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Silicone breast implants: implications for society and surgeons

Stuart B Renwick

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Abstract - Introduction - Problems with silicone gel breast implants - Mechanical problems - Relationship to autoimmune diseases - Relationship to breast cancer - Summary - Medicolegal settlements in the United States - The future - References - Author's details

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In the last two years, scientific studies have confirmed that there is no significant increase in risk of subsequent breast cancer, connective-tissue disease or symptoms in women with silicone gel-filled breast implants. Despite this evidence, a moratorium (in place since 1992) on the use of these prostheses in the United States has been maintained by the pressure of overwhelming litigation. At the same time, Australian authorities also announced a moratorium, restricting the availability of silicone breast implants. Huge damages awarded by United States courts forced Dow Corning, manufacturer of a large percentage of breast prostheses, to file for Chapter 11 bankruptcy in May 1995. This effectively terminated the major source of implantable silicone for medical use. The withdrawal of implantable silicone and other implantable prosthetic material will be a significant loss for surgeons and society. This paper will highlight the consequences if reasoned scientific data are not relied on by Australian courts to assess claims for damages relating to medical devices. (MJA 1996; 165: 338-341)

Introduction

 In the late 1940s, a family of silicon-based polymers (plastics) was developed. These polymers had a molecular structure of silicon and oxygen atoms with various organic sidechains, which could be varied to make the silicones liquid or solid for use as lubricants, gels, flexible sheeting or solid blocks of low reactivity and great permanency. Silicones were rapidly taken up by surgeons as a compatible material for implanting into the human body.

Breast augmentation was first performed by injecting paraffin wax into the breast and, in 1949, by the implantation of polyvinyl alcohol sponge. As these implants set like a rock after several years, injectable liquid silicone was tried in Asian countries (it was never legal in Australia). However, this produced granulomas with hard lumps and opacities which precluded mammographic detection of breast cancer.

Silicone gel-filled prostheses were first used in 1964 and it has been estimated that about two million have been implanted over 30 years worldwide. The prostheses have been modified to include fixation patches, thinner outer envelopes of silicone, silicone cores with outer envelopes of saline, and textured outer envelopes. Regulations governing the use of breast implants in Australia are shown in Box 1.

Silicones are currently used not only in gel-filled breast implants, but also in ventriculocaval shunts, artificial joints and tendon sheaths, intraocular lenses, cochlear implants, as well as implantable pumps, pacemakers and defibrillators.

Problems with silicone gel breast implants

Mechanical problems

A 1994 study reported that 10% of prostheses needed replacement and, of these, 85% were intact and 15% had bled or had ruptured (i.e., only 1.5% of all prostheses had bled or leaked and 98.5% were intact). 2

Relationship to autoimmune diseases

During the 1980s, there were sporadic references in the literature to single cases or small series of cases where an association between silicone gel implants and autoimmune diseases was claimed. 3-6 The hypothesis that silicone induces connective-tissue diseases was generated from such descriptive uncontrolled studies. 7 Up to June 1993, about 300 patients have been reported worldwide with rheumatic symptoms after receiving gel-filled breast implants. 8 The most commonly reported connective-tissue disease was scleroderma, but several other connective-tissue disorders and vague musculoskeletal symptoms have also been described, particularly vague aches and pains (fibromyalgia), sleep disorders and fatigue -- symptoms which are extraordinarily common in the community. 9

It was not until 1994 that the first definitive studies to examine the relationship between silicone implants and autoimmune disease appeared. Englert et al. identified 556 cases of scleroderma in women who had resided in Sydney between 1974 and 1988, of whom 270 were living and 213 were deceased (73 were "living status unknown"). 10 They reported that the rates of augmentation mammoplasty were similar between the 251 women with scleroderma that they interviewed and 289 matched controls (the study carried a 90% chance of detecting a relative risk of 4.5). These results were validated in 1996 when the authors found no association between silicone breast implants and scleroderma (odds ratio [OR], 1.33; 95% confidence interval [CI], 0.26-6.71, and OR, 1.00; 95% CI, 0.16-6.16, after adjustment for confounders age, socioeconomic status and ethnicity). 7 Validation of augmentation mammoplasty status was possible in 532 of the original 556 cases of scleroderma.

