Millions of radioactive beads are delivered to the blood vessels that feed the tumors
See our SIR-Spheres Web site.
The University of Maryland Greenebaum Cancer Center is now treating patients who have inoperable liver cancer with a state-of-the-art internal radiation therapy called SIR-Spheres that uses millions of microscopic radioactive beads to help destroy tumors from the inside out.
The U.S. Food and Drug Administration has approved the therapy for patients with primary colorectal cancer that has spread to the liver. More than 40 percent of the estimated 147,000 people in the United States diagnosed with colon cancer each year develop liver metastases that prove to be fatal.
SIR-Spheres, the next generation of radioactive “microspheres” developed to treat liver cancer, are manufactured in Australia by Sirtex Medical, Inc. The company ships them more than 10,000 miles from Sydney to Baltimore in a tiny vial shielded by a lead container. Each vial contains 40 million to 80 million microspheres, which remain potent for only 2½ days.
“SIR-Spheres deliver up to 40 times more radiation directly to tumors than would be possible using conventional external radiation,” says William F. Regine, M.D., chief of radiation oncology at the University of Maryland Medical Center and professor and chairman of the Department of Radiation Oncology at the University of Maryland School of Medicine.
David A.Van Echo, M.D., a medical oncologist at the University of Maryland Greenebaum Cancer Center and professor of medicine and radiation oncology at the University of Maryland School of Medicine, says, “SIR-Spheres selectively target tumors in the liver, regardless of their size or location, with a high dose of radiation, sparing the surrounding healthy tissue. The treatment is an outpatient procedure, and patients can go home the same day.
“The treatment has been shown to shrink liver tumors, increase life expectancy and improve the quality of patients’ lives,” Dr. Van Echo says, adding that there is no risk to other family members from the radiation. Possible side effects of the treatment include nausea, vomiting, mild fever, abdominal pain and fatigue.
SIR-Spheres are administered through a tiny catheter placed in the femoral artery in the upper thigh and threaded into the hepatic artery, a major blood vessel in the liver. The polymer beads -- one-third the diameter of a human hair and imbedded with a radioactive element, yttrium-90 -- lodge in the small blood vessels that feed the tumor.
“We use sophisticated X-ray imaging to help guide the catheter into the hepatic artery and implant the SIR-Spheres,” says Patrick C. Malloy, M.D., director of vascular/interventional radiology at the University of Maryland Medical Center and associate professor of diagnostic radiology at the University of Maryland School of Medicine. “The procedure generally takes less than an hour, and patients tolerate it extremely well. Within two to six hours, they’re ready to go home.”
The beads remain in the liver and lose their radiation within two weeks. Patients generally receive two treatments, one to each lobe of the liver, four weeks apart.
Dr. Regine says, “We believe that this is a safe and very promising treatment option for some patients with advanced colorectal cancer that has spread to the liver. It is only one of a wide range of targeted therapies that the University of Maryland Greenebaum Cancer Center offers to patients with liver cancer.”
Other treatment options include using radio waves to destroy tumors with heat (radiofrequency ablative therapy), injecting tumors with chemotherapy drugs and tiny particles that block the blood vessels (chemoembolization) and very precisely targeting tumors with high doses of radiation without damaging surrounding tissue (extracranial radiosurgery). Traditional surgical, chemotherapy and external radiation approaches are used as well.
Physicians at the University of Maryland Greenebaum Cancer Center have extensive experience using radioactive microscopic beads to treat inoperable liver cancer. The cancer center was the first institution in the United States to successfully perform another procedure using microscopic glass beads called TheraSphere as an outpatient therapy in 2000.
The SIR-Spheres treatment was first used in Australia, New Zealand and Asia before being introduced in the United States. In 2002, the Food and Drug Administration approved the targeted therapy for treatment of colon cancer that has spread to the liver.
Patients are evaluated by a team of physicians, which includes Dr. Van Echo, Dr. Malloy and Pradip P. Amin, M.D., a radiation oncologist at the medical center and assistant professor of radiation oncology and surgery at the University of Maryland School of Medicine.
The University of Maryland Greenebaum Cancer Center, which has a multidisciplinary approach, treats 15,000 patients a year and is a nationally recognized leader in cancer treatment and research. It has specialized programs for lung, prostate, breast, blood and brain cancers. For more information about SIR-Spheres, go to www.umgcc.org/sir-spheres/index.htm/.