Breast implants and cancer risks (professionals)

National Cancer Institute Breast Implant Study: Fact Sheet

In 1992, researchers at the National Cancer Institute (NCI) initiated a study on the long-term health effects associated with silicone breast implants. It is estimated that between 1.5 million and 2 million women in this country have had breast implants since they first appeared on the market in 1962.

One of the longest and largest studies to date on the health effects of implants, the NCI report involves 13,500 women with an average follow-up time of 13 years. Most previous investigations have looked at the health effects over a shorter time period, typically less than 10 years, and have been too small to evaluate uncommon diseases.

In addition, earlier reports did not include detailed information about types of implants or risk factors affecting health, such as medical history, screening practices, and lifestyle behaviors all of which are included in the current study.

Another unique feature of the NCI study is that the investigators compared the health risks of the implant patients to both the general population and other plastic surgery patients. Prior reports have used only the general population as a comparison group.

The purpose of the NCI study is to evaluate the effect of implants on the risk of:

  • Developing breast cancer;
  • Developing cancers other than breast;
  • Dying from all causes of mortality; and
  • Developing connective tissue disorders.

The results will be published in various scientific journals. As the publications appear in the literature, the findings will be summarized at the end of this fact sheet.


Breast implants were first marketed in the early 1960s, before the 1976 Medical Device Amendments to the Food, Drug and Cosmetic Act required that medical devices be shown to be safe and effective. Silicone was initially assumed by manufacturers to be biologically inactive and, therefore, to have no harmful effects. However, cases of connective tissue disorders and cancers were reported in several short-term studies.

Because there were few reports on the long-term safety of implants, in 1992, the Food and Drug Administration(FDA) restricted the use of silicone gel breast implants to controlled clinical trials of women seeking breast reconstruction. That year, Congress also directed the National Institutes of Health to undertake a large follow-up study to assess the long-term health effects of exposure to silicone breast implants.

Types of Implants

Implants are soft silicone sacs or shells, inflated with either saline solution (salt water) or a synthetic silicone gel. Until the FDA ban in 1992, 90 percent to 95 percent of the implants contained the silicone gel because it had a more pleasing look and feel than the saline-filled implants. Since the 1992 ban, 90 percent to 95 percent of the implants have been saline-filled. Currently, it is not known how many women have silicone vs. saline implants, but women with both types are included in the NCI study.

Previous Studies

About 80 percent of breast implants in the United States are for cosmetic reasons and 20 percent for breast reconstruction after breast cancer surgery. The majority of previous studies have focused on women who received implants for cosmetic reasons.

  1. Breast Cancer Risk

A number of previous studies have evaluated the relationship between breast implants and subsequent breast cancer risk. Most have shown that the risk of developing breast cancer is less among women with implants compared to women without implants. In several of the studies, the size of the reduced risk was as much as 50 percent to 60 percent. However, the vast majority did not have enough detailed information on patient characteristics that could affect the development of breast cancer, and had follow-up times of less than 10 years.

  1. Stage at Diagnosis of Breast Cancer

Some clinical studies have suggested that women with breast implants have more advanced breast cancer at diagnosis than women without breast implants. This is because implants have been reported to decrease the ability to detect breast lesions, with either clinical examination or mammography. However, in two larger epidemiologic studies, there did not appear to be differences in stage at diagnosis or survival rates among the two groups.

  1. Mortality

No prior studies have evaluated all causes of mortality of breast implant patients but, instead, have limited their analyses to mortality from breast cancer. Compared to the general population, no increased risk in breast cancer mortality for implant patients was observed

  1. Types of Implant

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