Cancer And Heredity

Overview

Cancer is a group of diseases where some cells in the body grow out of control. This page explains the links between cancer and family history. It focuses on inherited genetic changes — when a harmful gene change is passed from a parent to a child. While most cancers are not inherited, some families carry changes that can increase the risk of certain types of cancer. Knowing your family history can help you and your healthcare team plan the right screenings and prevention steps for you.

Cancer is common, but inherited cancer syndromes are not. Most people who have a relative with cancer do not carry a high-risk inherited gene change. Most cancers are related to ageing, lifestyle, or environmental factors that happen over a person's lifetime.

Anyone can develop cancer. Inherited cancer risk can affect people of any age, but some warning signs in a family include cancers appearing at unusually young ages, the same type of cancer in several close family members, or one person having more than one cancer. Certain inherited syndromes may also be more common in particular communities.

Symptoms

Common symptoms

• Many hereditary cancer syndromes cause no symptoms by themselves. Symptoms only appear if a cancer has developed.
• Possible warning signs include a new or unusual lump or swelling, changes to a mole, a persistent cough or hoarseness, changes in bowel or bladder habits, unexplained weight loss, or unusual bleeding or discharge.
• These symptoms usually have other causes, but it is always safer to have them checked by a healthcare professional.

Symptoms in children

• Cancer in children is rare, but some children with an inherited risk may show signs such as repeated fevers, bone pain that doesn't go away, unusual bruises, or a noticeable lump.
• These symptoms are far more likely to be due to minor illness or injury, but it is still important to seek prompt medical advice.

Symptoms in older adults

• In older adults, symptoms are more often caused by other health conditions such as arthritis or acid reflux.
• Any new, persistent, or worsening symptom — especially in someone with a strong family history — should be discussed with a doctor.

Causes

Main causes

• Almost all cancers are caused by DNA changes that happen during a person's lifetime. These changes can arise from normal ageing, exposure to tobacco smoke, radiation, harmful substances, or other factors.
• In a small number of families, a harmful gene change is present from birth. This change is passed from a parent to a child, and it increases the risk for certain types of cancer.
• Having an inherited gene change does not mean you will definitely develop cancer. It means your risk is higher than average.

Risk factors

• A strong family history of the same type of cancer, especially in close relatives on the same side of the family.
• Cancers diagnosed at a younger age than typically expected (for example, breast cancer before age 50).
• A relative who has had more than one primary cancer or cancers in both paired organs (such as both breasts or both kidneys).
• A known inherited cancer syndrome in the family, such as certain breast, ovarian, bowel, or skin cancer syndromes.
• Certain ethnic backgrounds that have higher rates of specific inherited gene changes, but this is not a certainty.

When to see a doctor

See a doctor urgently if:

• If you have any new symptom that is severe, persistent, or worsening, contact your doctor promptly — do not wait for a routine appointment.
• If you notice a lump, a changing mole, abnormal bleeding, or unexplained weight loss, seek medical advice within a week or two.

Book a routine appointment if:

• If you are concerned about your family history of cancer, book a routine appointment with your general practitioner to discuss it.
• If one or more close relatives have had cancer, particularly at a young age, ask whether a referral for genetic counselling might be helpful.

Diagnosis

Hereditary cancer risk is not detected through symptoms alone. A doctor or genetic counsellor will review your personal cancer history and your family history in detail. If the pattern suggests a possible inherited syndrome, they may recommend a blood or saliva test to look for specific gene changes. This kind of testing is done after a conversation about what the results might mean.

Tests that may be done

• A detailed family history questionnaire, often drawn as a family tree across three generations.
• Genetic counselling to explain the benefits, risks, and limits of genetic testing.
• A blood or saliva sample to test for specific gene changes linked to hereditary cancer.
• If a gene change is found, you may be offered earlier or more frequent screening tests to monitor for the first signs of cancer.

What to expect at your appointment

If your doctor thinks genetic testing is appropriate, they will usually refer you to a specialist genetics service. You will have a counselling session first. The test itself is simple. Results may take several weeks. You will receive a follow-up appointment to discuss what the results mean for you and for family members who may also be at risk.

