Ten-year-old Gavin Pierson competes at state-level karate championships, but getting good at the sport required more practice than that of the ordinary athlete. About four years ago, a tumor comprised of human skin, hair, bone and cartilage was fast-growing inside the Ramsey, Minnesota, youth’s brain. When five craniotomies failed to permanently remove the mass, surgeons didn’t know if he would live— much less go on to perform a highly technical sport that requires physical strength and coordination.

But after undergoing multiple rounds of laser ablation therapy, an emerging surgical technique for removing pediatric brain tumors that he finished in early June, Gavin is like a regular kid again. He has achieved a purple belt in the martial art, is riding his bike for the first time in years, and, after re-learning to read, has returned to grade level.

“This is the first time in four years that we’re in remission,” Nicole Pierson, Gavin’s mother, told FoxNews.com. “The laser changed Gavin’s life.”

“Something extra” in Gavin’s brain

Growing up, Gavin had good balance and flexibility, so his parents signed him up for gymnastics when he was 3, a sport he continued to practice until he was 6. Common early symptoms of a brain tumor include poor balance and dizziness, but as Gavin continued to excel on the bars and rings, he didn’t suffer from either when his tumor presented in April 2012.

It was itchy eyes, which at one point he couldn’t open, that led Nicole to seek advice from a relative who is a pediatrician. She noticed Gavin’s eyes weren’t tracking together, and she urged Nicole to take him to the emergency room at Children's Hospitals and Clinics of Minnesota. There, doctors conducted the CT scan that would reveal a mass about the size of a golf ball growing in Gavin’s brain. After a blood test, Gavin was diagnosed with a teratoma, which represents less than half of 1 percent of pediatric brain tumors, and hydrocephalus, or a buildup of fluid in the brain.

“[Gavin] is such a funny kid,” Nicole recalled. “The whole time he was in kindergarten, he would say, ‘I can feel my brain getting bigger because I am smart!’ He was probably feeling some pressure.”

It was then that 34-year-old Nicole, a middle school math teacher, and her husband, 37-year-old Steve Pierson, a carpenter, had to gently and tactfully break the news to Gavin.

“’Buddy, we’re really sorry to tell you this,’” Nicole recounted, holding back tears, “but there’s something extra in your brain that shouldn’t be there.”

Gavin nicknamed his tumor “Joe Bully” and set off on a slew of surgeries and treatments. None cured him of the tumor that, while not cancerous, threatened to pose neurological problems or worse.

“Unfortunately, with children it’s possible, as well as [with] adults, that you can have poor neurologic symptoms, disability or death with benign lesions if they can’t be surgically removed,” Gavin’s surgeon Dr. Joseph Petronio, director of pediatric neurosurgery and co-director of neuroscience at Children’s Minnesota, told FoxNews.com.

First, due to the teratoma’s depth in Gavin’s brain, doctors recommended chemotherapy, but chemo didn’t help. Gavin’s tumor grew to the size of a peach.

Some of the operations also involved draining the excess fluid from his brain, and others, like the craniotomies, aimed to more directly extract the tumor located adjacent to the critical brain stem, with as little consequence as possible, by operating through a window in the skull.

“Each was followed by recovery, rehabilitation and therapy, which he did nicely with. But by the time he bounced back from [each], the tumor had started to regrow,” Petronio said.

Nicole, who had also been caring for her son Gage and daughter Grace, now 7 and 11 respectively, said every day was a struggle.

“Fear was creeping up all the time— fear of whether or not he was going to live or make it, and that fear could swallow you,” she said. “But I purposefully focused on Gavin. He was never scared, and he would tell us, ‘Mom and Dad, we’re gonna be OK. You have to believe me; you have to believe me.’”

“He had faith. He believed,” Nicole added. “If you look at Gavin on paper, it doesn’t look good, but of course when you’re just with Gavin, you know he’s gonna make it.”

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In early January 2013, following Gavin’s fourth craniotomy, the family had to make a life-changing choice.

“I will never forget having to sit in Dr. Petronio’s office and him telling us Gavin had a few months to live if we quit, and if we continued surgery, [its risks] would outweigh any benefits,” she said. “He asked, ‘Do we want to keep going?’ and I could tell it was his medical responsibility to ask us that question— it was a very fair question, but you don’t want to hear it. But I could also tell he didn’t want to give up.”

