Reviews of literature

In the UK
Department of Health review, 1992
This review by the Independent Expert Advisory Group (IEAG), set up by the UK Department of Health, concluded that there was no evidence of an increased incidence of connective tissue disease associated with silicone gel breast implants. It did, however, recommend that a registry of implanted patients should be set up because of the general anxieties raised*. The group's report was published in 1993 'Evidence for an association between the implantation of silicones and connective tissue disease' (300Kb).

* The UK Breast Implant Registry (UKBIR) (formerly the National Breast Implant Registry) was set up at the Wessex Centre for Plastic and Maxillofacial Surgery at Odstock Hospital in Salisbury (now the Odstock Centre for Burns and Plastic Surgery, Salisbury District Hospital) in 1993. A pilot study to look at long term follow up of women registered with the Registry indicated that only a limited number of implanted women were willing to take part in follow up. This low level of participation meant that the results of any future studies would be of limited value. Based on this conclusion the decision was made to close the registry at the end of March 2006.

Department of Health review, 1994
A second analysis, reviewing scientific papers written on the possible link between silicone gel breast implants and connective tissue diseases, was prepared and published by the Medical Devices Agency (a forerunner of the MHRA). The review concluded that results from clinical or scientific studies did not demonstrate an increase in the incidence of connective tissue disease in implanted patients, compared with the unimplanted population as a whole. The report was published in 1994: 'Silicone implants and connective tissue disease' (256Kb).

Independent Review Group, 1997
The Independent Review Group (IRG) was established in May 1997 in response to concerns expressed by women in relation to silicone gel breast implants. The Chief Medical Officer, at the request of the Minister of Health, Baroness Jay, set up the IRG with the remit: ‘to review the evidence relating to the possible health risks associated with silicone gel breast implants, to examine the issues relating to pre-operative patient information, and to report to the Chief Medical Officer on its conclusions.’ In fulfilling the remit, the IRG took a fresh look at the existing and emerging scientific evidence for a link between silicone gel breast implants and effects on health. Additionally, the IRG gathered evidence on the quality and quantity of information routinely provided to women about to undergo breast implantation. It made nine recommendations, detailed on pages 6-7 of the report, published in July 1998 (673Kb).

The IRG considered immense amounts of complex evidence and reached a number of conclusions:

• There is no histopathological or conclusive immunological evidence for an abnormal immune response to silicone from breast implants in tissue.
• There is no epidemiological evidence for any link between silicone gel breast implants and any established connective tissue disease. If there is a risk of connective tissue disease, it is too small to be quantified. The IRG cannot justify recommending further epidemiological studies to investigate this hypothesis.
• Good evidence for the existence of atypical connective tissue disease or undefined conditions, such as ‘silicone poisoning’ is lacking. It is possible that other conditions such as low grade chronic infection may account for some of the non-specific illnesses noted in some women with silicone gel breast implants.
• The overall biological response to silicone is consistent with conventional forms of response to foreign materials, rather than an unusual toxic reaction.
• There is no evidence that children of women with breast implants are at increased risk of connective tissue disease.
• The IRG recognised that there were issues such as the precise incidence of rupture where the scientific data were incomplete so that rigorous conclusions could not be drawn.

Reviews carried out in other countries
The US Food and Drug Administration (FDA) published an update on the safety of silicone gel-filled breast implants in June 2011 (external link).

Reviews have been carried out by groups outside the UK including Canada (Canadian Expert Advisory Committee review, 1992), France (ANDEM, 1996), USA (US National Science Panel, 1997-8, and Institute of Medicine, 1999), and the Scientific Technical Opinions Assessment (STOA) report commissioned by the European Parliament.
A clear consensus emerged from these independent scientific reviews that there is no evidence of a causal link between the implantation of silicones and connective tissue disease. A summary of these reviews is available: Silicone gel breast implants: systematic reviews carried out in other countries (22Kb).