Gophers' Casey O'Brien, 5-time cancer survivor, retires from football
He has dealt with multiple bouts with a form of bone cancer since he was 13.
Gophers placeholder Casey O’Brien beats cancer for fifth time
O’Brien shared the news on his final day of chemotherapy.
Watch: 4-time cancer survivor Casey O'Brien makes Gophers debut
It was an emotional moment for all involved.