Certain inherited genetic syndromes:
About 5–10% of people who develop colorectal cancer have inherited changes (mutations) in their genes (the functional units of our genetic material, also known as DNA) that can lead to them getting the disease. These are often associated with people having colorectal cancer at a younger age than average. The most common hereditary conditions leading to colorectal cancer are:
- Lynch syndrome: This is the most common hereditary syndrome leading to colorectal cancer. It accounts for about 3–5% of all colorectal cancers. The lifetime risk of colorectal cancer in people with this condition is 20–70%.
Lynch Syndrome Ireland 