I have a family history of colorectal cancer. when should i begin testing and how often?

Depends on family: You should see a clinical geneticist to document your family history of colon cancer and look for associated symptoms (e.g., dark skin, eye, tooth changes in gardner syndrome). The family pattern (e.g., autosomal dominant or multifactorial) and type of colon cancer (usual older age or early onset as cancer syndrome) will guide testing (blood sent to labs such as myriad genetics).

10 years earlier: The general recommendation is to get a colonoscopy at an age 10 years younger than the youngest age of your first degree family member when they were diagnosed. For example, if your mother was diagnosed with colon cancer at age 48, you should have a colonoscopy at age 38. The frequency depends on what they find at that 1st colonoscopy. If you have fap or lynch syndrome in your family, earlier.