April 1, 1997
Tulane researchers have developed a test documenting that leaking silicone breast implants produce an autoimmune response in the body that triggers severe neurological and muscular complications. Robert Garry, professor of microbiology and immunology and one of the study's principal researchers, says that the anti-polymer antibody test for the first time provides evidence that the symptoms experienced by women with silicone breast implants result from a real disease.
Previous studies have failed to produce such evidence. "It's a disease that hasn't been described," Garry says. "What we provided was the first objective evidence that it actually exists." Garry and researchers in his lab reported their findings from a blinded clinical trial of the test in the February issue of Lancet, a leading international medical journal. "The results of the study were better than we anticipated," Garry says. "Only 3 percent of the silicone breast recipients who were healthy tested positive. In the group with the most severe symptoms, 68 percent--or two-thirds--tested positive on the anti-polymer antibody test."
The test shows the presence of a unique antibody produced by the body to fight off the implant. The researchers propose that these antibodies react with joints, muscles and nerves throughout the body, resulting in disease. Garry's group studied 153 women--110 with silicone breast implants--at the Arizona Rheumatology Center in Phoenix. An undetermined number of women with silicone breast implants have reported such symptoms as tightening of the connective tissue surrounding the implant, muscle and joint pain and nervous system disorders.
More than a million women worldwide have received these types of implants. These symptoms are similar to autoimmune diseases such as lupus, where the immune system produces antibodies against its own cells and tissues. For a disease such as the one suffered by silicone breast implant recipients, where no set clinical judgment exists, a test in which nearly 70 percent of women with severe symptoms show a positive response is significant, Garry says.
"These are pretty complicated diseases," he says. "It's not like developing a test to show whether a virus is present or not. For assays like this that are used to diagnose autoimmune diseases, it's considered good if you could pick up half the patients in a particular group." Silicone is a synthetic polymer also found in medical devices such as hip replacements, pacemakers and certain dental appliances. The silicone gel found inside breast implants was initially developed to use as window caulking and insulation.
Unlike the shell of the breast implant, which is solid silicone rubber, the gel inside the implant has a looser molecular structure, Garry says. "The gel tends to leak or bleed out of the silicone rubber and it's a lot more mobile," he says. "In all cases, gel bleeds out of the implant, but the implants also rupture at a pretty alarming rate." Research on breast implant complications appeared in the March 6 New England Journal of Medicine soon after Lancet published Garry's study. In this study, Mayo Clinic researchers found that 24 percent of women with silicone breast implants had complications requiring additional surgery.
The most frequent complication reported was "capsular contraction," which results from the immune system walling off the implant and forming scar tissue around it. Scar tissue contracts over time, Garry says, leading to rupture. "The 10-year rupture rate is probably anywhere from 35 to 70 percent," he says. "Basically, the new study said that there was a 25-percent failure rate of silicone breast implants after five years, requiring additional surgery. If they were tires, you wouldn't want them put on your car with that kind of failure rate."
Garry has also applied the anti-polymer antibody test to the blood of hydrocephalus patients who have repeatedly rejected silicone shunts--tubing that draws excess fluid from the brain. He found that about five out of six of the patients who had recurrent problems of shunt rejection tested positive on the assays. "Obviously there are good medical implications for silicone devices, and I wouldn't even dismiss the cosmetic benefits," Garry says. "One of the reasons we developed this test is to be able to use it to develop safer biomaterials that could be used in making breast implants, shunts and other devices--something that wouldn't make one-fourth to one-half of [those recipients] sick."
Tulane has licensed the anti-polymer antibody test to Autoimmune Technologies, a local biomedical firm headed by Russell Wilson, a former faculty member in Tulane's pathology department. The test is in the early stages of approval by the Food and Drug Administration and is available to physicians for experimental use, Garry says. The next step for the researchers is to expand their study to more patients in different areas of the country. Garry stresses that the question of silicone breast implant safety needs more scientific inquiry. "What's been lacking in this area is good science," he says. "That's the most important contribution we can make."
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