How can you prevent getting cancer if you know it runs in your family?

Depends on type: It is well know that there are certain cancer types that run in families. This has recently received a lot of publicity with breast cancer. To specifically address your question, start with the family history of cancer. Is there a particular type that shows a pattern? Then check with your physician to see if there are any genetic screening markers (dna markers) that can be done for this cancer.