Lynch syndrome is an inherited condition that makes people more likely to develop particular types of cancer. In order to explain Lynch syndrome, we need to explain how normal cells work and divide, and how cancer occurs.

For our body to grow and repair itself, cells must create new cells. If you cut yourself, your skin cells continue to divide until the wound is healed. Normal healthy cells know when to stop dividing. Cancer happens when cells continue dividing when they are supposed to stop. As the cancer cells grow, they begin to crowd out normal cells and eventually form a lump. A lump of cancer cells is called a tumour.

There are some mechanisms in our body that protect us against cancer. These mechanisms guard cells and make sure that the cells know when to stop dividing. When these mechanisms identify cells that are unable to stop multiplying, these mechanisms repair or remove these cells, and by doing so they prevent cancer from occurring. One of these mechanisms is created by the DNA mismatch repair genes called MLH1, MSH2, MSH6 and PMS2.

Everybody has these genes. In Lynch syndrome, one of these genes is not working properly. This means that their cancer protection mechanism is not working at 100%, and so people with Lynch syndrome have less protection against cancer.

These mismatch repair genes work like police officers in our body, checking that cells are made properly and don’t divide and multiply out of control. If these genes aren’t working properly, it might result in fewer police officers, which results in less protection against cancer.

This means that people living with Lynch syndrome have less protection, rather than having a genetic alteration that causes cancer itself. For this reason, not all individuals living with Lynch syndrome will develop cancer, but having less protection makes it more likely. Most people living with Lynch syndrome live a normal life.

Lynch syndrome is caused by a genetic change in one of these DNA mismatch repair genes called MLH1, MSH2, MSH6 and PMS2. There is a fifth gene involved called the EPCAM gene because it turns off the neighbouring MSH2 gene. EPCAM alterations are very rare and only account for 6% of Lynch syndrome cases.

The main concern in Lynch syndrome is colorectal (bowel) cancer. For women, endometrial (womb) cancer is also a concern, and to a lesser degree ovarian cancer. There is small increase in the likelihood of developing a few other cancer types that you may need to keep an eye on, but this will be explained later. The risk or likelihood of developing different cancer types depends on which gene is implicated, and other factors such as gender and age.

Having a diagnosis of Lynch syndrome can be a double-edged sword. On one hand, it could be worrying to know that you have a higher likelihood of developing cancer. On the other hand, you are armed with knowledge and an enhanced screening programme that will help you prevent these cancer types and live a normal and fulfilling life. It will empower you to manage your care. Monitoring and screening will help to prevent cancer, or help to diagnose and treat it early.

It is important to know that you are not alone. As many as 1 in 278 people live with Lynch syndrome. There are over 7 billion people on earth. Over 25 million of them have Lynch syndrome, just like you.

If you would like to meet other people living with Lynch syndrome, there is association called Lynch Syndrome UK run by people living with Lynch syndrome. They have useful resources, organise events, and have online as well as face-to-face support groups where you can meet people just like you.