Pennsylvania Teen Marks End of Cancer Treatment With 'Rocky' Run

— -- A 13-year-old Pennsylvania boy who underwent nearly 18 months of cancer treatment after doctors found a football-sized tumor in his stomach marked the end of his treatment Sunday by taking a page out of the hit “Rocky” movies.

Sean Bartolucci, of Camp Hill, Pennsylvania, ran up the stairs of the Philadelphia Museum of Art two at a time with about 30 friends and family wearing "Sean's a Fighter" T-shirts behind him. The teenager celebrated at the top by raising his arms above his head and letting out a “woo-hoo."

“He did it. He conquered it,” Sean's mom, Michele Bartolucci, told ABC News. “What a great way for him to celebrate, to know that we all are behind him and will continue to be.”

Bartolucci says her son’s battle against neuroblastoma began one night in February 2014 when he complained of a sore back. When Sean collapsed the next morning before school, his parents, Michele and husband Chris, took their son to the emergency room.

“Eight hours later they discovered he had a tumor the size of a football in his stomach,” she said.

Sean was treated mainly by doctors at Children’s Hospital of Philadelphia, a nearly two-hour drive from the family’s home. He underwent more than five rounds of chemotherapy, a stem cell transplant and a radiation treatment that required him to be in an isolated room for six days.

Along the way, says Bartolucci, Sean met countless doctors and nurses who saved his life, including one doctor whom Bartolucci recalls Sean nicknamed, “the Derek Jeter of surgeons.”

“He had bad days and he would cry and scream and then a couple of hours later he would say, ‘I’m so sorry mom and daddy,’ and we’d say, ‘It’s OK. It’s fine,’” Bartolucci said. “Maybe he did that five times out of nearly 18 months. He is amazing.”

Children’s Hospital of Philadelphia did not respond to an ABC News request for comment.

Sean came up with the idea to run the museum’s steps, a la Rocky Balboa, on his own.

"We were in Philadelphia when I got diagnosed," Sean told ABC station WPVI-TV in Philadelphia. "So this was one of the first things that came to mind.

"It just further proves that I have such an amazing community, such an amazing family, and so many amazing friends to lean back on if I ever need to," Sean said off all the family and friends running behind him.

Sean finished his treatments June 6 but took from then until Sunday to build up his strength. He will spend the rest of the summer preparing to get back to being an everyday teenager and enter eighth grade in the fall.

“Through all of his chemotherapy and the radiation, he did online schooling to complete seventh grade and move onto eighth grade,” Bartolucci said. “That’s how much of a trooper he is.”