cancer risk itself.

Screening programmes

Screening is the main way testing helps. Depending on the gene, your team may offer earlier or more frequent breast imaging, regular bowel checks such as colonoscopy, checks of the womb lining, or other scans tailored to your risk. Screening usually starts younger than the national programme would for the general population. If you carry a gene change, ask your genetics clinic what your personal screening plan is and how often it should be reviewed.

Complications

If left untreated

• Cancers linked to inherited gene changes may be found later, when treatment is more involved
• Some inherited conditions, such as Lynch syndrome, can also cause growths that need removing if not monitored
• Family members who are not told about a known gene change may miss out on screening that could help them
• Anxiety and uncertainty can grow when there is no clear plan — a plan usually helps a lot

Long-term outlook

The outlook for people with an inherited cancer risk is genuinely hopeful. Most people who know their risk never develop the cancers linked to it, and those who do often have them found early through screening, when treatment works best. Knowing your risk gives you and your doctors options you would not otherwise have. Many people describe the result as a relief — it replaces guesswork with a clear plan they can follow.

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