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BowelGene - Genetic testing for bowel cancer

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Download the BowelGene brochure

BowelGene looks at 12 genes which cause an increased risk of bowel cancer. The following genes are tested.

Gene

Condition

Estimated bowel cancer risk by age 70

EPCAM

Lynch syndrome

25-70%

MLH1

Lynch syndrome

MSH2

Lynch syndrome

MSH6

Lynch syndrome

PMS2

Lynch syndrome

MUTYH

MUTYH associated Polyposis

43-100%

APC

FAP

AFAP

>90%

70%

BMPR1A

Juvenile Polyposis Syndrome

10-38%

SMAD4

Juvenile Polyposis Syndrome

PTEN

Cowden syndrome

9%

STK11

Peutz Jeghers Syndrome

39%

GREM1

Hereditary mixed polyposis syndrome

increased risk

BowelGene is a genetic test for bowel cancer which examines the DNA code for 12 genes known to cause an increased risk of bowel cancer. It is performed on a blood sample and if possible it is always more informative to test a relative who has had bowel cancer.

What is hereditary bowel cancer?

Bowel cancer (also known as colorectal cancer) is the fourth most common cancer in the UK. Unfortunately 1 in 19 women and 1 in 14 men will develop bowel cancer during their lifetime, with most being diagnosed after the age of 50. This means that in the general population men have a 7% lifetime risk of developing bowel cancer and women have a 5% risk. Most bowel cancer occurs by chance, however 2-5% of bowel cancer is inherited and up to 30% is familial. In some families' stomach, womb (endometrial or uterine) and ovarian cancer can also be genetically related to bowel cancer. In families where bowel cancer is hereditary it may be possible to find the genetic change (mutation) which is responsible for the cancers. This allows appropriate cancer screening and risk-reducing options to be offered to the family.

What are genes?

 Genes are the body’s instructions and determine how the body develops and is maintained. Some genes prevent cancer developing: if there is a mutation in one of these cancer genes, then the gene doesn’t work correctly and causes an increased risk of cancer.  Mutations in at least 12 genes can cause an increased risk to bowel cancer and other cancers. However, we know that there must be other genes which are also associated with bowel cancer and research is attempting to find these.

What is BowelGene?

BowelGene looks at 12 genes which cause an increased risk of bowel cancer. 

How does the test work?

BowelGene is performed on a blood sample and it usually takes 4-6weeks to obtain the results. BowelGene uses state of the art NextGeneration sequencing to examine the code
for each of the 12 genes in detail. In addition, dosage analysis is used to look for large deletions (missing parts) and duplications (extra parts) of the genes. It is a
comprehensive way to assess a person’s risk for hereditary bowel and associated cancers. However, no test is 100% and it is possible that someone could have a genetic
mutation which is not detected by this test. It is most accurate to perform genetic testing on someone who has had bowel cancer so that a possible genetic cause can be
found in the family. If this is not possible, genetic testing can be performed on someone who has not had cancer, although if the results are normal this will not be as
informative.

How do I know if I am at risk?

Families with hereditary bowel cancer generally show one or more of the following:

  • Bowel cancer diagnosed at a young age (before the age of 50)
  • Several relatives with bowel cancer
  • Relatives with bowel cancer and related cancers (such as womb or ovarian cancer)
  • Multiple bowel polyps* in an individual
  • Multiple generations with cancer

* Cancer usually starts as a benign growth known as a polyp. Not all polyps will become cancerous and they can often be removed  during screening.

How can genetic testing help?

Genetic testing can help determine the risk of cancer within a family and guide appropriate cancer screening. Depending on the specific genetic risk different screening tests can be arranged and risk-reducing strategies considered. Colonoscopies in particular have particularly been shown to lower the risk of bowel cancer in families with an inherited risk.

 

Lynch syndrome (LS): Lynch syndrome is the most common hereditary bowel cancer syndrome and is the cause of approximately 1–3% of all bowel cancer. LS causes an increased risk of bowel (25-70%), womb (30-70%), ovarian (10%), stomach (5%), prostate (18- 30%) cancerand other cancers. It has been estimated that in Europe approximately one million people have LS.
If someone has LS, regular bowel screening with colonoscopy is vital and other risk-reducing strategies will be considered. These strategies include detecting and treating an infection called Helicobacter Pylori as well as taking aspirin, and consideration of risk-reducing surgery.

Familial Adenomatous Polyposis (FAP) and Attenuated Familial Adenomatous Polyposis (AFAP): FAP and AFAP are inherited conditions which cause multiple  bowel polyps (over 100 in classical FAP), as well as a significantly increased risk of bowel, small bowel (4-12%) and other cancers. These conditions are rare: approximately 2-3 people in 100 000 will have FAP. However, about 25% of people with FAP will have a new mutation in the APC gene: this means that it occurred for the first time in them and so they usually won’t have a family history of cancer. If someone has FAP screening can begin in their teens and they usually consider having their bowel and rectum removed.  AFAP seems to be milder with people having fewer polyps and usually a later age of onset and would need increased bowel screening.

MUTYH Associated Polyposis (MAP): MAP is unusual in that it is inherited in a recessive pattern. This means that someone must inherit a mutation from their mother AND father to be affected. MAP causes multiple bowel polyps, an increased risk of bowel cancer and possibly other cancers. Someone with MAP would be advised to have regular bowel screening.