Larger epidemiological studies were conducted in the United States. In 1994, Gabriel et al., from the Mayo Clinic, performed a population-based case-control study of 749 women who had received a breast implant in Olmsted County, Minnesota, between 1964 and 1991. 11 Each subject was matched with two women of the same age who had not had a breast implant, but had had a medical evaluation within two years of the date of the subject's implant. The implant group were followed for a mean of 7.8 years and the control group for a mean of 8.3 years.

The authors sought evidence from the medical records for a diagnosis of any connective-tissue diseases, autoimmune diseases or non-breast cancer, as well as for related symptoms. Only morning stiffness was significantly more common in the implant group. Five women with implants and 10 women without implants were diagnosed with one of the specified connective-tissue diseases. The authors found no statistically significant elevation in the relative risk of any of the specified connective-tissue diseases or other disorders in women with silicone breast implants.

Box 2 shows the conclusion reached in 1994 by the Medical Devices Agency of the United Kingdom Department of Health, which reviewed all the evidence relating to silicone breast implants and connective-tissue disease.

In 1995, Sanchez-Guerrero et al., from Harvard Medical School, reported on a cohort of over 120 000 registered nurses aged between 30 and 55 who had been followed up since 1976. 13 The mean follow-up period after surgery for the 1183 women with silicone breast implants was 9.9 years.The age-adjusted relative risk of definite connective-tissue disease in women with implants was 0.3 (95% CI, 0-1.9). The relative risk of self-reported signs or symptoms of connective-tissue disease for women with implants was 1.5 (95% CI, 0.9-2.4), and the risk of having any one of 41 signs, symptoms or laboratory features of connective-tissue disease was 0.7 (95% CI, 0.3-1.6). The authors concluded that there was no association between silicone breast implants and connective-tissue diseases, or signs or symptoms of these diseases.

The American College of Rheumatology released a statement in October 1995 declaring that these studies provided compelling evidence that silicone implants expose patients to no demonstrable additional risk for connective-tissue or rheumatic disease. 14 The College affirmed that anecdotal evidence, while of importance in drawing attention to a potential problem, should no longer be used to support this relationship in the courts or by the Food and Drug Administration (FDA). They recognised that many women who have received silicone breast implants have musculoskeletal complaints that are also very common in the general population. They had stated in 1994 the importance and great need for scientific analysis of this question, and called upon the FDA and other regulatory agencies to allow professional societies to foster epidemiological studies.

The only study suggesting a possible link was published in February 1996. 15 Hennekens et al. retrospectively reviewed a large cohort of 395 543 health professionals and found 10 830 women who reported breast implants and 11 805 who reported connective-tissue diseases between 1962 and 1991. The relative risk of any connective-tissue disease among those reporting implants was 1.24 (95% CI, 1.08-1.41; P = 0.0015). This indicated a small, but significant, increase in the risk of connective-tissue disease, but provided reassuring evidence against silicone implants being a large-scale hazard. The results fell within the 95% confidence limits of the other two major studies. The authors stress that biases from self-reporting of symptoms (questionnaires were sent to the women after the publicity surrounding the FDA ban) or a higher participation rate in women with such diseases must be considered as alternative explanations for their results.

Relationship to breast cancer

In a population-based non-concurrent cohort-linkage study of 11 676 women in Alberta, Canada, who underwent cosmetic breast augmentation from 1973 to 1986, Berkel et al. found that 41 women with implants had subsequently developed breast cancer. 16 By comparing these women to a cohort of women who had a first primary breast cancer diagnosed between 1973 and 1990, and by applying calendar-year-specific incidence rates of breast cancer, the expected number of breast cancer cases in the implant cohort was 86.2. The standardised incidence ratio was thus 47.6%, significantly lower than expected ( P < 0.01). They concluded that women with silicone breast implants have a lower risk of breast cancer than the general population.

In a reanalysis of the data used by Berkel et al., Bryant and Brasher performed multiple estimates of the standardised incidence ratios on the basis of differing study-eligibility dates, indication periods and types of breast cancer (invasive or invasive plus in situ ). 17 They found substantial differences in the numbers of person-years at risk, resulting in higher standardised incidence ratios than in the original analysis, and concluded that the risk of women with silicone breast implants developing breast cancer was not higher or lower than in the general population.

