Are Breast Implants Safe?

Diana Zuckerman, PhD

In This Article

Health Risks

The IOM report concluded that local complications are the primary health concern of breast implants. These complications range from minor to serious -- for example, infections can be easily treated or can cause toxic shock syndrome that can cause death or gangrene.[8] The most common complications, such as scarring, asymmetry, loss of sensation, pain, hardness, and the need for additional surgery,[4,9] are usually not life-threatening but they can affect the quality of life -- and since implants' only benefits are to improve the quality of life, these complications should not be dismissed lightly.

All implants are "foreign bodies," and the woman's body reacts by forming a capsule of scar tissue around the implants that can become too tight for the implant. If that occurs, the breasts can become very hard, misshapen, and cause mild discomfort or severe pain. This complication, called "capsular contracture," is widely acknowledged; the controversy is about how often it happens and how serious it is. The most likely treatment is to remove and replace the implants, but manufacturers' research indicates that the replacement implants are likely to cause even more complications than the original implants.[10] Also, additional surgery comes with additional risks and the expense can be much greater than the original surgery.

Surgical risks are not a 1-time risk, since breast implants will eventually break and need to be removed and possibly replaced. Saline implants are removed because they quickly deflate; silicone gel implants require removal because the silicone will eventually leak out and the gel can migrate outside the breast area.[11] It has been reported that some implants break during the first few months or years, and some last more than 15 years. The IOM report suggested that implants do not last a lifetime, but did not draw conclusions about the rupture rate. A study conducted by FDA scientists that was published after the IOM report found that, among "satisfied" women who had not sought to have their implants removed, most had at least 1 broken implant within 15 years.[12] MRIs indicated that silicone migrated outside of the breast capsule for 21% of the women who had broken implants, even though the women had not sought treatment for the problem.

Although the health risks of a ruptured implant are the subject of controversy, the "local complications," such as infection or pain, are well-documented. If the silicone migrates outside the scar tissue, it can destroy healthy breast tissue.[4] Women with ruptured silicone implants can lose breast tissue as part of the removal surgery; in some cases, this may result in surgery that is similar to a mastectomy.[4] However, there are no published data on how often this occurs.

The IOM report's analysis of 17 epidemiologic studies of autoimmune diseases, and a related meta-analysis of 20 studies (16 of which were the same studies that IOM reviewed), all available prior to 1999, concluded that implants probably do not cause a substantial increased risk for these diseases. However, a careful assessment of these studies indicate that several were never peer-reviewed, and most were not appropriately designed to study rare diseases or diseases that take many years to develop. For example:

  • Five of 20 studies[13,14,15,16,17] cited in the meta-analysis were not published in peer-reviewed journals. Instead, they were papers presented at scientific meetings or unpublished doctoral dissertations.

  • The studies included in the IOM report and in the meta-analysis do not provide a comprehensive evaluation of diseases among breast implant patients. Most evaluate a few connective-tissue diseases, including such rare diseases as scleroderma.[13,18,19,20,21,22] Only 6 of these studies evaluate the "atypical" connective-tissue disease symptoms or fibromyalgia-type symptoms that many patients report, and the largest of these studies found a significantly higher risk for women with implants compared with controls.[19]

  • Only 1 of the studies was based on a medical exam done for the study.[18] Most of these studies instead relied on medical records, which might omit vague symptoms that would be reported in the early stages of disease. Several studies relied on self-report, but only the 1 study that reported a significant risk due to implants was criticized by the IOM because it was based on self-report.[19] In contrast, studies that relied on self-reports regarding whether a woman had implants or when she got implants were not criticized as potentially inaccurate, even when the "Harvard Nurses' Study" included reports of women having implants since the 1950s -- the decade before breast implants were invented.[23]

  • Two of the studies relied on hospital records,[22,24] yet most autoimmune diseases do not require hospitalization during the early stages.

  • Virtually all the studies included women who had implants for a short period of time, such as a few months or years. One of the most widely praised of the studies, the "Harvard Nurses' Study," included women who had implants for as briefly as 1 month.[23] Another study included only 250 women, who had implants for an average of 30 months.[25] If implants cause connective-tissue diseases, it would be expected that the disease would develop over a period of years. Therefore, an appropriately designed study would include women who had implants for at least 10-15 years, and none of the studies in the meta-analysis or IOM report include such a population.

  • Many of the samples are small and, thus, have limited statistical power to detect increases in the rates of the rare diseases studied, even increases as large as 50% to 100%. For example, the study by Park and colleagues,[18] published in 1998, includes only 317 implant patients who had implants for an average of 5.7 years. The authors acknowledged that a health risk would have to exceed 320% for reconstruction patients and 1600% for augmentation patients in order to be statistically significant. Similarly, the authors of the often-quoted "Mayo Clinic Study" estimated that they would need to have studied 62,000 women with implants for an average of 10 years to detect a 100% increase in rare diseases such as scleroderma; instead, their study included less than 1000 women who had implants for an average of less than 8 years.[26]

  • Older implants (from 1964-1975) were made of a thicker silicone shell than newer implants. Those implants were less likely to "bleed" silicone through the shell or to break.[12] Therefore, studies with women who had implants for a wide range of years would not be expected to show a "dose" response; yet, the lack of a dose response was interpreted as further evidence that implants do not cause systemic disease.

  • Most of the studies do not specify whether women "with implants" had kept those implants or had them removed. In at least 1 of the studies, women were included in the study even if they had their breast implants removed shortly after they got them.[23] The other studies do not mention whether women who were identified by medical records as having implants still had them years later. Those omissions potentially bias the findings because women who had implants removed do not have the same amount of exposure as women who have implants continuously.

