Possible breakage of the implants and the health impact of the silicone leaking into a woman's body are among the contentious issues surrounding the decision.

The implants were banned in 1992, after being implicated in a host of health problems, and have been available only to participants in research studies since that time. Fear that they might cause cancer or lupus has been quelled by the research findings, but other potential complications continue to fuel controversy.

Scar tissue may form around the implants, for example, which can become a painful condition. In some cases, women have to undergo surgery to remove defective implants.

Chairman Bucked Committee Recommendation

In October 2003, the General And Plastic Surgery Devices Advisory Panel voted 9 to 6 in favor of approving silicone gel implants, but the committee chairman independently advised the FDA to reject the recommendation, citing long-term safety issues. The FDA declined approval at that time and requested more information.

Possible breakage of the implants and the health impact of the silicone leaking into a woman's body are among the contentious issues surrounding the decision.

Ruptured implants were implicated as the cause of many connective-tissue and autoimmune diseases, such as multiple sclerosis,following thousands of cases of breakage in the late 80s and early 90s.

Competing Manufacturers to Present Studies

Mentor Corporation, an international medical products supplier, will present data from a silicone gel breast implant study in support of its pre-market approval (PMA) application on April 13, the day the panel will vote on the issue and make its recommendation to the FDA.

Mentor's Core Gel Study followed 1,007 women who were implanted with silicone gel-filled breast implants, either for augmentation, reconstruction or revision surgery.

The data submitted to the FDA includes information from the 3-year follow-up period, as well as longer-term clinical data specific to the integrity of Mentor's silicone gel-filled breast implants.

Inamed Corp. also has provided the FDA with new data on its silicone breast implants.

However, US regulatory staff indicate in the reports made public Wednesday that both the Mentor and Inamed data are of "limited value" in assessing the risk of ruptures.