Cancer itself is not passed from parents to children, but some gene changes that raise the risk of cancer (such as mutations in the BRCA1 and BRCA2 genes) can be inherited [1]. Only about 5 to 10 per cent of cancers are hereditary. The rest come from gene changes that happen during life, with ageing, tobacco smoke, radiation and other factors [2, 3]. Having an inherited mutation means a higher risk, not that you will definitely get cancer [1].
Hereditary, familial or sporadic?
The gene changes that lead to cancer arise in three ways [1]:
- Random mistakes when cells divide
- Damage to DNA from outside factors, such as tobacco smoke, sunlight and the HPV virus
- Inheritance from the father or mother
Most cancers come from random changes building up over the years [1].
Hereditary cancer is uncommon: family members have a higher risk of one or more cancers because of an inherited gene mutation and sometimes develop cancer at a young age. For example, in an inherited bowel condition (FAP), the chance of bowel cancer at a young age is very high [1]. But not every cancer that "runs in the family" is hereditary; shared lifestyles and habits, chance (especially with common cancers such as prostate cancer) or several small gene changes can also be the cause [1].
In a large study of twins, genes explained about a third of the difference in cancer risk between people; this share was higher in melanoma and prostate cancer (more than half) and about a third in breast cancer [6].
Which signs suggest hereditary cancer?
According to the US National Cancer Institute, these signs make hereditary cancer more likely, and it is worth talking to your doctor about genetic counselling [2]:
- A family member has a known inherited mutation
- Cancer at a young age (for example bowel cancer before age 50)
- Several types of cancer in one person
- Several family members, especially first-degree relatives, with the same type of cancer; or breast and ovarian cancer, or bowel and womb cancer, in the same family
- Cancer in both breasts or both kidneys
- Rare cancers, such as breast cancer in a man
Guidelines recommend genetic testing for everyone with these cancers: triple-negative breast cancer, ovarian cancer, pancreatic cancer, bowel cancer before age 50, prostate cancer that has spread, and breast cancer in a man [2].
Talk to your doctor or a genetic counsellor about your family history. It is best for testing to start with a family member who has had cancer [2]. "Home" genetic tests have major limitations and are not recommended for assessing inherited risk [1].
For bowel cancer: if your father, mother, sister, brother or child had bowel cancer or an advanced polyp before age 60 (or two of them at any age), a colonoscopy every 5 years is recommended from age 40, or 10 years before the age of the youngest affected relative, whichever is earlier [7]. For stomach cancer: if someone in your family has had stomach cancer, get tested for Helicobacter (read more).
Related questions
If my father or mother had cancer, will I definitely get it?
How is an inherited genetic test different from a tumour gene test?
An inherited test is usually done on blood or saliva and shows mutations passed on from your parents. A tumour test shows changes that have arisen in the cancer cells themselves and is used to choose medicines. A tumour test sometimes also reveals an inherited mutation, but it does not replace an inherited test [2].
How long do genetic test results take?
Usually about 2 to 3 weeks [2].
Related cancer types
Related questions
References
7 referencesShow all references, 4 with a study cardClose the reference list
Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
- 1
- 2
- 3
- 4Pathogenic Germline Variants in 10,389 Adult Cancers
- 5Risks of Breast, Ovarian, and Contralateral Breast Cancer for BRCA1 and BRCA2 Mutation Carriers
- 6Familial Risk and Heritability of Cancer Among Twins in Nordic Countries
- 7Colorectal Cancer Screening: Recommendations for Physicians and Patients From the U.S. Multi-Society Task Force on Colorectal Cancer
This page is based on reputable scientific sources and was last updated on 28 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.
Printed from the website; the full and up-to-date version: https://drdabiri.com/en/questions/is-cancer-hereditary/