Finding new ways to kill what surgery can’t.
Four years ago, at age 5, Daniel Suero walked into a hospital for surgery to remove a tumor in his spinal cord – but he didn’t walk out. The Illinois child left paralyzed, in the wheelchair he would use for the next six months before moving to a walker and crutches.
“It was absolutely horrible, a nightmare,” says his mother, Helen Suero.Yet this unfortunate outcome is not so uncommon for the type of tumor – intramedullary – wrapped in and around Daniel’s spinal cord. Although these lesions tend to be benign, low-grade and slow-growing tumors, they infiltrate and impinge on the fragile spinal cord in inextricable ways.
Even the most experienced neurosurgeons are able to remove only 90 to 95 percent of these rare tumors, leaving patients vulnerable to neurologic, motor and sensory problems. Indeed, there’s a 30 percent chance of patients coming out worse than they went in. But left untreated, they may face paralysis and even death.
“These tumors are not that common but they’re devastating,” says pediatric neurosurgeon George Jallo, noting that the 10-year survival for low-grade intramedullary spinal tumors is as low as 40 percent. “If the tumor is high in the spinal cord, it will likely affect breathing and they may die.”
Jallo should know. Since training in 1991, when he saw too many children suffering from this disease, he’s made treating these patients the centerpiece of his career. And at the heart of his work is developing methods, like slowly releasing chemotherapy agents directly into the tumor, to attack the 5 percent to 10 percent of inoperable remaining tumor. But the battle is not without challenges. While these drug therapies work effectively and safely against brain tumors, against spinal tumors their permeability is limited and they tend to have systemic side effects on the central nervous system.
The good news is that Jallo has developed animal models to test new drugs and safer delivery methods. A rabbit model provided a suitable means to test dosages and toxicity (J. Neurosurg: Spine, August 2005), and a newly developed mouse model, in which Jallo uses malignant cell lines to better mimic the behavior of spinal cord tumors, offers new opportunities for testing novel therapies (Neurosurgery 659:193:200, 2006).
“The animal models show some of these treatments are efficacious,” Jallo says. “We haven’t cured them yet, but we’ve prolonged the survival curve.”
In his studies, Jallo is also attempting to develop a radiation sensitizer to inject into spinal tumors so that radiation therapy — the mainstay therapy for residual disease — can have a more-potent effect. Radiation works against these tumors, Jallo explains, but the amount of radiation needed harms healthy tissue, too.
“We’re hoping to make a sensitizer so we can decrease the dose of radiation to that area,” Jallo says. “We’re not going to get rid of the need for surgery, but we’re going to make surgery safer because we won’t have to take all of it out. Right now we have no room for margins.”
Because of the high recurrence rate of intramedullary spinal tumors, Jallo often finds himself operating on patients like Daniel who have already had surgery elsewhere. After surgery with Jallo, Daniel was able to move his toes after doctors tickled his feet. Moreover, he was able to lift his leg higher than he had in the previous four years. Today he’s a third-grader on his school swim team.