Summary

Medicolegal settlements in the United States

In view of these findings, it must be asked how silicone breast implants were found wanting and how their main manufacturer was reduced to bankruptcy? The answer lies in the medicolegal settlements and judgments made against the company in the United States ( Box 3). The United States legal processes in the breast implant trials exemplified a growing divergence between science and the law, and the use and abuse of expert witnesses in an adversarial legal system. 20 In just four years, the litigation bar in the United States demolished the largest manufacturer of medical silicone products.

The future

So far, litigation has been aimed largely at the manufacturers of breast implants, but if they were unable to pay could individual surgeons who performed the implants be sued?

What transpired in United States courtrooms and in the United States media, at least at the time of the FDA ban, were judgments allegedly based on anecdote and speculation. 16 Anecdote and fear prevailed over science and were successful. I only hope that Australian courts will admit reasoned scientific evidence and that settlements, if any, are commensurate with damages and not excessive. In Australia, we must maintain scientific objectivity, so that silicone continues to be available for implantation in its many forms.

References

  1. Commonwealth Department of Human Services and Health. Breast implant information booklet. Canberra: AGPS, 1995.
  2. Duffy MJ, Woods JE. Health risks of failed silicone gel breast implants: a 30 year clinical experience. Plast Reconstr Surg 1994; 94: 295-299.
  3. Van Nunen SA, Gatenby PA, Basten A. Postmammoplasty connective tissue disease. Arthritis Rheum 1982; 25: 694-697.
  4. Kumagai Y, Shiokawa Y, Medsger TA, et al. Clinical spectrum of connective tissue disease after cosmetic surgery. Arthritis Rheum 1984; 27: 1-12.
  5. Spiera H. Scleroderma after silicone augmentation mammoplasty. JAMA 1988; 260: 236-238.
  6. Varga J, Schumacher R, Jimenez SA. Systemic sclerosis after augmentation mammoplasty with silicone implants. Ann Intern Med 1989; 111: 377-383.
  7. Englert H, Morris D, March L. Scleroderma and silicone gel breast prostheses -- the Sydney study revisited. Aust N Z J Med 1996; 26: 349-355.
  8. Brooks PM. Silicone breast implantation: doubts about the fears. Med J Aust 1995; 162: 432-434.
  9. Reilly PA. Fibromyalgia in the workplace -- a management problem. Ann Rheum Dis 1993; 52: 249-251.
  10. Englert HJ, Brooks P. Scleroderma and augmentation mammoplasty -- a causal relationship? Aust N Z J Med 1994; 24: 74-80.
  11. Gabriel SE. Risks of connective-tissue diseases and other disorders after breast implantation. N Engl J Med 1994; 330: 1697-1702.
  12. Medical Devices Agency. Silicone implants and connective tissue disease. London: Department of Health, 1995.
  13. Sanchez-Guerrero J, Colditz GA, Karlson EW, et al. Silicone breast implants and the risk of connective-tissue diseases and symptoms. N Engl J Med 1995; 332: 1666-1670.
  14. American College of Rheumatology. Issues Statement on Silicone Breast Implants, 24 October 1995 [press release].
  15. Hennekens CH, Lee I-M, 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.
  16. Berkel H, Birdsell DC, Jenkins H. Breast augmentation: a risk factor for breast cancer? N Engl J Med 1992; 326: 1649-1653.
  17. Bryant H, Brasher P. Breast implants and breast cancer-- reanalysis of a linkage study. N Engl J Med 1995; 332: 1535-1539.
  18. Nocera J. Fatal litigation. Fortune 1995 Oct 16; No 20: 46-66.
  19. Nocera J. Fatal litigation. Fortune 1995 Oct 30; No 21: 137-158
  20. Angell M. Evaluating the health risks of breast implants: the interplay of medical 1513-1518.

Author's details

Sydney Breast Cancer Institute, Royal Prince Alfred Hospital, Camperdown, NSW.
Stuart B Renwick, FRACS, FRCS, Director.
Reprints: Associate Professor S B Renwick, Sydney Breast Cancer Institute, Royal Prince Alfred Hospital, Missenden Road, Camperdown, NSW 2050.

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