A report issued Friday cautions against the likely return of silicone breast implants to the U.S. market, warning that companies have not performed long-term safety studies in breast cancer patients.

The FDA is expected to soon clear two companies’ silicone implants for U.S. sales after a nearly 14-year partial ban. Friday’s report, issued by the National Research Center for Women and Families--an organization that has vehemently opposed lifting the ban on silicone breast implants -- concludes that the companies have not properly studied the implants’ safety in women with cancer.

“The main focus of this report is really the missing data, the research that hasn’t been done,” says Diana Zuckerman, PhD, president of the NRCWF.

The implants are used for women seeking cosmetic breast enhancement and breast cancer patients and others needing reconstruction after mastectomies. Concerns over ruptures and the possible health effects of silicone leakage into the body had kept silicone implants off the cosmetic surgery market.

Learn More about Breast Implants and Safety

Split Committee

Last April, an FDA advisory panel voted 5 to 4 to reject Inamed’s bid to sell silicone implants, citing a lack of long-term safety data. The next day the panel voted 7 to 2 to allow Mentor to sell its implant, which appeared to be more durable and less likely to rupture.

Inamed's study showed that 5 percent of women with the implants experienced ruptures within three years of surgery. Company projections concluded that 14 percent of the implants could be expected to break after 10 years of use, but patients were not actually followed for that period of time.

Inamed officials say that they could not link any of the ruptures in their study to serious health effects and instead only found an increased likelihood of local symptoms like pain and breast hardness around broken implants.

But experts at the time criticized the company for not conducting long-term safety trials. An FDA analysis projected that as many as 93 percent of women could experience ruptures after 10 years of use.

Susan Wood, PhD, former director of the FDA’s office of women’s health, says companies have not studied the implants for longer time periods or in an adequate number of minority women.

“There is still such a lack of data in a very real and concrete way,” she says. Wood resigned from the FDA in August to protest the agency’s failure to approve the emergency contraceptive pill Plan B for over-the-counter use.

FDA Panel Sets Strict Conditions for Silicone Implants

Safety Questions Linger

Thousands of women have blamed leaking silicone implants for a variety of health problems, including autoimmune diseases, connective tissue disorders, and cancers.

Mentor implants showed a lower rupture rate, and a small, nine-year study of women in Britain helped convince experts to recommend approval under the condition that the company monitor women closely after surgery.

Inamed conducted a 2003 study of 250 women who got the implants for post-mastectomy reconstruction. But Friday’s report complained that only a fraction of the women were studied using mammography to pick up small leakages that make up the vast majority of implant ruptures.

“There’s practically nothing on breast cancer patients, and we think that’s a terrible loss,” Zuckerman says.

Last summer, the agency issued statements on “approvable” letters to implant makers Inamed Corp. and Mentor Corp. The letters require the companies to meet certain, undisclosed conditions before marketing is allowed.

Silicone Breast Implants Near Approval

Companies’ Positions

Inamed did not respond to calls seeking comment. In April, Patricia Walker, MD, the company's executive vice president for research and development, told the advisory panel, “Our data has shown no systemic illness, no connective tissue diseases over and above what you would expect in the general population.”

In a statement, Mentor would not comment on the conditions FDA has laid out for its products’ approval but says it “continues to work closely with the FDA to address the conditions outlined in the FDA's approvable letter.”

“Mentor believes the advisory panel evaluated the data with rigor and made their recommendation of “approvable” based on the scientific merit of the studies included in the pre-market application,” the company stated.

A 1999 Institute of Medicine study declared no connection between the implants and systemic diseases, though that same year former implant maker Dow Corning agreed to pay $3.2 billion to settle claims that its products sickened patients.

An FDA spokesperson says that the agency does not comment on pending product applications.

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By Todd Zwillich, reviewed by Louise Chang, MD

SOURCES: “Decisions in the Dark: The FDA, Breast Cancer Survivors, and Silicone Implants.” National Research Center for Women and Families, Feb. 3, 2006. FDA Statements on “Approvable” letter to Mentor Corp, July 28, 2005. FDA Statements on “Approvable” letter to Inamed Corp, Sept. 21, 2005. Diana Zuckerman, PhD, president, National Research Center for Women and Families. Susan Wood, PhD, former director, FDA office of women’s health. Patricia Walker, MD, vice president, research and development, Inamed Corp. FDA. Statement, Mentor Corp, Feb. 3, 2006.