10-Year-Old Becomes Lifesaving Hero by Donating Stem Cells to His Dad

When Dr. Nick Mondek discovered his cancer had returned this spring, he never imagined that his 10-year-old son, Stephen, would become the hero who saved his life.

“Stephen proves that real-life heroes come in all shapes, sizes, and ages,” Mondek told ABC News. “Sometimes, they’re right in front of us—and one act of bravery can completely change your life.”

Mondek, a Los Angeles anesthesiologist and father of two, had previously battled acute myeloid leukemia—a cancer of the blood cells—undergoing chemotherapy and a stem cell transplant. In 2022, his older brother Dave had donated stem cells to help him recover.

This time, however, Mondek faced a desperate situation. Despite reaching out to extended family and searching the National Bone Marrow Registry, no suitable donors were available.

“It was a dismal prognosis. I needed a donor immediately, and there was no one available,” he said. According to the National Cancer Institute, acute myeloid leukemia progresses rapidly, making timely treatment essential. After chemotherapy and radiation, another stem cell transplant became Mondek’s last hope.

Doctors at Cedars-Sinai successfully collected stem cells from Stephen, and on July 30, Mondek received his second transplant.

“He didn’t have to put on a cape or leap buildings in a single bound,” Mondek said proudly. “Instead, he put on a hospital gown and gave me hope. I’m not just honored to call this boy my son—I’m honored to call him my hero.”

Stephen, meanwhile, said he felt supported by his friends. “It feels good to do that, because all my friends are proud of me,” he told ABC Los Angeles station KABC.

Both father and son are now home. Mondek shared that Stephen returned to baseball practice just days after the procedure.

While Mondek faces a long road to recovery, his outlook is promising. “They did a blood test last week to check for any leukemia DNA in my blood, and they couldn’t find any. As of now, I’m still in remission—there’s no sign of cancer.”