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There have been anecdotal claims (informal accounts) that specific connective tissue disorders (CTDs) are caused by silicone gel-filled breast implants. To date, more than two dozen studies have been conducted throughout North America and Europe to evaluate whether there is a link between silicone gel-filled breast implants and various CTDs.1 Consistently, these studies show no convincing evidence that links silicone gel-filled breast implants and "any individual CTD, all established CTDs combined, or atypical connective tissue or rheumatic disease (disease characterized by inflammation of connecting or supporting tissue, such as a ligament, tendon, etc)."1

Click here to read more information from the FDA

In order for a woman considering breast implant surgery to understand what this means for her, it's important to understand a few basic facts about immunology. Immunology is the study of the immune system, a collection of different processes in the body that protect us from harmful substances and disease by seeking out and destroying anything that is "foreign," including viruses and bacteria. Immunology and toxicology, which is the study of the way a chemical or foreign substance may impact the human body, are the two areas of research that I have focused on during my 25 years as a scientist.

Understanding Connective Tissue Disorders

Connective tissue is the material that is found between our cells that gives tissues form and strength.2 Connective tissue disorders (CTDs), a subset of autoimmune disorders, include diseases such as lupus, rheumatoid arthritis, scleroderma, and Sjogren's syndrome. As the name suggests, connective tissue disorders occur when the immune system attacks the body's connective tissues. Many, but not all, connective tissue disorders are rare among the general population.3 Usually, the immune system recognizes our own cells and tissues, and does not attack them. However, when the immune system malfunctions and attacks normal body tissues, the result is one or more of a series of diseases called "autoimmune disorders."

The symptoms of autoimmune disorders – including all CTDs – are generally vague, are common to many other unrelated illnesses, and can vary widely. Some symptoms include fatigue, dizziness, malaise (a non-specific feeling of not being well), memory loss, joint pain and low-grade fever.4 Doctors diagnose CTDs by looking for a specific "cluster" of these symptoms. For example, a patient who complains to her doctor about a facial rash, extreme fatigue, malaise and unexplained fever together may be evaluated for a CTD by her physician.

Due to my background in both immunology and toxicology, along with my long-term experience with medical devices, I became very interested in silicone gel-filled breast implants during the 1990s, when claims surfaced that women with these implants had developed CTDs. Over the past 14 years, I have reviewed the results of the well-controlled, comprehensive studies on the topic, and feel that the existing data support the conclusion that there is no link between silicone gel-filled breast implants and the development or occurrence of CTDs.

In the case of these disorders, it is understandable that individuals might assume a link, because many of the symptoms of CTDs are vague and very common, especially among women of menopausal age. As a result of busy lifestyles, menopause or other common conditions like insomnia, a large percentage of women in the general population – whether or not they have saline-filled or silicone gel-filled breast implants – often experience symptoms of CTDs, such as memory loss, fatigue and malaise. It is important to note that, in general, in well-controlled, reliable studies exploring this issue, women without silicone gel-filled breast implants experienced these symptoms at the same rate as women with silicone gel-filled breast implants. Additionally, confirmed diagnoses of specific CTDs are no higher among women with implants than those without.

Several credible research groups completed comprehensive reviews of studies on the topic of silicone gel-filled breast implants and CTDs in the 1990s. Medical evaluations of potential associations between silicone gel-filled breast implants and CTDs have continued since that time, particularly in Europe.5,6,7 Additionally, several government organizations, review panels and independent organizations, including the Institute of Medicine (IOM), and a special committee established by the United Kingdom's Department of Health – referred to as the Independent Review Group (IRG) – also have conducted comprehensive reviews studying whether there is a link between silicone gel-filled breast implants and serious health issues, particularly CTDs.1,7,8

The IOM (1999) and the IRG (1998) reports concluded respectively that, "There is insufficient evidence to support an association of silicone gel-filled breast implants with defined connective tissue disease"9 and "...if there is a risk of connective tissue disease, it is too small to be quantified."10 In November 2006, the FDA allowed silicone gel-filled breast implants to be re-introduced in the US market following a nearly 15-year voluntary, temporary suspension. During this suspension, the FDA requested additional information to fully establish the safety of silicone gel-filled breast implants – including information about any potential link to CTDs.

