By Stephanie Stahl

PHILADELPHIA (CBS) — John McCormick and Ryan Rothman, second-year medical students at Drexel University, are friends and share an unusual medical twist.

McCormick was a recipient. Rothman was a donor.

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Every three minutes someone is diagnosed with a blood cancer, like leukemia and any will need bone marrow transplants to survive.

An organization called “Be The Match” supports patients and has a registry of 19 million potential donors.

“It means a lot to me to have a friend who gave somebody else a second chance because I know how important that is to me,” McCormick said.

McCormick was diagnosed with leukemia when he was a 21. A bone marrow match couldn’t be found because he’s mixed race, so he had a stem cell transplant using blood from umbilical cords.

“When I was 21, I didn’t know much about what compassion was, or what giving back was,” McCormick said.

“I was just enjoying myself in college and when I got that, I really realized when you fall down, you really need some help getting back up. And that was the first time I really realized that compassion exists in this world and we need each other to survive.”

McCormick’s story inspired Rothman to join the “Be The Match” registry, with a simple mouth swab.

Turns out his bone marrow was a match for an unidentified woman with leukemia.

“It’s just a surreal feeling knowing that with very minimal effort on my part I was able to save someones life who, like john said, was on the brink of death,” Rothman said.

He says the donation of blood was simple and painless.

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“It meant the world for me that he was willing to donate because I know as a recipient how important it is that people donate and give somebody a second chance because I wouldn’t really be here if I didn’t have a second chance from a donor,” McCormick said.

Aiming to help more people like McCormick and Rothman, “Be The Match” will have it’s annual walk run this Saturday.