Breast implants are textured silicone bags and can be filled with saline (salt water) or silicone gel. Implants are often referred to as prostheses. Research into the use of different materials to make implants is always ongoing.

Saline (salt water) has the advantage of not causing any problems if it leaks out into the body. However, saline-filled implants do not have the natural feel of silicone-filled implants and give a less realistic reconstructed breast. Saline implants are more likely to leak or wrinkle than silicone implants and can make breast x-rays slightly more difficult to read.

Silicone implants are very commonly used in the UK. These implants are essentially bags of silicone gel enclosed in a thin silicone rubber case. They are designed to feel soft and flexible, like a natural breast, and there are many different types. They can be breast-shaped or rounded, and filled with solid or liquid gel.

The silicone gel filling makes the breast feel more natural than saline. However, there have been some concerns about possible health risks if silicone leaks from the implant. If a silicone implant ruptures, surgery may be needed to remove the implant. Like saline, silicone implants can appear cloudy on x-rays, making mammograms slightly more difficult to read. It is possible to get a good mammogram of a breast containing an implant, but the radiographer needs to be told that an implant is there.

Some newer types of prostheses contain solid silicone gel, and it is hoped that these will be safer.

Silicone implants have been used for many years for breast enlargement and are very popular. However, some women worried that they developed autoimmune illnesses, such as rheumatoid arthritis, or even cancers, as a result of having silicone implants.

Most problems have been associated not with silicone implants, but with liquid silicone injected directly into the breast. Silicone injections are now banned in the US and the UK.

A lot of research has been carried out to see whether silicone implants cause health problems. No link has been found between silicone implants and the development of cancer in humans. The American advisory body on drugs – the Food and Drug Administration (FDA) – banned the use of silicone implants in the United States several years ago when the doubts were first raised. They are now being used in the US again, but only for women in research studies. A statement from the American National Institute of Health in October 1997 said: 'There is no convincing evidence that a silicone implant causes cancer or autoimmune disease.'

In the UK, the Department of Health asked medical specialists to assess the safety of silicone implants several times in recent years. The last occasion was in July 1998. Each time, after carefully reviewing all the available information, they found there is no good evidence of an abnormal immune response to silicone and no evidence for a link with connective tissue disease. They therefore believe that there is no reason to stop using silicone implants.

All breast implant operations are now recorded on a form which is sent to the UK Breast Implant Registry. Any side effects are reported. If problems occur, all the women who have implants can then be contacted and action can be taken.

It is important to talk through any concerns with your breast care nurse, surgeon or a cancer support organisation before you have an implant.

Silicone implants often need to be changed after 10–20 years, as the outer covering becomes weak and may start to allow the silicone to leak. If you have an implant it may be necessary to change it if you:

• put on, or lose weight
• have a capsular contracture (formation of tough, fibrous tissue around the implant)
• have an infection.

It is very difficult to damage implants – normally only a severe chest injury would do this. So you can carry on with all your normal activities, including things like sports and air travel, without worrying that it will affect your implant.