Transcript for 4-time cancer survivor takes college football field for 1st time
Finally tonight here, America strong. The college football player who waited his entire life to get onto that field, to play college football and he got there. Casey o'brien from St. Paul, Minnesota, has always been a fighter. Playing football since he was a boy. Then, the unexpected. Diagnosed with bone cancer in high school in 2013. He would battle it with chemotherapy, surgery, a knee replacement. Then, on the football team at the university of Minnesota, the cancer would return two more times. He switched from quarterback to holder and because he was fighting cancer, he was still waiting to get on that field. And over the weekend, Casey o'brien, a sophomore now, for the first time, taking the field for Minnesota. Holding the ball for that extra point. Extra point good. That's what college football is all about. Reporter: Hugs from his team and then Casey running over to his coach. Look at this emotional hug with P.J. Fleck. Casey o'brien, a four-time cancer survivor. Reporter: The coach wiping away tears. Casey running over to his mom and dad after the game. And this message from Casey for everyone watching. It means the world to me. There's been so many ups and downs and nights in the hospital and surgeries and everything like that, has gone into this moment that this is what I dreamed about and tonight it got to come true. Don't give up. You can make it happen. Don't give up. The incredible Casey o'brien. Thank you for watching here on a Monday night. I'm David Muir. I hope to see you right back here tomorrow. Good night.
This transcript has been automatically generated and may not be 100% accurate.