DHMC is only center in New England to do new liver cancer therapy
Diamonds may be a girl's best friend, but glass beads are proving to be some liver cancer patients' best ally. Millions of tiny beads, called microspheres, are part of a new treatment at DHMC for patients with unresectable, or inoperable, hepatocellular carcinoma (HCC). This form of cancer is characterized by tumors that cannot be surgically removed and that originate and stay in the liver. Patients with HCC typically have a life expectancy after diagnosis ranging from 4 to 18 months.
Dartmouth's Norris Cotton Cancer Center is the only place in New England that offers the treatment, known as Therasphere. Bassem Zaki, M.D., a radiation oncologist, says that DHMC started doing the procedure in late 2004 and has treated eight patients so far.
Beads: The glass beads used in Therasphere are embedded with the radioactive isotope yttrium- 90 (Y-90). The microspheres, in a saline solution, are inserted through a catheter into the femoral artery in the patient's thigh. From there, they travel into the hepatic artery and on into the liver. They then become trapped inside the tumor because the spheres are slightly larger than the surrounding microvessels. The Y-90 targets the tumor quickly and precisely. It affects only tissues within a range of less than a centimeter but delivers a dose five times higher than external beam radiation. The Y-90 decays over 2.7 days into non-radioactive zirconium, and the tiny bits of by-then inert glass stay in the liver, causing no problems.
Patients who have had Therasphere have suffered minimal side effects, and their tumors have decreased substantially in size. Zaki says it is a very good alternative to the traditional treatment, transarterial chemoembolization (TACE). TACE combines anti-cancer drug therapy to shrink the tumor with embolizing, or blocking, the hepatic artery that feeds the tumor. However, TACE requires a hospital stay of two to five days and can cause more damage to surrounding tissue than Therasphere. In addition, most patients suffer post-embolization syndrome—a reaction to blood being cut off to a solid organ—as well as nausea, abdominal pain, and low-grade fever.
Organ: Furthermore, TACE is not an option for some patients if their liver is relying solely on the hepatic artery for its blood supply, because the organ's other blood supply, the portal vein to the liver, has become clotted due to the disease. TACE would require blocking such patients' only functioning blood supply, which would damage the liver. Therasphere avoids that problem because it doesn't involve blocking the artery.
Therasphere is done on an outpatient basis, and the procedure takes just one hour, with a three- to four-hour recovery time. Side effects are usually limited to a couple of weeks of generalized fatigue, mild nausea, and a temporary elevation of the liver enzymes. "That's about it," says Andrew Forauer, M.D., an interventional radiologist who assists with the treatments. The only complications, he explains, arise if some of the spheres migrate into the stomach or the small bowel, where they can cause ulcers. Such complications are not common, though, adds Forauer.
Side effects: "It looks like the Therasphere has a lot less side effects than the chemoembolization . . . and that's partly because it localizes mainly where the tumor is," says Zaki.
"The reason that we're able to [offer this treatment] is simply because of the culture here," explains David Gladstone, Sc.D., a physicist who sets up the delivery device and does the radioactivity measurements. At DHMC, he says, "disparate groups can easily interact with one another and they have a highly collaborative approach in order to deliver firstrate care to the patient."
The team has not yet fully analyzed its results with the new treatment. However, a study published in the Journal of Vascular Interventional Radiology, about the use of Therasphere at other centers in the U.S. and Canada, showed that a low-risk group of 88 patients had a median survival rate of 466 days—at the high end of the usual survival range; minimal side effects; and no confirmed cases of radiationinduced liver disease.
Matthew C. Wiencke
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