Lynch syndrome used to be known as hereditary non-polyposis colorectal cancer (HNPCC), but the condition can increase the risk of many different types of cancer, including certain types of ovarian cancer. The definition of Lynch syndrome is still evolving as we understand more about it.

Our cells produce proteins that help to repair damaged DNA, which could otherwise cause a cell to multiply out of control and form a tumour. If the gene for one of these proteins has a spelling error or change, the protein may not work properly or at all. DNA damage is therefore more likely to accumulate, so the cell can become a cancer cell.

One of the ways in which cells repair damaged DNA is called mismatch repair. You can watch a video about the different ways for cells to repair DNA damage, including mismatch repair here.

There are a number of different genes which, if altered or changed, can reduce a cell’s ability to carry out mismatch repair. This is called mismatch repair deficiency, or MMD. The gene changes that cause Lynch syndrome are all types of MMD. The genes involved are called MLH1, MSH2, MSH6, and PMS2. In rare cases changes in another gene, called EPCAM, can also cause Lynch syndrome by affecting MSH2, which is the gene next to it.

Changes in these genes increases the risk of colorectal, ovarian, endometrial (womb), stomach, small bowel, bile duct, gallbladder, pancreas, ureter, kidney, bladder, prostate and brain cancer. These risks vary according to which genes are affected. The lifetime risk of developing ovarian cancer for a a person with ovaries and  with Lynch syndrome can be up to 17%, depending on which of the mutations they are carrying.

You can find more details of the risks from each mutation on page 21 of the Royal Marsden’s beginner’s guide to Lynch syndrome.

The lifetime risk of developing ovarian cancer for someone without these gene changes is around two per cent. The lifetime risk of developing ovarian cancer when you have a Lynch syndrome gene change is listed below:

Gene mutation	Carrier lifetime risk
MLH1	11%
MSH2	17%
MSH6	11%
PMS2	Similar to general population
EPCAM	Unknown

Figures taken from The Royal Marsden Beginner’s Guide to Lynch syndrome

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Who is eligible for testing for Lynch syndrome?

I have been diagnosed with cancer:

Since 2022, the National Genomic Test Directory has stated that everyone diagnosed with high grade non mucinous epithelial ovarian cancer be offered genetic testing to see if they carry a gene change associated with Lynch syndrome. If you have a different type of epithelial ovarian cancer, you may be eligible for genetic testing for Lynch syndrome if you have close family members who have also been diagnosed with epithelial ovarian cancer. If you’ve been diagnosed with ovarian cancer, a diagnosis of Lynch syndrome won’t affect your treatment options. Ovarian cancer caused by Lynch syndrome is managed in the same way as non-hereditary ovarian cancer. 

NICE recommends that the tumours of all people newly diagnosed with colorectal cancer or endometrial (womb) cancer should be assessed for features of Lynch syndrome. If this test indicates Lynch syndrome is the cause of the cancer, the person should be offered a blood test to find out if they carry a gene change in every cell of their body (known as germline testing).

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I haven’t been diagnosed with cancer
If you haven’t been diagnosed with cancer but are concerned about your family history, your GP will be able to advise you on whether you’re eligible for genetic testing. They can refer you to your local genetics service who will talk you through the test before you decide whether to go ahead. If genetic testing confirms that you carry a gene change, the genetics service can explain what this means for you and your family and ways of managing your individual risk.

The National Genomic Test Directory lays out clearly who can access testing for Lynch syndrome, but it is complicated to understand. As a rough guide you may wish to speak to your GP if you have:

• Two or more relatives on the same side of the family with colorectal or Lynch syndrome-related cancers
• Any family members diagnosed with colorectal cancer or Lynch syndrome-related cancers under the age of 50 and/or
• Three or more relatives with Lynch syndrome-related cancers on the same side of the family

Ovarian Cancer Action have a risk tool that you can use as a guide to your own risk level based on your medical and family history.

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Managing risk

If you have a gene change associated with Lynch syndrome there are steps you can take to manage your risk of developing cancer. The recommended steps to reduce your risk depend on which mutation you have inherited, but your doctor will be able to advise you further on this. You can find more information here. 

As a general guide:

Screening

People with Lynch syndrome are eligible for bowel cancer screening from the age of 25 or 30 depending on the gene involved. This involves a colonoscopy (using a camera to take pictures of the bowel) every 1-2 years and the removal of any polyps or abnormalities that are found.

Screening for the other Lynch associated cancers has not been proven to be effective. There may be further screening services available in some areas but these are not routinely available across the UK.
 

Although it is not possible to screen for stomach cancer, it is suggested that people with Lynch syndrome are screened for a bacteria that can be found in the stomach called H.Pylori screen. This bacteria can increase the chances of stomach cancer, but if found can be treated with antibiotics.

People with a mutation in the MSH2 gene and a family history of certain types of skin tumours may also have yearly appointments with a dermatologist for skin examinations.

Surgery

At present, the only proven way for women at high risk of cancer of the womb and/or ovary to manage their risk is to consider risk-reducing surgery (removal of the uterus, ovaries and fallopian tubes, known as a Risk-Reducing Hysterectomy and Bilateral Salpingo-Oophorectomy, RR-BSO), usually after their family is complete. If you have not yet had your menopause, this will mean you will experience surgical menopause. There are ways to manage the effects of this and you can discuss these with your medical team.

It is important to be aware that this surgery reduces risk, but does not eliminate risk entirely.

Aspirin

There is ongoing research into whether taking aspirin regularly may reduce the risk of developing cancer for people with Lynch syndrome.

The CAPP2 study showed that 600mg of aspirin taken daily for an average of about two years significantly lowered cancer risk in individuals with Lynch syndrome. This is a large dose of daily aspirin which is not recommended outside of the research study at this time. Further studies are needed to decide the best dose.

The CAPP3 study will aim to address this question.  Until the analysis of the CAPP3 data is complete, NICE recommends that people with Lynch Syndrome take a low dose of aspirin (75mg daily), after discussion with their GP.  

There is further information on research into Lynch syndrome here.

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Symptoms awareness

It is important to be aware of what is normal for you and your body, and discuss any persistent changes with your GP.
Our B.E.A.T campaign raises awareness of the signs and symptoms of ovarian cancer.

If you would like to share your experiences of genetic testing, please comment on this post. If you would like information or support, please contact our Support Line on 0800 008 7054 or email [email protected].

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Further sources of information

The Royal Marsden A Beginners Guide to Lynch Syndrome

Macmillan Cancer Support information on Lynch syndrome

Lynch Syndrome UK is a charity which provides support, information, signposting and listening and educates members of the general public and healthcare professionals.

Lynch Syndrome UK online forum

Lynch Syndrome International

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Last updated July 2023. This page is currently under expert review.