BREAST IMPLANTS AND BREAST CANCER

An estimated 1.5 million to 2.0 million U.S. women have had breast implant surgery since 1962. The safety of breast implants has been questioned, in the popular press and in the courtroom, since the first reports in the mid-1980's that women with these implants developed connective tissue diseases and other disorders. Originally, the implants were assumed to be biologically inactive and therefore safe.

In 1992, the U.S. Food and Drug Administration decided to limit the availability of the implants to women who were undergoing breast reconstruction in controlled clinical trials, until the long-term safety of the implants for all women could be established. In addition, Congress charged NIH with conducting a follow-up study to study the health effects of the implants. In response, DCEG investigators initiated a large-scale study to assess whether silicone breast implants altered the risk of breast cancer, other cancers, and various connective tissue diseases, such as rheumatoid arthritis, Sjögren's syndrome, and scleroderma.

Dr. Louise Brinton, Chief of the Environmental Epidemiology Branch, and colleagues have reported results of the first stage of the analysis in the November issue of Cancer Causes and Control (2000;11:819-827). "This is the largest study with the longest follow-up to date, and we don't see an alteration in the risk of breast cancer for patients with breast implants," Dr. Brinton said. "The women in this study were followed for more than 10 years, and their risk is the same as women in the general population."

Dr. Brinton's results stand in contrast to many previous reports that women with breast implants have a lower risk of breast cancer than women in the general population. Those studies typically followed fewer women for less than 10 years. In addition, "The reduction in breast cancer found in those shorter studies may just be reflecting the intensive screening that women considering implants get prior to their surgery," Dr. Brinton said. "Earlier studies may be reflecting a pre-screening bias. Cases were diagnosed 'early,' creating a larger-than-expected rate of breast cancer during the study's observation period. But in one study, this result did not occur. We found that over the long run, the breast cancer risk appears to be the same as other women."

The DCEG study looked at 13,500 women who received cosmetic breast implants in both breasts between 1962 and 1989. The researchers compared these women to 4,000 women of a similar age with plastic surgery of a different sort, such as face-lifts and tummy tucks. The researchers selected women from 18 plastic surgery practices in six geographic areas: Atlanta, Birmingham, Charlotte, Miami, Orlando, and Washington, DC. Following assurance of patient confidentiality, physicians from these practices agreed to give DCEG investigators access to patients' medical records.

The DCEG researchers reviewed the records of these women and mailed questionnaires asking about their health status. Women with any type of breast implant—silicone gel filled, saline filled, or double lumen (double sac implants with silicone gel in the inner sac and saline in the outer sac)—were studied. None of the implants affected the risk of breast cancer. Although women with implants who developed breast cancer tended to have their cancer detected at slightly later stages than women without implants, breast cancer mortality did not differ significantly between the two groups of women.

Nevertheless, "One of the concerns with the implants is that cancers won't be discovered until they become more advanced," Dr. Brinton said. "We may not have enough precision at the moment to resolve the issue. That's why it's very important to continue to follow these patients to see if the breast cancer death rates change over time."

In addition to continuing to follow breast cancer in these patients, the researchers are continuing to study these women to evaluate the risk of other cancers and connective tissue disorders, as well as causes of death.

Lisa Seachrist