The genetic risk for colon and rectal cancer.
- The risk of developing colorectal cancer increases 2-3 times when a parent, sibling, or child is diagnosed compared to those with no family history.
- The risk increases 3-6 times over the general population, when a relative is diagnosed at a young age or if there is more than one relative with colorectal cancer.
- About 20% of all colorectal cancer patients have a close relative who was also diagnosed with the disease.
- About 5% of patients with colorectal cancer have a well-defined genetic syndrome that causes the disease like Lynch syndrome or familial adenomatous polyposis (FAP). These conditions are linked with higher risks for colon and other cancers.
- Lynch syndrome accounts for 2- 4% of all colorectal cancer cases.
- FAP is the second most common predisposing genetic syndrome; for these individuals, lifetime risk of colorectal cancer approaches 100% without intervention.
Lynch Syndrome Ireland 