Lynch Syndrome

What is Lynch Syndrome?

Lynch Syndrome (historically known as Hereditary Nonpolyposis Colorectal Cancer – HNPCC) is an inherited condition that increases your risk of a number of cancers including ovarian cancer, cancer of the lining of the womb (endometrial cancer) and bowel cancer.

It is caused by an alteration in a group of genes called mismatch repair genes whose function is to repair errors that may arise in the DNA code which in turn stops people developing cancer. Some other cancers may also be associated with Lynch Syndrome such as, stomach cancer, certain types of kidney/ urinary tract cancers, small bowel cancer, brain tumours, etc.

Lynch Syndrome is associated with a fault/ alteration in one of the following mismatch repair genes:MLH1, MSH2, MSH6, PMS2 and EPCAM genes

Families that have Lynch Syndrome usually have more cases of colon (bowel) or womb cancer than would typically be expected. A number of these cases may occur at an earlier age (under 50) than they might in the general population.

If you have a family history of colon or womb cancer and have concerns about this, speak to your GP and ask for a referral to your local genetics centre.

Cancer Type General Population Risk Lynch Syndrome
Ovarian cancer 2% 6 – 14%
Colorectal cancer 7.1% (men) 5.2% (women) 30 – 75%
Stomach cancer 1.5% (men) 0.7% (women) 2 – 13%
Endometrial / womb cancer 2% 25 – 60%
Urinary tract N/A 2 – 11%


Women with Lynch Syndrome are at increased risk of both womb cancer and ovarian cancer. Hence, for surgical prevention, they are offered both hysterectomy (removal of the womb) together with removal of the fallopian tubes and ovaries (salpingo-oophorectomy) from the age of 40 once her family is complete.

For women who wish to have more children, a hysteroscopy and biopsy can be performed once a year to screen for womb cancer, until she is ready to have surgery. A hysteroscopy involves passing a fine telescope through the neck of the womb (cervix) to have a look inside to ensure the lining looks healthy. A small sample of the lining of the womb (biopsy) can be taken at the same time to be sent to the lab to ensure there are no abnormal cells present. While screening for womb cancer has been shown to pick up cancer early as well as at a pre-cancerous stage, it is not yet known whether this process saves lives.

Because Lynch Syndrome also increases the risk of bowel cancer, a bowel check every 2 years is recommended. A colonoscopy is the best way to check the bowel and involves passing a long flexible tube with a small camera at the end of it through the anus (back passage) to look for abnormalities.

There is also evidence showing that taking aspirin reduces the risk of developing bowel cancer and other cancers in women with Lynch Syndrome. The CaPP3 study is focusing on finding the optimum dose of aspirin to give to women with Lynch Syndrome. To find out if you are eligible to take part in the study, please click here.