This blog post is from our My Ovacome forum and was originally written in November 2020.

In this post we’ll be looking in more detail at Lynch syndrome, an inherited syndrome that increases the risk of developing certain cancers, including ovarian cancer.

As we mentioned in our first post in this series, 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 mutation, 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 mutated, can reduce a cell’s ability to carry out mismatch repair. This is called mismatch repair deficiency, or MMD. The mutations that cause Lynch syndrome are all types of MMD. The genes involved are called MLH1, MSH2, MSH6, and PMS2. In rare cases mutations in another gene, called EPCAM, can also cause Lynch syndrome by affecting MSH2, which is the gene next to it.

Mutations 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 woman with Lynch syndrome can be up to 17%, depending on which of the mutations she is 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 here.

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. You can read a blog post on Lynch Syndrome on our website here: Lynch syndrome and ovarian cancer | Ovacome

However, as we mentioned above, Lynch syndrome also increases the risk of other cancers. If you think you might have inherited one of the mutations it’s important to discuss your concerns with your team or your GP. If you’ve been diagnosed with colorectal or endometrial cancer, you will be eligible for genetic testing. 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. Ovarian Cancer Action (Lynch syndrome cancer risk) recommend seeing your GP if you have:

•Two or more relatives on the same side of the family with colorectal or Lynch syndrome-related cancers (see the tables above)

•Any family members diagnosed with colorectal cancer or Lynch syndrome-related cancers (see the tables above) under the age of 50 and/or

•Three or more relatives with Lynch syndrome-related cancers (see the tables above) on the same side of the family

They also have a risk tool that you can use as a guide to your own risk level based on your medical and family history, which can be found at

If you do test positive for Lynch syndrome, you may be eligible for screening or risk-reducing surgery, and you can increase your awareness of the symptoms of the different cancers. For example, you will be invited for regular colonoscopies from the age of 25 and you may be advised to have risk-reducing gynaecological surgery.

The recommended steps to reduce your risk depend on which mutation you have inherited. You can find more information here

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]