Even with these methodologic biases, many of the 20 studies indicated an increase in some autoimmune diseases or symptoms, but only 1 -- the largest study (which also included women who had implants for the longest period of time) -- indicated that the difference was statistically significant. That study was conducted at Harvard on women who were health professionals, but the study was criticized for relying on self-reported health information.


In addition, 2 European studies indicated that breast surgery (whether for breast implants or to reduce the size of breasts) was associated with increased risk of scleroderma, rheumatoid arthritis, and other autoimmune diseases.


Overall, the most important limitations of these studies are the following:

  • They used medical records and self-reports rather than clinical exams.

  • They focused on classically defined autoimmune diseases and did not study most other diseases or atypical types of autoimmune disease.

  • Most studies included samples that were too small to meaningfully study increases in the rare diseases they were studying.

  • Most of the women in most of the studies had implants for too short a period of time to develop and be diagnosed with the serious illnesses that were the major focus of the studies. Since connective-tissue and autoimmune diseases may take years to develop and be diagnosed, studies that include women who had implants for just a few months or years cannot determine whether breast implants increase the long-term risks of getting these diseases.

The data from these studies clearly support the view that most women do not become ill from well-defined autoimmune diseases after having implants for a short period of time. However, any conclusions about the long-term safety of implants in terms of systemic disease are premature.

Perhaps most important, while the scientific information about silicone gel implants that was available to the IOM and to other experts has been relatively limited, 3 new studies published in May 2001 found statistically significantly increased health risks that raise questions about the long-term safety of implants. One of these studies, conducted by FDA scientists, found a statistically significant link between ruptured silicone gel implants and fibromyalgia and several connective-tissue diseases.[11] This study of patients who had silicone breast implants for at least 6 years found that when the silicone had migrated outside of the scar tissue surrounding the implant, women were significantly more likely to report that they had been diagnosed with fibromyalgia, dermatomyositis, polymyositis, Hashimoto's thyroiditis, mixed connective-tissue disease, pulmonary fibrosis, eosinophilic fasciitis, or polymyalgia. The association with disease remained even after controlling for patient's age, implant age, location, and implant manufacturer.

Another study, of 95 women who had silicone gel-filled breast implants and rheumatologic symptoms, found that the symptoms improved in 42 (97%) of the 43 women who had their breast implants removed.[27] In contrast, rheumatologists reported that rheumatologic symptoms worsened in 50 (96%) of the 52 women who did not have their implants removed. This important study, presented at the American College of Epidemiology (1998) by a scientist at the National Cancer Institute (NCI), has not yet been published.[27]

Breast implants interfere with the detection of breast cancer because implants can obscure the mammography image of a tumor.[28,29,30] Implants therefore have the potential to delay the diagnosis of breast cancer. Although mammography can be performed in ways that minimize the interference of the implants, approximately 30% of the breast tissue will still be obscured.[28] Mammograms tend to be considerably less accurate and are sometimes very difficult to perform if the woman has capsular contracture.[29,30]

There is no research evidence that implants cause breast cancer, but the delay in diagnosis could potentially necessitate more radical surgery or could be fatal. In contrast, a recent meta-analysis performed by Dow Corning, the manufacturer of silicone for implants, found that women with implants were less likely to have breast cancer than other women.[31] Dow Corning's meta-analysis, reported on Medscape in May 2001 under the headline "Silicone Breast Implants May Protect Women Against Breast Cancer," did not include the largest study of women with breast implants, conducted by the NCI and published in 2000.[32] In contrast to the Dow Corning study, the NCI study found no difference between women with implants and other women -- neither an increase nor a decrease.

Very few published studies have medically evaluated enough women with implants for enough years to determine whether implants cause other systemic diseases in the long-term. Two recent federally funded studies by scientists from the NCI have demonstrated a link between implants and cancer, lung diseases, and suicide. One of the studies found that women with breast implants are more likely to die from brain tumors, lung cancer, and suicide compared with other plastic surgery patients.[33] The other study found a 21% overall increased risk of cancer for women with implants, compared with women of the same age in the general population.[34] The increase was primarily due to an increase in brain cancer, respiratory tract cancers, cervical cancer, leukemia, and vulvar cancer. The dramatic findings regarding lung disease and brain cancer were described as "unexpected" by the authors, but the findings are consistent with other newly published research. For example, the previously described FDA study of women with ruptured breast implants reported an increase in pulmonary fibrosis for women with ruptured and leaking implants,[11] and another recent NCI study reported an increase in fatal lung diseases.[33] A recent case report, published by the Royal Academy of Medicine in Scotland, found that a woman with a broken silicone gel implant in her calf was coughing up silicone that was identical to the kind in her implant.[35] The physicians involved believe that this case report suggests that silicone from a ruptured gel implant can migrate to the lungs.

Unlike many other studies of women with implants, the federally funded epidemiologic studies controlled for potentially confounding variables such as smoking and social class and included 2 comparison samples: the general population of women in the same age range, and a population of other plastic surgery patients. The results of the 2 NCI studies indicated that women with breast implants, like other plastic surgery patients, tend to live longer than other women, apparently because women who will undergo plastic surgery tend to have relatively good baseline health and can afford adequate healthcare. However, implant patients were more likely to die from the diseases mentioned above than other plastic surgery patients. Therefore, a recent article in Medscape (April 26) titled "Augmentation Mammoplasty Associated with Reduced Mortality" was misleading.


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