Family History of Cancer: What to Ask and Why It Matters
You don’t need an elaborate family tree to start understanding whether cancer might run in your family. A few details can be surprisingly helpful: who had cancer, what type it was, roughly how old they were, and whether they’re related through your mum or dad.
Why does family cancer history matter?
Most cancers happen by chance or as a result of a combination of factors, including age, lifestyle and environment. But sometimes, cancer risk runs in families because of an inherited genetic change.
Knowing which relatives have had cancer, what type they had and how old they were when diagnosed can help your doctor identify whether there might be an inherited risk.
And importantly, knowing your family history can make a difference to what happens next. You might qualify for genetic testing, need screening at an earlier age or benefit from steps to reduce your risk.
That’s why it’s worth asking questions about your family’s cancer history, even if everyone in your family is currently well.
Can you have an inherited cancer risk without a family history?
Yes. Although family history can help identify people at increased risk, it isn’t a foolproof way of finding everyone who carries an inherited cancer-risk gene.
Some families are small, people may not know their relatives’ medical history, and not everyone who inherits a genetic change will develop cancer.
This means you can carry an inherited cancer-risk gene even if nobody in your family has ever been diagnosed with cancer.
Having no family history doesn’t necessarily mean you have no inherited risk.
And it’s one reason why some people choose to explore private genetic testing, even when they don’t meet NHS testing criteria.
Who should I ask?
Start with parents, siblings and children (first-degree relatives), then grandparents, aunts, uncles, nieces, nephews, grandchildren and half-siblings (second-degree relatives). Include both sides of the family. A father can pass on a gene change without ever developing cancer himself, including for breast cancer genes like BRCA1 and 2.
What information should I collect?
For anyone who has had cancer, write down their relationship to you, which side of the family they’re on, the cancer type and approximate age at diagnosis. If you know whether they had more than one cancer or have an old genetic test report, add that too. It’s fine to leave gaps.
How do I start a sensitive conversation?
It doesn’t have to be a formal conversation. You might say: ‘I’m trying to understand our family medical history a bit better. Do you know which cancers people in the family had, and roughly when?’ Explain why you’re asking, and respect anyone who would rather not discuss it.
What if my family history is unknown?
Not everyone has access to this information. Families may be small, relatives may be estranged, or you may be adopted. Not knowing your family history is not the same as having a reassuring family history. Your doctor can still consider your own health and other relevant factors.
What deserves a closer look?
It’s worth asking for advice if cancers have occurred unusually young, several relatives on the same side have been affected, different related cancers have occurred, or someone has had a rare cancer or more than one primary cancer. A known inherited gene change is another important clue.
It’s important to know that even different cancers, for example prostate and breast cancer in the same family, can have a common genetic link.
Should I update the history?
Yes. If someone else in the family develops cancer or a relative has a genetic result, add it to your notes. You can ask your doctor whether that changes your risk assessment. And keep attending routine screening in the meantime.
What should you do next if cancer runs in your family?
Once you’ve started putting together your family cancer history, the next step is understanding what it might mean for you.
1. Talk to your GP
You don’t need a perfect family tree before asking for advice. If you’ve noticed several relatives with cancer, someone diagnosed unusually young or a combination of cancers that concerns you, bring the information you have to your GP.
They can help assess whether a referral to an NHS genetics service might be appropriate.
Find out who may qualify for NHS genetic testing.
2. Consider whether genetic testing would be useful
You don’t necessarily need a strong family history to consider genetic testing. Sometimes inherited cancer risks are passed down through smaller families or relatives who have never developed cancer.
Private testing may be an option if you don’t meet NHS criteria or would prefer to explore your risk independently. But choosing the right test matters, and testing an affected relative first may sometimes provide a more useful answer.
Explore private inherited cancer genetic testing
3. Think about what you could do with the information
Finding out you’re at increased risk doesn’t mean you’ll develop cancer. It may mean there are things you can do differently.
Depending on your risk, these could include starting screening earlier, having more frequent checks, considering risk-reducing medication or surgery, or making changes to factors that influence your health.
Even if genetic testing doesn’t identify an inherited risk, your family history may still be relevant to your screening and prevention plan.
Finding risk earlier creates choices
At Coyne Medical, we believe that knowing more about your inherited cancer risk can help you make informed decisions about your future health.
Our doctor-led genetic testing service includes a consultation before testing and a follow-up appointment to explain your results, discuss ways to reduce your risk and arrange further screening or specialist referrals where appropriate.