Breast Implant Safety

by Food and Drug Administration (FDA)

Recently published studies have shown that women with silicone gel-filled breast implants do not have a greatly increased risk of some well-defined autoimmune diseases, which were among the serious health concerns surrounding the devices. These include potentially fatal connective tissue diseases such as scleroderma and lupus erythematosus.

The new studies do not, however, rule out the possibility that a subset of women with implants may have a small increased risk of these conditions, or that some women might develop other immune-related symptoms that don't conform to "classic" disease descriptions.

Nor did the studies address other important safety questions, including implant rupture rates and the incidence of capsular contracture (shrinking of scar tissue around the implant, which can cause painful hardening of the breast or distort its appearance). Answers to these and other questions await the results of new or ongoing studies.

Widespread reports of adverse reactions to silicone gel-filled implants and a lack of evidence supporting their safety led the Food and Drug Administration to order the devices off the market in April 1992. They remained available only to women in clinical studies, mostly women seeking breast reconstruction after breast cancer surgery. Saline-filled implants were allowed to remain on the market for all uses.

Reasons for New Studies

Breast implants had been marketed since the early 1960s — several years before the first medical device law was enacted in 1976, charging FDA with regulation of medical devices. Every year, thousands of American women had implant surgery for augmentation (to enlarge or reshape their breasts) or for reconstruction following mastectomy (removal of the breast) to treat breast cancer. Most of the implants consisted of a rubber silicone envelope filled with silicone gel; about 10 percent were filled with saline (salt water).

Under the 1976 law, implants and many other devices already in use were allowed to remain on the market, with the understanding that the agency would at some time ask manufacturers to submit scientific data showing these "grandfathered" products were safe and effective.

FDA requested this information for silicone gel-filled implants in April 1991 in response to a growing number of adverse reaction reports that raised safety concerns about the devices. The data submitted did not prove the devices safe, as required by law, so the agency restricted their use to clinical trials designed to resolve the safety questions.

Between Jan. 1, 1985, and Sept. 17, 1996, FDA received 103,343 adverse reaction reports associated with silicone breast implants and 23,454 reports involving the saline implants. Because these figures come from all databases, there may be a few duplicate reports. The reports included risks clearly associated with the devices, as well as adverse effects attributed to the implants, but not proved to be linked to them.

Silicone Implant Studies

Some recent studies comparing the rates of immune-related diseases in women with implants versus those without implants have provided reassurance that women with implants are not at a greatly increased risk of these disorders.

The largest of these retrospective, or "look-back," studies is the Harvard Nurses' Health Study. The study used data from 87,501 nurses followed for other research purposes from 1976 through May 31, 1990, before there was widespread media coverage of the possible association between breast implants and connective tissue disease. None of the women had connective tissue disease at the start of the study.

In an article published in the June 22, 1995, New England Journal of Medicine, the researchers reported that 516 of the nurses had developed definite connective tissue diseases. Women with breast implants numbered 1,183. The types of implants included 876 silicone gel-filled, 170 saline-filled, 67 double lumen (silicone gel-filled implants with a saline-filled outer envelope), 14 polyurethane-coated, and 56 of unknown type. Only three of the 516 women with definite connective tissue diseases had implants (one silicone-gel filled, one saline, and one double lumen).

The authors reported they "did not find an association between silicone breast implants and connective tissue disease, defined according to a variety of standardized criteria, or signs and symptoms of these diseases."

Similarly, a 1994 study conducted at the Mayo Clinic found no increased risk of connective tissue diseases among implant recipients. The investigators based their conclusion on comparison of the medical histories of 749 women with breast implants in Olmsted County, Minn., with a similar group of women who did not have implants.

"Because of the limitations in the size and type of the studies, however, the true risk of these diseases is not known," says S. Lori Brown, Ph.D., a research scientist officer in the epidemiology branch of FDA's Center for Devices and Radiological Health. "Although the criteria others may be using to assess those studies show that some concerns are eliminated," Brown says, "unfortunately, they don't rule out a small, but significant, increased risk."

An immunology and epidemiology expert, Brown explains that an inherent problem in the studies is that some connective tissue diseases are extremely rare. "If you have a disease that has an incidence of 1 in 100,000 in the general population, for example, and you do a study of 750 women with implants, like the Mayo Clinic Study, then you wouldn't really expect to see even a single case of that disease," she says, "unless there's an exceedingly high — more than a hundredfold — increase in risk."

Small studies like these can rule out huge risks, but not smaller, yet significant risk increases that would only show up in studies that include several thousand women with implants, Brown says. Nor do the studies fully examine or answer whether the implants might in some women lead to symptoms not typical of classical disease manifestations.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.