Researchers in Austria have identified proteins that accumulate on the surface of silicone breast implants, which they say could be the cause of immune reactions in women who have them.
The FDA ordered silicone-gel filled breast implants off the market in 1992 after a flurry of complaints that they caused autoimmune illnesses and even cancer.
Thousands of women sued implant maker Dow Corning, and settlements forced the company into bankruptcy.
But on Nov. 17, the FDA approved the request of two other companies to begin marketing the implants, stating that research shows "no convincing evidence" breast implants cause either connective tissue autoimmune disease or cancer.
"The extensive body of scientific evidence provides reasonable assurance of the benefits and risks of these devices," FDA director for devices and radiological health Daniel Schultz, MD, said in a news release at the time.
Findings Raise New Questions
In the newly-reported Austrian study, researchers showed that key proteins accumulate on the surface of silicone breast implants long after the implants are placed in the body. They were able to do this using a relatively new, targeted research method known as proteomics.
These proteins provide a link between silicone implants and autoimmune disease, says lead researcher Aleksandar Backovic, of Austria's Innsbruck Medical University.
"We believe this is at least one of the causes of the immune system problems that have been attributed to silicone implants," Backovic tells WebMD.
Further study revealed the reaction is likely to occur many years, and even decades, after implantation, rather than weeks or months later. Backovic says this could explain why earlier research failed to identify the protein adherence.
The study appears in the December issue of the American Chemical Society publication, Journal of Proteome Research.
Implants Extensively Studied
In allowing the return of silicone-filled breast implants to the U.S. market, the FDA noted they were among "the most extensively studied medical devices."
But Renee Carter, of the National Research Center for Women and Families, tells WebMD that the relatively new research methods used in the Austrian study team allow closer scientific scrutiny than was possible in the past.
"For a long time, we considered silicone implants to be inert when they were placed in body," she says. "This research suggests that they are recognized as foreign, and that they may not only start, but fuel, an inflammatory response."
On the other hand, plastic surgeon Bruce Cunningham, MD, tells WebMD the Austrian research falls far short of proving a link between silicone-filled breast implants and autoimmune diseases like rheumatoid arthritis and lupus.
"The fact is that proteins attach to all kinds of biomedical devices implanted in the body," he says. "But it is a huge leap of faith to reach the conclusion that the presence of these proteins is responsible for triggering these autoimmune phenomena."
Study after study has failed to show a link between silicone-filled breast implants and a greater incidence of disease in the women who have them, Cunningham says.
Cunningham is a professor of plastic surgery at the University of Minnesota and the immediate past president of the American Society for Plastic and Reconstructive Surgeons.
"The FDA just approved these devices, after studying the data for the last 14 years," he says. "If they thought for a moment that there was a valid concern about connective tissue disease -- or any disease -- they would never have done that."
Diana Zuckerman, PhD, president of the National Research Center for Women and Families, says FDA decision-makers ignred critical evidence suggesting an increase in autoimmune symptoms among women with implants.
"The disturbing thing about the FDA decision is that there were so many unanswered questions," Zuckerman says. "What was the rush? There is plenty of reason to be concerned that at least some women are having bad reactions to silicone implants."
SOURCES: Backovic, A., Journal of Proteome Research, December, 2006; online edition. Aleksandar Backovic, division of experimental pathophysiology and immunology, Innsbruck Medical University, Innsbruck, Austria. FDA silicone ruling, Nov. 17, 2006. Diana Zuckerman, PhD, president, National Research Center for Women and Families. Renee Carter, National Research Center for Women and Families.
By Salynn Boyles
Reviewed by Louise Chang