NeuroNow - Treating Chordomas
Date: November 30, 2009
Some patients who have the rare bone cancer known as chordoma undergo multiple operations. Hopkins neurosurgeon Ziya Gokaslan says he’s cared for patients who have had eight, 10 or even 15 procedures to remove the tumor—one that occurs anywhere along the spine from the base of the skull to the tailbone. But Gokaslan and fellow neurosurgeon Jean-Paul Wolinsky believe that many of those surgeries could be avoided.
Because chordoma is so infrequent — only one out of one million people develop the disease each year — most physicians never see a patient with the tumor, says Gokaslan. Even most neurosurgeons will encounter perhaps only one case in their career. As a result, he says, “most doctors may not think to diagnose the tumor, and many don’t know the behavior of the disease.”
One misconception, he says, is that chordomas are benign. Although they tend to grow slowly, they are, in fact, malignant tumors and can metastasize.
Another misunderstanding has to do with the surgical technique used to remove a chordoma, which can vary in size from the dimensions of a marble to that of a basketball. One approach, intralesional resection, involves cutting into the tumor and removing it in a piecemeal fashion. Using this technique, says Wolinsky, a surgeon might avoid the need to remove vertebrae, nerves or other tissues to access the tumor. However, while the intralesional resection might be a conservative approach, it increases the risk of recurrence. That’s because pieces of tumor are spilled during the resection. Even microscopic bits of tumor remaining in the body can reseed along the spine or elsewhere and begin to grow. “This approach almost guarantees that the tumor will come back,” says Wolinsky. And when it does, patients return for another surgery.
A better approach, according to Wolinsky and Gokaslan, is to remove the tumor in one integral piece, a surgical approach called an en bloc resection. The procedure may require surgeons to make several incisions to access the tumor, and to sacrifice vertebrae and nerves and muscles infiltrated by the tumor. Often, a second operation is required to reconstruct the patient’s spine. “Chordoma surgery is probably at the top of difficulty on the list of neurosurgical operations,” notes Wolinsky.
However, en bloc resection offers patients a better outcome than the intralesional resection, he says. “Many of our patients have a fairly normal life following surgery. They go back to work and resume other activities.” He and his colleagues perform two to three chordoma surgeries each month.
Still, some chordoma patients are not candidates for an en bloc resection. In particular, they include patients whose tumors lie in the delicate region at the base of the skull. For those and others, Gokaslan hopes that research under way in his laboratory will help improve those odds. He is especially excited about new strategies for growing model chordoma cells that he and pediatric oncologist David Loeb are developing.
Gokaslan and other scientists had been trying for years to get the tumors to thrive in lab dishes or animals. This year, Gokaslan and Loeb succeeded in growing a certain type of chordoma cell using a strain of mouse that lacks an immune system. Although it is still a work in progress, an animal model will let them test various chemotherapy drugs and radiation techniques to stop or slow the growth of chordomas. Such interventions, used either with or without surgery, would offer doctors more variety in treating patients with chordoma.
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