The Food and Drug Administration is skeptical and asked its scientific advisers Tuesday to recommend whether the California company has provided enough evidence to allow the controversial medical devices back on the market.
It's such an emotionally charged issue that on Monday, the FDA took the extraordinary step of devoting a daylong hearing from the public — more than 150 people — on whether to lift restrictions that since 1992 have limited silicone-gel implants to women in special research studies.
Dozens of women, many in tears, told of serious pain and other symptoms that they blame on silicone leaking through their bodies.
"I was young and naive when I received implants. I didn't have the foresight to see that my health is much more important than my breast size," said a tearful Karen Antolick of Columbus, Miss.
Inamed urged the FDA's advisers not to be swayed by the emotion.
"As horrible and heartbreaking as these testimonials are, we must rely on science," said Dr. Patricia Walker, Inamed's chief scientific officer.
The implants were banned back in 1992, after thousands of women complained they ruptured and caused immune system diseases, joint problems and even suicides. But medical studies have never been able to prove the link, and now only women who have had breast cancer can opt for silicone, reports CBS News Correspondent Elizabeth Kaledin.
Last year the FDA rejected Inamed's attempt to resume widespread sales because how often the devices break — requiring more surgery to remove or replace — and the local health consequences that result are still in question.
About 14 percent of implants will break within 10 years, Inamed officials told the FDA panel Tuesday, an estimate derived from a study of 940 patients tracked for three or four years.
In just one in 20,000 implants will silicone gel ooze beyond the immediate implant area, the company contended. In its study, women whose implants broke reported no more complications than women with intact implants.
Preliminary FDA analyses, in contrast, suggest up to three-quarters of implants will break within a decade.
Why the difference? The FDA assumes that, like many medical devices, as an implant ages it will become more fragile. Inamed's estimate assumes the same proportion of implants will break each year — and it blames most of the breakage on surgeon-caused damage at the time of implantation that essentially weakens the device.
That makes no sense, responded FDA adviser Stephen Li, a device-testing expert from Sarasota, Fla. "The odds of creating a series of nicks and cuts ... and it just so happens the same number of them break every year, it's almost fantastic," he said.
But Inamed argues that salt water-filled implants sold today don't break at a faster rate over time, and that gel implants are just as durable.
Another FDA adviser, New York dermatologist Dr. Amy Newberger, questioned how Inamed was sure that the new, stickier gel didn't leak beyond the breast. She cited a recently published study from the Armed Forces Institute of Pathology that found silicone in implant recipients' lymph nodes, a gateway to the rest of the body.
Inamed officials dismissed that study, saying silicone also is present in numerous other products, from plastics to toothpaste that could be the source.
"The issue here is an issue of choice. American women are very, very smart and I think they should be given the option to choose what kind of implant they want," said plastic surgeon Dr. Robert Rey on CBS News' The Early Show.
"What we're talking about is a risk of benefit to ratio," responded Dr. Edward Melmed, a plastic surgeonon The Early Show. "The risk is that you're going to put an implant into possibly 16 or 18-year-old girls. In their lifetime they're going to be faced with the probability of four to five operations."
The FDA's advisers were scheduled to vote on whether Inamed has satisfied federal requirements to sell. The agency isn't bound by its advisers' recommendations — indeed, it rejected a 2003 vote from this same panel that narrowly recommended the implants' return. FDA officials haven't indicated how quickly they will decide.
On Wednesday, the panel will consider similar silicone implants made by Inamed competitor Mentor Corp., also of Santa Barbara, Calif.