See a timeline of the evolution of silicone gel-filled breast implants

Q

If silicone gel-filled breast implants don't cause connective tissue disorders, why is the FDA requiring breast implant manufacturers to continue tracking the incidence of CTDs?

A.

In its November 2006 decision to approve silicone gel-filled breast implants, the FDA required each company manufacturing silicone gel-filled breast implants to conduct a large "post-approval" study of their medical devices.

The FDA's request for each manufacturer to conduct a post-approval follow-up study is a common one – many manufacturers of medical devices and drugs are asked to continue tracking patient experiences with their products for many years after the products are approved for use. The fact that the FDA approved silicone gel-filled breast implants means that the Agency is satisfied, given all of the data presented to them, and that these devices are safe for women in the United States. It is understandable that the FDA wants to ensure there is always current, reliable evidence to address any future questions related to breast implants.

The post-approval studies will be closely monitored by the FDA. The FDA anticipates that data from the studies will provide important information for patients and physicians, and may lead to improved understanding about breast implants.

Q

How do you explain the studies and analyses that DID find links between SBIs and CTDs?

A.

Early in the discussion about silicone gel-filled breast implants and CTDs, individual reports from doctors and patients (called "case reports") accounted for the largest number of published studies on the subject. Case reports should be used to develop theories that can be tested in studies, but they should NOT be used to demonstrate proof of an association between one thing and another.

These early reports did not include information about how the claimed diseases were diagnosed. It is important to remember that the symptoms of CTDs are very common among the general population, and the diseases themselves are difficult to diagnose. A loosely defined set of symptoms was believed to be "caused" or "associated with" implantation of silicone gel-filled breast implants without evidence that the cluster of symptoms was more common in patients with these implants than the general population. This means that there was significant potential for "over-diagnosis" of CTDs among the patients in the studies – particularly when researchers were looking for them. This partly explains why, in several studies and analyses exploring silicone gel-filled breast implants and CTDs, women without implants had a higher incidence of CTDs than we normally see in the general population.

When scientists review a study or analysis, we look for a number of things that help us determine whether the study's results and conclusions are valid. In the case of health-related research, the most important things we look for include:

• The absence of selection bias: "Selection bias" happens when researchers select people to be part of a study who are different from each other in key ways. This can alter the accuracy of study results.
• Control groups: A group of patients who serves as a comparison group in a study. Usually, the "control group" does not receive the treatment or device in question, and can then be compared to the "treatment group" to determine an effect.
• Study size: Any study should include enough people to determine a pattern and eliminate the potential that the individuals included in the study are outside of the norm.
• Use of well-defined diagnostic criteria: In studies where researchers are looking for a specific condition or disease, they should clearly state what symptoms and measures they are using to diagnose that disease.
• Temporal relationship between exposure and condition: It is important for researchers to note whether symptoms of a condition developed before or after exposure to a specific treatment or device and, if symptoms developed after, if the length of time suggests other factors could be involved.
• Control for other risk factors: The question here is, “Did researchers take into account other factors that could have caused the condition?” An easy example of this is in a study looking at whether pollution causes lung cancer, did researchers ask study participants if they smoke?

In my review of studies that identified a link between silicone gel-filled breast implants and any CTDs, I noted significant issues related to bias, the absence of appropriate control groups, the absence of consistency in the way diseases were defined, poor response rates, lack of consideration of confounding factors and limited study size – particularly in early studies. However, the epidemiological evidence as a whole (considered by the review documents described above) is comprised of numerous, well-conducted, large, long-term studies with appropriate control groups, absence of obvious bias, etc. The results of these studies are consistent in finding no association between breast implants and CTDs.1,5,6,7,8,9,10

Q

If my silicone gel-filled breast implant "leaks," would it be POSSIBLE for the silicone to cause an immune response in my body? What is the likelihood?

