Facts about Lynch Syndrome

This blog post is dedicated to Georgia Hurst (@ShewithLynch) as she is a tireless campaigner on Twitter for those with lynch syndrome and she is constantly trying to raise awareness.

 

This is my first factual blog since my little break so I would just like to reiterate that although I spend about a week researching and writing the factual posts, I am not medically trained so please always consult a doctor if you have any worries about your health.

 

What is Lynch Syndrome?

Lynch syndrome is also known as hereditary non-polyposiscolorectal cancer (HNPCC) and is a type of inherited cancer of the digestive tract. Those diagnosed with lynch syndrome have a significantly increased risk of developing colorectal cancer s well as an increased risk of other cancers such as cancer of the uterus, stomach, breast, ovaries, pancreas, prostate, liver and kidney.

 

Lynch syndrome is a possible diagnosis in families with multiple cases of colorectal cancer and there is an increased chance of a lynch sufferer developing several cancers in their lifetime. Lynch syndrome sufferers are more likely to be diagnosed with cancer at a young age with the average age being around forty five. Their cancer is also more likely to be diagnosed on the right side of the colon.

The diagnostic criteria for lynch syndrome is called the Amsterdam Criteria. This has been modified over time so it includes the various cancers that are seen in families with lynch syndrome. The modified list is as follows:

*Three or more relatives with a lynch syndrome related cancer; one of these relatives must be a first degree relative – i.e. parent, sibling or child)

*At least two generations with cancer (i.e. parent and child)

*One or more cancer cases diagnosed when the person is aged fifty or under

*When Familial Adenomatous Polyposis (FAP) is ruled out as the cause

 

The definition of lynch syndrome is still evolving as more is discovered about it. A family could have lynch syndrome even if they do not meet the above criteria in full. A meeting with a genetics counsellor is advised if you think your family is at risk of lynch syndrome.

Causes of Lynch Syndrome

Lynch syndrome is a genetic condition which means the risk of cancer is passed from generation to generation within a family. There are several genes which have been found to be linked with lynch syndrome including MLH1, MSH2, MSH6, PMS2 and EPCAM. A mutation in any of these genes will give someone an increased risk of developing colorectal cancer in their lifetime as well as increasing their risk of developing other cancer related to lynch syndrome. Women with lynch syndrome will also have anincreased risk of uterine and ovarian cancers.

Most lynch syndrome mutations are found in the MLH1 and MSH2 genes but not all families with lynch syndrome will have mutations in the genes mentioned in the above paragraph and research is still ongoing with this subject. Changes in these genes could also occur due to increased age and there may be other causes which are not yet understood.

How is Lynch Syndrome Inherited?

Every cell normally has two copies of every gene, one which has been inherited from your mum and one from your dad. Lynch syndrome follows something called an autosomal dominant inheritance pattern which means only one of these genes needs to become mutated to give a person an increased risk of getting a particular disease. So if a parent with a gene mutation can either pass along a copy of their normal gene OR a copy of the gene with a mutation. This means a child with a parent who has a gene mutation has a 50% chance of inheriting the mutation.

Is Lynch Syndrome Common?

Colorectal cancer normally occurs by chance and has no known cause but around 3-5% of cases are though to be related to lynch syndrome.

Diagnosing Lynch Syndrome

If a family matches the Amsterdam Criteria then it can be diagnosed via a blood test which will determine if someone has a mutation in any of the genes associated with lynch syndrome.If someone is diagnosed with cancer and their family history indicates lynch syndrome then tests can be performed on the tissue or the tumour to determine if lynch syndrome is likely. These screening tests are microsatellite instability testing (MSI) and immunohistochemistry testing (IHC). These tests will show if more specific genetic testing is required. Genetic testing is normally only advised for patients with a family history that could indicate lunch syndrome as most cases of colorectal cancer are normally random and without a known cause.

 

Cancer Screening for Lynch Syndrome Sufferers:

If you are diagnosed with lynch syndrome then you shouldundergo regular screening. The screening will differ dependingon the person but normally the following will occur:

*You will have a colonoscopy every 1-2 years starting from around the age of 20-25

*Upper endoscopies periodically to check for signs of stomach or intestinal cancer

*Yearly urine cytology screening for urinary tract cancer

Women may also have:

*Yearly pelvic examinations and smear tests as well as transvaginal scans

*CA125 blood tests to check for ovarian cancer

 

These tests do differ so if always check with your doctor if you feel you should be screened for something.

 

As someone who has lost family members ot genetic mutations, I strongly urge anyone with a strong family history of cancer to seek advice from their doctor and/or a genetics counsellor to see if something such as lynch syndrome runs in your family. If your family does have a genetic mutation then it is vital you are aware of it so that you can have regular screening.

 

For more information on lynch syndrome and other types of genetic mutations please visithttp://www.cancerresearchuk.org/cancer-help/about-cancer/causes-symptoms/genes-and-inherited-cancer-risk/inherited-genes-and-cancer-risk/inherited-genes-and-specific-cancers