Treatment

If you carry an inherited high-risk gene change, treatment or management focuses on lowering your chance of developing cancer and finding cancer early if it does occur. This is often called risk management. Your healthcare team will build a personal plan that considers which cancers you are at risk for, your age, your family history, and your own values.

Self-care at home

• Keep up to date with recommended screening tests, such as breast, bowel, or cervical screening.
• Know the warning signs of cancer and report them to your doctor right away.
• Stay physically active, eat a well-balanced diet, and aim for a healthy weight.
• Avoid smoking and limit alcoholic drinks.
• Protect your skin from sun damage with clothing and shade.

Medical treatments

For some people at very high inherited risk, a doctor may discuss medicines that can help lower the chance of certain cancers. These medicines are not suitable for everyone and have their own benefits and risks. The decision is always shared with your specialist after a thorough review of your personal risk.

When is surgery considered?

In certain inherited cancer syndromes, preventive surgery may be an option. This means removing an organ that has a high chance of developing cancer, such as the breasts, ovaries, or colon. This is a major decision that requires time, genetic counselling, and careful discussion with your specialists.

Living with this condition

Living with an inherited cancer risk can bring a mix of relief, fear, and responsibility. Many people find it helpful to focus on the present — keeping medical appointments, making healthy choices, and staying connected with supportive people. It is okay to ask for help when the worry becomes heavy.

Lifestyle tips

• Aim for 150 minutes of moderate activity each week, such as fast walking, or whatever physical activity feels achievable.
• Choose a variety of vegetables, fruits, wholegrains, and lean proteins. Limit processed meats and sugary drinks.
• Manage stress through activities like mindfulness, gentle exercise, journaling, or talking with a counsellor.
• Limit alcohol to recommended levels and do not smoke.
• Get enough sleep and follow a regular routine as much as possible.

Diet and exercise

There is no single diet that prevents cancer, but eating more plant-based foods and staying physically active can support overall health and help maintain a healthy weight. Ask your doctor or a dietitian for advice tailored to your situation. Regular exercise, like walking or swimming, also improves mood and energy.

Mental health and emotional wellbeing

It is normal to feel anxious, sad, or overwhelmed when thinking about cancer risk. These feelings can affect sleep, appetite, and concentration. If you notice these signs lasting for more than a few weeks, talk to your doctor. You do not have to cope alone. If you ever feel that life is not worth living, please reach out to a mental health crisis service or contact your local emergency number right away.

Prevention

You cannot change the genes you were born with, but you can change many other factors that affect cancer risk. Even if you carry a hereditary gene change, you can still take steps to lower your risk or to find cancer early when it is most treatable. This includes regular screening, a healthy lifestyle, and — in some cases — medicines or preventive surgery.

Vaccines

Vaccination against certain infections, such as HPV (human papillomavirus) and hepatitis B, can lower the risk of some cancers. Talk to your doctor or nurse about which vaccines are recommended for your age and situation.

Screening programmes

Standard cancer screening — such as cervical screening, mammography, and bowel cancer screening — can detect changes before they become cancer, or find cancer at an early stage. If you are known to be at inherited risk, your doctor may recommend earlier or more frequent screening appointments and sometimes imaging tests. Follow the plan agreed with your healthcare team.

Complications

If left untreated

• If an inherited risk goes unnoticed, the first sign of cancer may be a diagnosis at a later stage, when treatment is harder.
• Family members may not have the chance to learn about their own increased risk and take preventive steps.
• Anxiety about cancer can build up without professional guidance, affecting quality of life.

Long-term outlook

The outlook is hopeful. Many people who inherit a cancer risk will never develop cancer. For those who do, surveillance and early detection greatly improve the chance of successful treatment. Knowing your family history and discussing it with your healthcare team puts you in a stronger position than ignoring it. Genetic testing and counselling are continually improving, offering more options for personalised care and peace of mind.

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