In the wake of reports questioning the safety of polyurethane-covered breast implants, medical experts are advising women not to panic. Nor do they advise that women have surgery to remove these implants, which are just one of several types used to enlarge breasts or reconstruct them after a mastectomy.
The scare began earlier this month when information appeared in newspapers about the Food and Drug Administration's analysis of safety data on the foam-covered implants.
The recent FDA study showed that polyurethane breaks down into a chemical called 2-toluene diamine (TDA) in laboratory conditions that simulate those of the human body. Previous studies have demonstrated that polyurethane breakdown outside the body releases TDA, and that TDA can cause cancer of the liver when fed to laboratory animals.
But whether TDA causes liver cancer in people is not known. There are, apparently, no reports in the medical literature that link liver cancer with polyurethane-coated implants.
FDA officials said published reports exaggerated the risk, and deplored the premature release of incomplete information. A statement by the federal regulatory agency called the cancer risk, shown by preliminary analysis, to be "very small -- certainly too small to warrant removing the implants." "If we see the same rate of break down in women that we've seen in the laboratory studies, then the risk of cancer would be less than one in a million over a lifetime of exposure," said Elizabeth Jacobson, deputy director of FDA's Center for Devices and Radiological Health.
The FDA has, however, advised physicians not to use this type of implant until the data are completely analyzed. Bristol-Myers Squibb, owner of the subsidiary company that manufactures the coated implants under the names "Meme" and "Replicon," has issued the same advice and stopped shipment of the devices.
Only a minority of the 2 million women with breast implants have the polyurethane-coated type. Most implants consist of a smooth silicone shell containing silicone gel, salt water, or both. The polyurethane coating was developed to solve a major problem associated with smoother implants: Scar tissue is less likely to harden around the foam-like covering and distort the shape of the breast.
On the market since the 1970s, coated implants now account for about 25 percent of implant sales.
However, questions about them have been raised before -- because of the already-known effect of TDA in animals and because of the difficulties encountered if they have to be removed for medical reasons.
"Polyurethane breaks up in the breast, and if there's an infection, it's hard to get the pieces out," said Dr. Sheri Slezak, assistant professor of plastic surgery at the University of Maryland School of Medicine. She does not use them.
"These implants have proven themselves technically and aesthetically, but there are hazards to be aware of," added Dr. Scott Spear, professor of surgery at the Georgetown University School of Medicine. "I think there are legitimate questions that need to be answered, but I don't think there is any clear evidence that the material poses a significant hazard."
Still, Dr. Spear rates them at the bottom of the safety list.
"I tell women that the safest thing to do is not have an implant," Dr. Spear said. "But most women who come in already know that. They ask me, 'What can I do that is reasonably safe?' "
There are, in fact, many safety concerns relating to breast implants.
Of greatest concern, from Dr. Slezak's point of view, is the possibility that implants can get in the way during mammography, decreasing the likelihood of early detection of breast cancer. The American College of Radiology has declared that "mammography may be more difficult to perform, and it may be less effective" in women with implants.
Other problems include the formation of internal scar tissue, which can tighten around smooth-covered implants, turning the breast into a hard, painful ball. Infection can also occur with implants, and then defy antibiotics. Silicone bags can rupture, spilling silicone gel. Gel can also diffuse through the walls of unbroken bags. Once that happens, silicone lumps can form in the body. Some implant patients have also developed connective tissue diseases like scleroderma and lupus, which they attribute to silicone.
Kathleen Anneken, co-founder of the Command-Trust Network in Kentucky, an information clearinghouse for women with implants, believes her own headaches, joint pains, sun-induced rash and overwhelming fatigue were connected to implants: She's had four sets inserted and removed for various reasons. Following the removal of the fourth and final set, most of her symptoms have disappeared.
"We are in touch with over 5,000 people," Ms. Anneken said, many of whom report similar symptoms which they, too, associate with their implants.