A.

A number of studies have been conducted to determine the potential for silicones of various types to cause an immune response in the body. These were reviewed by the governmental agencies that considered the possible association between silicone gel-filled breast implants and CTDs and included in the committee's conclusions. In 1993 and 1994, the results from a comprehensive set of studies conducted under the US National Toxicology Program were published. These studies, which measured not only immune function, but the ability of the immune system to deal with foreign invaders, did not reveal a significant risk for changes in the immune system after exposure to silicones. Researchers did not see any reduction in the ability of the immune system to fight disease (cancer and two bacterial infections).

Further, a number of animal studies have shown that the immune system does not generate specific responses to silicone, even after significant exposure.

Click here for expert content about animal studies

Finally, it is important for women to keep the risk of developing a CTD in perspective. In their comprehensive review of recent studies on the subject, the British IRG concluded that "the risks [of developing a CTD following silicone gel-filled breast surgery] are substantially lower than the risk of thrombosis following the use of the oral contraceptive pill or the risk of major gastric bleed following the use of aspirin or aspirin-like drugs."10

Q

Where can I find more information on this subject?

A.

• Studies that have explored the safety of silicone gel-filled breast implants and their relationship to connective tissue disorders and other diseases Click Here for a comprehensive list of studies
• The British IRG published a summary of the information considered in their review and comments here or here
• The UK's Medicines and Healthcare products Regulatory Agency (MHRA) has published a paper titled "Breast Implants: Information for Women Considering Breast Implants" Read the paper
• Wikipedia has an easy-to-view, comprehensive list of government studies examining the health implications of breast implants Read the article

1 Lipworth L, Tarone RE, McLaughlin J. "Silicone Breast Implants and Connective Tissue Disease: An Updated Review of the Epidemiologic Evidence." Annals of Plastic Surgery 2004 52(6):598-601.
2 http://www.wrongdiagnosis.com/organ/connective_tissue.htm
3 http://www.niams.nih.gov/hi/topics/connective/connective.htm#alteration
4 http://www.nlm.nih.gov/medlineplus/ency/article/000816.htm
5 Breiting VB, Holmich LR, Brandt B, et al. "Long-term health status of Danish women with silicone breast implants." Plast Reconstr Surg 2004;114(1):217-226
6 Fryzek JP, Holmich L, McLaughlin JK, et al. "A nationwide study of connective tissue disease and other rheumatic conditions among Danish women with long term cosmetic breast implantation." Ann Epidemiol 2007 in press.
7 Brinton LA, Buckley LM, Dvorkina O, Lubin JH, Colton T, Murray MC, Hoover R. "Risk of connective tissue disorders among breast implant patients." Am J Epidemiol. 2004;160(7):619-27
8 Janowsky EC, Kupper LL, Hulka BS. "Meta-analyses of the relation between silicone breast implants and the risk of connective-tissue diseases." N Engl J Med/. 2000;342:781-790
9 Bondurant S, Ernster V, Herdman R. "Safety of Silicone Breast Implants, Report of the Committee on the Safety of Silicone Breast Implants, Institute of Medicine." Washington, D.C.: National Academy Press, 1999.
10 Independent Review Group, Rogers J, et al. "Silicone Gel Breast Implants: the Report of the Independent Review Group." Cambridge, England: Crown; 1998 Report of the IRG, 1998.
11 Williams, HJ, et. al., "Breast implants in patients with differentiated and undifferentiated connective tissue disease." Arthritis Rheum. 1997; 40(3): 437-440.
12 Williams, HJ and Weisman, MH, "Silicone breast implants in patients with undifferentiated connective tissue disease" [abstract]. Arthritis Rheum. 1994; 37(9 - supplement):S422.