– With radio interviews going on all around him, Casey O’Brien unbuttoned his crisp white shirt right in the middle of a hotel conference room, tugging it aside to reveal a raised, red line.

The scar is a souvenir from a port in his chest that delivered chemotherapy, something O’Brien endured as recently as last season. The Gophers redshirt sophomore has beaten cancer four times since he was 13, persevering to become a college athlete and inspire other teenage cancer patients.

On Friday his story impacted an entire athletic conference, as he spoke to the Big Ten’s Kickoff Luncheon about his experience with osteosarcoma, a rare bone cancer. His speech elicited tears, handshakes from several conference coaches and a good minute-long standing ovation from a packed ballroom.

“When I look back at it, football has been probably the main thing that has been consistent through it all,” O’Brien said Thursday back in that conference room. “Whether I’m playing or just being around the game, it’s something that’s always been in my life, and it’s somewhere where I can always go to get away from everything. And especially when I’m in the locker room with my teammates, I just feel like another kid. So no matter what’s going on, that’s probably my favorite place to be.”

Football has been more than just a relief for O’Brien. It was literally a lifesaver. As a freshman quarterback at Cretin-Derham Hall, left knee pain caused him to seek help from several doctors. The Gophers became a critical part of his journey soon after, with their medical staff diagnosing him, thanks to his dad, Dan O’Brien, working in the football department at the time.

Dan O’Brien and wife Chris drove the six hours to watch their son’s speech, with Chris O’Brien saying she started crying as he walked up to the podium.

“He is a special kid, and we know the way he’s handled the whole situation that there’s something different about him,” Dan O’Brien said. “But to be on a stage like this and have an opportunity to give his message and how he wants to help other people. He said to me before he went up, he said, ‘Dad, this is like a dream come true.’ ”

Since Casey O’Brien’s original diagnosis and three recurring bouts with spots in his lungs, he has endured a full knee replacement, months upon months of chemo, three lung surgeries and a specially FDA-approved immunotherapy treatment.

He wasn’t even supposed to play football again after the knee operation, as a hit would be catastrophic with all the metal in his leg. But Chris O’Brien said her son has always had a “fear second, go first” attitude, so of course he found a way around that.

The lifelong quarterback up to that point switched to placekick holder, a position with much less risk for contact. Even bald and down to 130 pounds, he held for extra points between chemo treatments in high school. For college, Gophers coach P.J. Fleck was the only coach to call him with a walk-on opportunity, and the Gophers were the only program to medically clear O’Brien to play.

But O’Brien isn’t on the team just to be a mascot. He wants to start.

“I took chemo pills before every spring practice at my first spring ball at Minnesota. I did not miss a practice,” O’Brien said in his speech. “I spent all last season wearing a specially made shirt with a pad sewn into it to protect the port in my chest while I was still getting treatment [every Wednesday after practice]. I did not miss a practice.”

O’Brien has now been cancer-free for almost a year and a half, relying on scans every three months and a low sugar, high chicken-and-broccoli diet to maintain his health.

And while it’s of course scary to never know when or whether the cancer is coming back, he will always have the game he loves to carry him through the unknowns.

“I would have been lost,” O’Brien said, “without football.”