Inherited bowel cancer
About inherited bowel cancer
A small number of bowel cancers are linked to gene changes (variants) that can be passed from parent to child (inherited).
A gene variant that increases the risk of bowel cancer can cause a pattern of cancer in a family. Here are some examples of patterns of cancer in a family:
- You have a first-degree relative who was diagnosed with bowel cancer before the age of 50. First-degree relatives are your parents, brothers, sisters and children.
- Your first-degree relative and one of their first-degree relatives both had bowel cancer. They may be diagnosed at any age. For example, this could be your father and his sister (your aunt).
- Relatives on 1 side of your family are affected by certain types of cancer. These types of cancer include:
Or 1 or more relatives may have lots of growths in the bowel. These growths are called polyps.
Worried about inherited bowel cancer?
Bowel cancer is the 4th most common cancer in the UK. Many people have someone in their family who has had bowel cancer. Most cases of bowel cancer are not likely to be caused by an inherited gene variant.
If you are worried about the pattern of cancer in your family, talk to your GP. You should also tell them if a test shows that someone in your family has a cancer gene variant. If needed, your GP will refer you to a genetics specialist. The specialist can give more advice and information. They will explain whether genetic counselling and genetic testing are likely to be useful.
Inherited conditions linked to bowel cancer
The conditions below are caused by gene variants that are linked to a higher risk of bowel cancer and some other types of cancer. If you have one of these conditions, your genetics specialist will explain more about your level of risk. They will also give you information about ways to manage your risk, such as regular bowel screening.
The information they give you will depend on:
- your sex assigned at birth (male or female)
- your age
- the type of gene variant
- your family history
- your medical history
- other factors in your lifestyle.
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Lynch syndrome
Lynch syndrome used to be called hereditary non-polyposis colorectal cancer or HNPCC. It can be caused by variants in several different genes.
People affected by LS have a higher risk of bowel cancer and some other types of cancer, including womb cancer. -
Familial adenomatous polyposis (FAP)
FAP is caused by a variant in the APC gene. This condition causes hundreds or thousands of growths called polyps in the bowel. The polyps usually start to appear when a person is in their teens. If they are not removed, 1 or more of them will almost certainly develop into bowel cancer. Less often, FAP may cause other types of cancer.
Attenuated FAP (aFAP) is a milder form of this condition.
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MUTYH-associated polyposis (MAP)
MAP is a rare condition caused by MUTYH gene variants. This condition causes polyps to develop in the bowel and increases the risk of bowel cancer.
St Mark’s Centre for Familial Intestinal Cancer has more information about MAP.
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Juvenile polyposis syndrome
Juvenile polyposis syndrome is a rare condition caused by variants in 2 different genes. This condition causes growths called juvenile polyps to develop in the bowel and stomach. These increase the risk of bowel and stomach cancers.
St Mark’s Centre for Familial Intestinal Cancer has more information about juvenile polyposis syndrome.
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Peutz-Jeghers syndrome
PTEN hamartoma tumour syndrome is also called Cowden syndrome. It is a rare condition caused by a PTEN gene variant. People affected by this condition have a higher risk of several different cancer types, including a slightly higher than normal risk of bowel cancer.
St Mark’s Centre for Familial Intestinal Cancer has more information about Peutz-Jeghers syndrome.
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PTEN hamartoma tumour syndrome (Cowden syndrome)
PTEN hamartoma tumour syndrome is also called Cowden syndrome. It is a rare condition caused by a PTEN gene variant. People affected by this condition have a higher risk of several different cancer types, including a slightly higher than normal risk of bowel cancer.
PTEN UK & Ireland offers information and support to people affected by PTEN gene variants.
There are likely to be other gene variants that experts currently do not know about. This means genetic tests do not always find a variant in some families.
A family may still have a higher risk of bowel cancer if there:
- is a clear pattern of cancer in the family
- are people who have more bowel polyps than usual
- are people affected by certain types of bowel polyps.
Managing a higher risk of bowel cancer
If your family history or a genetic test shows you have a higher risk of bowel cancer, there may be ways to reduce or manage that risk. Your genetic specialist will explain which of the following might be helpful in your situation:
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Bowel screening tests
You may be offered bowel screening with a test called a colonoscopy. This test checks the lining of the bowel from the inside. You may have this to check for and remove polyps and to look for signs of bowel cancer.
Your genetics specialist will explain whether this test is useful for you. They will say when you should start having it and how often. -
Being aware of the symptoms of bowel cancer
When bowel cancer is found early, it can usually be treated successfully. Contact your GP if you have any symptoms that could be a sign of bowel cancer.
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Risk-reducing surgery and aspirin
In some situations, surgery or taking aspirin can help reduce the risk of cancer developing. This depends on factors such as the gene variant or genetic condition. Your genetics specialist will give you information about this.
We have more information about risk-reducing options and Lynch syndrome or FAP.
If you are offered bowel screening with a colonoscopy, you may have treatment during the colonoscopy to remove polyps. Removing polyps prevents them from developing into bowel cancer.
Sometimes bowel screening shows changes in the bowel that need further treatment with surgery. Your doctor will give you more information about this. -
Lifestyle changes
Your genetics specialist can explain whether factors in your lifestyle affect your cancer risk. If needed, your genetics specialist, GP or practice nurse can give you more information about making healthy lifestyle changes.
About our information
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References
Below is a sample of the sources used in our family history and cancer information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk
Monahan KJ, Bradshaw N, Dolwani S, et al. Guidelines for the management of hereditary colorectal cancer from the British Society of Gastroenterology (BSG)/Association of Coloproctology of Great Britain and Ireland (ACPGBI)/United Kingdom Cancer Genetics Group (UKCGG). Gut. 2020; 69: 411–444. Available from DOI: 10.1136/gutjnl-2019-319915 (accessed October 2022).
NICE. Familial breast cancer: classification, care and managing breast cancer and related risks in people with a family history of breast cancer. Clinical guideline [CG164]. Last updated: 20 November 2019. Available from https://www.nice.org.uk/guidance/CG164 (accessed October 2022).
NICE. Molecular testing strategies for Lynch syndrome in people with colorectal cancer. Diagnostics guidance [DG27]. Published: 22 February 2017. Available from https://www.nice.org.uk/guidance/dg27 (accessed October 2022).
NICE. Testing strategies for Lynch syndrome in people with endometrial cancer. Diagnostics guidance [DG42]. Published: 28 October 2020. Available from https://www.nice.org.uk/guidance/dg42 (accessed October 2022).
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Reviewers
This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Dr Marc Tischkowitz, Reader and Honorary Consultant Physician in Medical Genetics.
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