HEALTH

St. Jude proton therapy hits milestone, treating 150 kids

Tom Charlier
USA TODAY NETWORK – Tennessee
January 18, 2017 - Radiation therapists George Kozan, left, and Andy Saunders prepare their 15-year-old patient, Megan Vess, for a treatment in the Proton Therapy Center at the St. Jude Children's Research Hospital on Wednesday.

Megan Vess, a pony-tailed 15 year old who would rather be hunting in the mountains of her native North Carolina, instead finds herself on a January afternoon tracing the familiar route leading to the St. Jude Red Frog Events Proton Therapy Center, where physicians are about to shoot streams of charged particles into her brain to fight an aggressive tumor.

"I'm tired," she tells radiation therapist Andrew Saunders as she enters the facility. "My bed is going to feel so good."

Her bed is actually a robotic couch that rises, drops, swivels, pitches and rolls to exact, computer-directed increments. Megan gets strapped to it, with a specially fitted plastic mask placed over her face to further restrict movement.

Then, with music she's selected playing in the background, Megan relaxes as machines seemingly out of a science fiction movie spring to life.

A cone-beam CT scanner drops over and around her to take images used to precisely target the area of her brain to be treated. A gantry then swivels to different angles to zap the tumor with a beam of hydrogen protons that have been shot along a 200-foot track and accelerated by powerful magnets to 60 percent of the speed of light.

The 10th-grader from Marion, North Carolina, is one of the latest patients to benefit from the world's first proton-therapy facility dedicated solely to treating children. Since receiving its first patient in November 2015, the $60 million facility in St. Jude Children’s Research Hospital has treated some 150 kids with tumors primarily of the brain, soft tissue and bone.

Therapy employing protons, the positively charged particles in atoms, is considered a major advance from traditional radiation treatment using X-rays.

January 18, 2017 - Radiation therapist George Kozan looks at brain scans of 15-year-old patient, Megan Vess, during her treatment in the Proton Therapy Center at the St. Jude Children's Research Hospital on Wednesday.

Because the electromagnetic fields of X-rays can pass through most objects, they damage tissue other than the tumor, including the still-developing brains and organs of children. As a result, doctors often have to reduce the dose delivered to the tumor, making the radiation less effective.

Proton beams, by contrast, stop after releasing their energy in the tumor. They also can be more precisely controlled and are accurate to within one half-millimeter of their target, allowing doctors to hit the tumor with higher doses.

In a room outside the chamber where Megan is being treated, Saunders and fellow radiation therapist George Kozan watch images on screens as they guide the proton beam on back-and-forth sweeps at thousands of prescribed points at various depths in the tumor.

“Everything we do in the proton therapy center is image-guided,” Saunders said. “We’re able to spare all this healthy tissue around (the tumor).”

The precision targeting means that unlike traditional radiation, proton therapy doesn’t cause cognitive damage or trigger vomiting and nausea – medication for which is expensive.

“One of the most striking things we’ve noticed is a reduction in acute side effects,” said Dr. Thomas Merchant, chairman of the department of radiation oncology at St. Jude.

January 18, 2017 - 15-year-old patient Megan Vess undergoes a treatment in the Proton Therapy Center at the St. Jude Children's Research Hospital on Wednesday.

Some of the older patients who have completed proton therapy say there’s no discomfort.

“That was the easiest treatment of all time,” said Ricky Terry, now 23, of Memphis, who last year underwent therapy for a type of brain tumor called a medulloblastoma. “You lay down, put a mask on your face and fall asleep.”

Although it’s too early to determine whether or how much the proton therapy is increasing survival rates, Merchant agrees that, theoretically, “if we can safely increase the radiation dose, we could cure more of the more difficult tumors.”

That’s particularly important because although St. Jude has achieved dramatic success in battling childhood leukemia and some other cancers, its progress against solid tumors has somewhat plateaued.

Megan’s case is particularly difficult. She had been treated at St. Jude earlier for acute lymphoblastic leukemia. Although the treatment was successful, doctors later discovered she had a mutation in a gene that facilitates the repair of DNA in damaged cells.

January 18, 2017 - Radiation therapists George Kozan, back, and Andy Saunders (not pictured) prepare their 15-year-old patient, Megan Vess, for a treatment in the Proton Therapy Center at the St. Jude Children's Research Hospital on Wednesday.

“She got two bad copies – one from me, one from her dad,” said Megan’s mom, Amber Vess.

The gene mutation renders Megan predisposed to several types of cancer. And in December she was diagnosed with glioblastoma, a type of brain tumor that’s tough to treat in part because of its tentacle-like extensions.

“Generally, these tumors are aggressive and do come back even after radiation and chemotherapy,” said Dr. Christopher Tinkle, who is a member of St. Jude’s department of radiation oncology and is treating Megan.

With the proton therapy, however, doctors hope to sufficiently shrink the tumor and control it long enough for Megan to benefit from new types of immunotherapy that have shown promise in treating glioblastomas.

Tinkle calls proton therapy an “exciting” advance.

“There’s obviously much to be learned from this new technology,” he said.