IRVING, Texas — Finger-painting is fun for a lot of children, but for 6-year-old Caitlynne Truett, it marks a milestone as she battles cancer. On Wednesday with her hand painted purple, she put her handprint on a canvas at the Texas Center For Proton Therapy.

In October 2018, Caitlynne was diagnosed with Grade 4 Medulloblastoma. It is a common cancerous brain tumor in kids, but her case is rare. Caitlynne's cancer is aggressive, high risk, and the tumor is larger than a tennis ball.

"It's very hard to come to terms with," said Chris Truett, her dad. He said as parents, he and Jennifer Truett have not come to terms with the cancer, knowing the prognosis and the potential outcome. "It's devastating."

They quickly set up appointments, and her fight against cancer started. Caitlynne had her tumor removed at Cook Children's in Fort Worth, but a tiny particle embedded in her spine was not able to be resected.

Her parents then found a trial at St. Jude Children's Research Hospital, and got Caitlynne into the study. Because of the trial, she began heavy proton radiation therapy through the Texas Center for Proton Therapy.

Her parents knew this would be the maximum radiation Caitlynne could get in a lifetime, but the situation was grave. Their daughter wasn't moving or talking. Her parents say it was the chance to save her life.

Dr. Victor Mangona is a radiation oncologist. For Caitlynne, the radiation needed to enter her entire brain and spinal cord. He said proton therapy is safer and has less side effects. It targets a specific area and won't send radiation to other organs. 

After six weeks of proton therapy, Caitlynne started talking, feeding herself, and doing arts and crafts again. It is a leap from October, when she could barely move.

"She was getting better every time I saw her despite going through all this treatment," Dr. Mangona said. He said children are some of his most resilient patients.

Her parents are seeing the progress too. Caitlynne will soon begin chemotherapy for several months. They are holding hope that the tumor won't come back, and know this is the beginning of a long fight.

"Prayers, that's all we ask for," Caitlynn's father said.