Juvenile Polyposis syndrome (JPS): Juvenile polyposis causes many polyps in the bowel and most people will develop some polyps by the age of 20. As well as an increased risk of bowel cancer JPS also increases the risk of stomach cancer (21%) and possibly other cancers. Colonoscopy and endoscopy screening will be recommended. 22% of people with SMAD4 mutations will also have hemorrhagic telangiectasia (malformations of the veins).

Peutz Jeghers Syndrome (PJS): PJS causes polyps in the large and small bowel, as well as ovarian tumours and abnormal colouring of the skin in childhood, particularly on the lips. PJS causes an increased risk of bowel (39%), breast (45%), pancreatic (11%) and other cancers. Mammograms, colonoscopies and other cancer screening will be recommended.

PTEN Hamartoma Tumor Syndrome (PHTS)/ Cowden syndrome: Cowden syndrome causes bowel polyps, benign skin lesions, benign breast disease, autism and other features. Individuals with Cowden syndrome have an increased risk of bowel (9%), breast (85%), kidney (34%), thyroid (35%), and womb (28%) cancers as well as a risk of melanoma (6%). Colonoscopy as well as mammograms, renal MRI, skin examination and thyroid ultrasounds will be recommended. Risk reducing surgery may be considered.

Hereditary Mixed Polyposis Syndrome (HMPS): HMPS is a rare condition which has been identified in families of Ashkenazi Jewish ancestry and which causes multiple bowel polyps of different types as well as bowel cancer. Regular colonoscopies are recommended.

 

How are these conditions inherited?

Genes come in pairs; we get one copy from our mother and one copy from our father. Currently most inherited bowel cancer syndromes are inherited in a dominant pattern. This means that if someone has a mutation in one copy of a gene then there is a 50% (1 in 2) chance that they will pass this onto their children. The diagram opposite illustrates this.

What does it mean if I have a mutation?

If you have a mutation this means that you have an increased risk of bowel cancer and possibly other cancers. Your exact risks will depend on which gene mutation has been found. Extra screening and/or risk-reducing strategies will be discussed. It will also be possible to offer predictive testing to other people in your family to see if they also have the mutation.

 

Screening: When someone has an increased risk of bowel cancer it is usual for them to have colonoscopies. A colonoscopy is when a flexible telescope is inserted into the anus to examine the entire bowel (rectum and colon). If any polyps are found these can usually be removed to prevent them developing into cancer. The frequency of colonoscopy will depend on which gene mutation is found. Screening for other cancers may also be needed and will be discussed if necessary. Aspirin has been shown to lower the risk of bowel cancer in some circumstances and is currently recommended for LS carriers.

Risk-reducing surgery: In some situations, people may wish to consider risk- reducing surgery. This is dependent on the condition. In Lynch syndrome women have an increased risk of womb and ovarian cancer and may therefore consider hysterectomy and removal of the  ovaries. Colectomy (removal of the colon) may be considered if an individual has FAP or if they have been diagnosed with bowel cancer.

Bowel awareness: It is important for everyone to be bowel aware and inform their doctor if they notice any signs that they are concerned about.

Signs of bowel cancer are:

  • Bleeding from the anus and/or blood in the stool
  • A change in bowel habit (needing to go to the toilet more less often) lasting for 3weeks, and particularly looser stools
  • Unexplained weight loss
  • Extreme tiredness for no reason
  • A pain or lump in the tummy

Most of the time people with these signs will not have cancer but is always important to get them checked out.

Other risk factors: The risk of bowel cancer increases as a person becomes older which is why bowel screening for the general population currently starts at 60. A personal history of bowel polyps, type 2 diabetes, ulcerative colitis, Crohn’s, and a condition called Acromegaly also increase the risk of bowel cancer and you should consult your doctor regarding screening if you have these.

Lifestyle factors: Smoking and drinking alcohol have both been shown to increase the risk of bowel cancer. Your GP can help with smoking cessation and/or discuss your alcohol intake if you are concerned. Red meat, processed meat, abdominal and body fatness also increase the risk of colorectal cancer. A diet high in dietary fibre, garlic, milk, and calcium lower the risk of colorectal cancer, as does physical activity.

 

Financial Issues

Some individuals may be concerned about difficulties with obtaining insurance coverage following genetic testing. Currently, there is a moratorium ensuring that individuals do not need to disclose predictive genetic test. This moratorium is valid until 2019. More information about insurance can be found at: http://www.abi.org.uk

 

Further information and support can be found at:

http://www.lynchcancers.com
http://community.macmillan.org.uk/cancer_types
/hereditary_nonpolyposis_colorectal_cancer_ hnpcc_or_lynch_syndrome/f/33346/t/51150.aspx
www.corecharity.org.uk 020 7486 0341
www.hereditarycc.org
www.researchuk.org 0808 800 4040
www.macmillian.org.uk 0808 808 0000
www.bowelcanceruk.org.uk 0800 8403540 

Our knowledge of cancer genetics is rapidly growing, and the information given summarises this to date. Please keep us informed of any significant changes in your family in the future as this may alter our advice to you. Please do not hesitate to contact us if you have any questions or concerns

 

Price

At GeneHealth UK we offer genetic counselling to assist you prior to genetic testing for bowel cancer. Our counsellors will provide you with all the information you need to make a decision and will help explain the process of genetic testing to you. Our counsellors will also be available after your test to discuss the results and your options.

The cost for BowelGene is £1500 which includes pre and post test counselling.

If you would like further information and advice on genetic testing  for bowel cancer please contact our team today.

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