continues. first, you don't want to miss this. one rookie is getting ready for the super bowl after making a comeback from cancer. dr. sanjay gupta begins right now. >>> this morning a doctor getting a lot of attention saying he knows the key to preventing illness. we all want to know this. it could add years to your life. exciting stuff, but also controversial. explain. we'll sit down and talk to professor henry lewis gates about a test that can help you find your roots. absolutely fascinating stuff. they found my roots back six generations. it can also shed a light on your risk of certain medical conditions as well. first, hey, it's super bowl weekend. new york giants taking on the new england patriots. got your favorite, i'm sure. those of us who care about head injuries can look for a few extra things during the game. i want you to pay attention. for one, we know super bowl ads are the most high profile, most expensive spots to run. the nfl will use one of those