The safety of silicone breast implants is based on a meta-analysis of selected studies. Would you consider this adequate proof?
According to the latest studies, based on a meta-analysis of old data, silicone implants do not cause connective tissue diseases. Still, there is uncertainty among certain researchers. Silicon-based polymers (plastics) were first introduced in the late 1940s. Early on, chemists found that the molecular structure of these polymers could be varied to make the silicones liquid or solid compounds depending on their use as lubricants, gels, flexible sheeting or solid blocks. Because of these variable properties, surgeons embraced silicones as a compatible implant material. Replacing earlier implants made of paraffin wax, injectible liquid silicone was first used for breast implants in Asia. Early results included granulomas with hard lumps and masses that interfered with mammography. Improved, gel-filled silicone implants were first used in 1964. Worldwide, over the following 30 years, about two million silicone breast implants were put into use.
Historical Background
In 1976, legislation was passed giving the Food and Drug Administration (FDA) responsibility to oversee the safety of medical devices, including breast implants. Because implants had been in use since 1964, they were presumed to be safe and their use was permitted. While it was known that implants could rupture, toxicity studies in animals suggested that there was no known toxicity. In 1982, FDA officials recommended additional studies to evaluate the safety of implants, and in 1988 the FDA mandated these studies. This mandate wasn't enforced until 1991 when the question of breast implant safety and the possible association with connective tissue disease began to get public attention.
A Question of Safety
On the recommendation of two advisory committees, the head of the FDA, David Kessler, asked for a voluntary moratorium on silicone breast implants in 1991. Citing failure by the manufacturers to provide adequate data proving implant safety, Kessler banned their use in 1992 with the exception of clinical trials using gel-filled silicone implants for breast reconstruction after cancer surgery.
In 1993, nearly 9,000 individuals filed lawsuits against the silicone manufacturer Dow Corning, claiming medical injury from their implants. Their primary complaints were symptoms of autoimmune connective tissue diseases and problems related to ruptured implants. In the following years the number of claimants exceeded 400,000 and Dow eventually filed bankruptcy.
Meta-Analysis of Data
In testimony presented as part of the Dow-Corning trials, experts presented data showing that with the possible exception of Sjogren's syndrome, silicone breast implants do not cause connective tissue disease. The analysis was based on published studies written in the English language that may or may not have had ties to pharmaceutical companies. However, research has shown an improvement in connective tissue disease symptoms in women whose implants were removed, antinuclear antibodies and antibodies to silicone molecules have been found in women with implants.
In conclusion, the most recent epidemiologic investigations, including studies from Denmark and Australia, are in agreement that there is no evidence of an excess of any individual connective tissue disease in women with implants when compared to women of the same demographics without implants. The only study suggesting a possible link between silicone implants and connective tissue disease was published in February 1996. In this study researchers reviewed the records of nearly 400,000 health professionals and found the relative risk of those with implants developing connective tissue disease was 1.24, which is a small but significant increase. The study's authors felt that because symptoms were self-reported by patients, there may have been bias due to the publicity of the lawsuits.
Similar to the questions and studies of other suspected environmental triggers such as vaccines, the questions regarding the safety of silicone implants remain a matter of debate. Analyzing data from a time when scientific studies were destroyed if the results strayed from those expected by the study's financiers lends itself to further speculation. When Marcia Angell, former executve editor of the New England Journal of Medicine, resigned and wrote her expose of the peer-review process in her book Science On Trial, it became clear how pharmaceutical ties can influence any given report.
Resources:
Stuart Renwick, Silicone breast implants: implications for society and surgeons, eMJA, The Medical Journal of Australia, 1996, MJAl 1:338-341, article published online at http://www.mja.com.au/oublic/issues/sep16/renwick/renwick.html and accessed December 11, 2006.
Lipworth L, Tarone RE, MdLaughlin JK, Silicone breast implants and connective tissue disease: an updated review of the epidemiologic evidence, Ann Plast Surg, 2004 Jun; 52(6): 598-601.
Silicone Breast Implants in Relation to Connective Tissue Diseases and Immunologic Dysfunction, Executive Summary of Report of National Science Panel, http://www.fjc.gov/BREIMLIT/mdl926.htm
Chem Cases, Kennesaw State University, http://www.chemcases.com/silicon/sil17one.htm
Henneckens CH, Lee, I, Cook NR, et al. Self-reported breast implants and connective-tissue diseases in female health professionals. A retrospective cohort study, JAMA 1996; 275:616-621.
All about silicone breast implants, http:www.implantforum.com/silicone/
