Four years ago Ryan Sebring found out he had acute lymphatic leukemia, from the co-pilot of a helicopter at Centre Community Hospital.

"No one had told me yet why I was sick," Sebring said. "The co-pilot of the helicopter came in and told me and the whole room went silent."

Sebring was 20 years old and a student at Penn State, and a few days earlier he thought he had the flu.

"I was sick for six days," Sebring said. "I was really thirsty and had hot and cold flashes so I went to Ritenour."

University Health Services took blood from Sebring and sent him back to his dorm room. Hours later they called with news that his blood counts were "off the charts."

"They called me and told me that they were going to send my blood over to Centre Community for more testing," Sebring said. "I was thinking that I had pneumonia or meningitis."

Centre Community Hospital later contacted him and told him to come into the hospital. From there he was hooked up to a "bunch of machines," but he didn't know what was going on yet.

That's when the pilot came in.

"The day before I was worrying about if I could get the notes for the 8 a.m. class I had missed, or which dining hall was serving chicken that night," Sebring said. "When I initially heard that I had cancer I was numb. It didn't hit me yet."

He was admitted to Centre Community Hospital at 6 p.m. By midnight he was in Danville, where doctors and nurses worried that he might not make it to the next day.

"It really put my life into perspective when they started telling me that I should be thinking about where I wanted my stuff to go," Sebring said.

Within hours Sebring found himself in the company of friends and family.

"Before this I didn't really have a close relationship with my family," Sebring said. "I called them once or twice a month"

However, after being diagnosed, his relationship with his family changed.

"My dad and I used to never talk," Sebring said. "It was the normal growing pains stuff. The thing that impacted me the most was seeing him cry."

Andrew Kuklin was one of the friends who has been by his side through it all.

"I didn't know how to cope at first," Kuklin said. "So I got on the Internet and I found out all I could about his illness."

Doctors told Sebring that he needed a bone marrow transplant to save his life.

Ryan Sebring's sister, Kristen, may be the reason he is alive.

She was a perfect match.

"I was happy she was a match, but I was somewhat apprehensive to see her go though that," Sebring said. "The chances were so slim, but she was a match."

Kristen was barely 16 when she underwent the procedure that may have saved her brother's life.

"I was scared -- not just about the emotional part," Kristen said. "But I don't have a doubt in my mind that I would do it again for him in a second if they needed me."

Kristen underwent a procedure that increased her white blood cell count.

"They put a needle in one arm that put stuff in," Kristen said. "In the other arm I had another needle that took out my blood."

Kristen encourages people to become part of the National Marrow Registry.

"I can't understand why you wouldn't want to do it," Kristen said. "The fact that you can help save someone's life and help stop their suffering and their families suffering should be enough. It's worth it."

For a while Sebring endured chemotherapy and was taking 262 pills a day after the bone marrow transplant.

Years later Sebring is two years cancer "quiet."

"They don't call it remission until I go five years without a relapse," Sebring said.

He has had relapses before, but for now he is re-enrolled at Penn State working toward a degree in developmental biology.

The doctors told Sebring to wait before he went back to school, but he was sick of "sitting at home watching TV all day in the air conditioning."

When he first enrolled at Penn State he was majoring in premedicine. Now his focus has shifted. He doesn't want to treat people when they are suffering -- he wants to help catch illnesses before they happen.

Also, Sebring volunteers for the American Red Cross. He talks to groups about the importance of giving blood.

"I walk into the room and when I tell them that all the blood in my body is from donors it really gets their attention," Sebring said.

Before his illness Sebring never gave blood or volunteered for the Red Cross.

"I always thought that someone else could do it," Ryan said. "Now I know how important it really is."

Even though Sebring has been though more than most 24-year-olds, he still has what friends and family describe as a bright outlook on life.

"I believe that everyone has to go though one big thing in their life," Sebring said. "This was mine. I just got it out of the way earlier than everyone else."