Hope in laser therapy

As the Piersons and Petronio scrambled to find a solution for Gavin, they moved forward with a fifth and final craniotomy because the tumor was immediately threatening his life. After taking what Nicole described as a series of “two steps forward” then “three steps back” events, they found hope.

In February, the Piersons obtained palbociclib, an advanced breast cancer drug that, through independent research online, Nicole found showed promising results in adult teratoma patients. Gavin ended up testing positive for the appropriate genetic markers, and Pfizer granted the family compassionate use of the drug. Although palbociclib stabilized his tumor, the drug did not shrink it.

Meanwhile, Petronio had his sights set on a treatment he thought could do just that: a laser that, in multiple rounds, was targeting and melting persistent, hard-to-reach brain tumors and epilepsy hotspots in adult patients.

Laser ablation therapy belongs to an emerging class of minimally invasive neurosurgeries, and the Food and Drug Administration approved it for the aforementioned uses in 2009. Petronio said it involves temporarily implanting a device and a laser fiber through about a 1 millimeter hole.

“We have all kinds of abilities to deliver a fiber to a target— the tumor, or in other cases, a seizure-generated target— within a millimeter of accuracy,” Petronio said. “So, we’ve been able to access critical areas of the brain and plan our approaches carefully.”

Using the laser on Gavin required approval from the hospital’s regulatory board, but Patronio also needed to obtain the $400,000 device. The Piersons wrote letters about Gavin’s journey to potential donors and garnered support from supporters such as the ice hockey team Minnesota Wild, which donated about $75,000 toward the laser, Nicole said.

“That you would go to the ends of the world for your child— that is so tangible when you know that they need a cure,” Nicole said.

When the board granted its approval, and Children’s Minnesota and the Piersons fundraised enough to purchase the laser, Petronio set off to remove Gavin’s tumor.

Using MRI imaging, he and his team continuously measured the temperature of the laser energy against the anatomical structures of Gavin’s brain, thereby surgically removing the tumor, called ablation, in real time. The technology calculates the amount of eradicated tissue based on time and temperature.

“To destroy tissues can be a pretty long operation between planning and length of time, but the bottom line is it’s still considered a minimally invasive surgery, so kids are typically sitting up and eating dinner that night.”

Petronio has conducted 22 surgeries with the laser and MRI technology, and three patients have had teratomas, including Gavin, who underwent six rounds of ablation every six months, starting in October 2013. On June 2, 2016, Gavin underwent his last ablation.

That month, Petronio presented a study on the utility of the laser ablation technique in the intraoperative MRI suite at the International Society of Pediatric Neuro-Oncology (ISPNO) conference in Liverpool, England. The study has been submitted for publication in the Journal of Neurosurgery – Pediatrics.

Petronio is also in the midst of conducting a study that aims to analyze the efficacy of the technology on pediatric tumors of all types.

“I think that it has shown promise for not only rare tumors like Gavin’s, which have been previously very difficult to treat, but even for more common pediatric brain tumors that have involved the optic pathway and the hypothalamus, which can notoriously be large and hard to treat, and for small lesions that have recurred after a craniotomy.”

“I hope that, based on our study that’s currently underway, that this form of treatment will gain increasing acceptance,” he added.

Gavin is temporarily taking a blood thinner due to a previous blood clot complication, but whenever Nicole takes him to the pediatrician, they think he’s an ordinary 10-year-old boy. She still worries if he says he has a headache, but whenever that happens, she doesn’t feel a wave of anxiety rush over her or think she must rush him to the ER.

For the second summer in a row, the Piersons are going on a family camping trip on the north shore of Minnesota.

“We can plan for life and not feel afraid,” Nicole said. “Before, I was almost sad to plan for the future because we didn’t know if Gavin would be in it. And now, we have this really good thing going where we can say Gavin will be there.”

Nicole’s book on Gavin’s medical journey, “Be Strong and Brave: How a Child’s Faith Saved His Life,” will be available on Amazon and Amazon Kindle on Thursday, Aug. 18.