(Embargoed) CHAPEL HILL - The largest, most comprehensive study done to date of the possible link between silicone breast implants and connective tissue diseases has found no evidence that the implants impair women's health.
Reported in Thursday's issue (March 16) of the New England Journal of Medicine, the University of North Carolina at Chapel Hill research could uncover no relation between the medical devices and such illnesses as rheumatoid arthritis, lupus erythematosus, scleroderma or other systemic conditions.
"This is an issue that has caused considerable and persistent debate in medical and legal circles," said Dr. Esther C. Janowsky, adjunct assistant professor at the UNC-CH School of Public Health and lead author of the paper. "The goal of our research was to look at the question of possible harm from silicone breast implants using several different approaches while at the same time including as many studies as possible. Our conclusion is consistent with earlier work indicating no relationship."
Other authors of the New England Journal article are Drs. Lawrence L. Kupper, Alumni Distinguished professor of biostatistics, and Barbara S. Hulka, Kenan professor of epidemiology, both also in public health at UNC-CH.
Researchers performed a series of meta-analyses. Meta-analysis involves combining and analyzing information from previous studies and is particularly useful when previous studies have lacked enough subjects to produce a clear result, Janowsky said. Through various computer searches, the UNC-CH team found 757 citations in the world medical literature and reviewed all the potentially relevant work on the effects of silicone breast implants.
The team eventually included information from nine cohort studies, nine case-control studies and two cross-sectional studies that met various standards, including the presence of an internal comparison group and numbers available to create tables for the meta-analyses. Most took place in the United States but also represented investigations in Canada, Australia, the United Kingdom and northern Europe.
Women who had direct injections of any material into their breasts, including silicone, were excluded from the analysis, the physician said. The two studies that included enough information to analyze the effect of how long implants had been in place suggested that the likelihood of any illness did not increase over time. Not enough information was available to assess the effect of implants if they leaked or ruptured while inside women's breasts.
Intensive publicity about suggested adverse health effects of breast implants is likely to have made women with implants more aware of their symptoms and to have resulted in over-reporting of disease among such women as compared with others without implants, the authors wrote.
"On the basis of our meta-analyses, there was no evidence of an association between breast implants in general, or silicone-gel-filled breast implants specifically, and any of the individual connective-tissue diseases, all definite connective tissue diseases combined, or other autoimmune or rheumatic conditions," they said.
"From a public health perspective, breast implants appear to have a minimal effect on the number of women in whom connective tissue diseases develop, and the elimination of implants would not be likely to reduce the incidence of connective tissue diseases," they concluded.
The Administrative Office of the U.S. Courts supported the UNC-CH study, which originally was part of a report by a National Science Panel appointed by Judge Sam C. Pointer Jr. for the federal judiciary. Hulka was a member of the panel. Pointer's goal was to hear from scientists responsible only to the courts and not from paid experts representing either side in suits for damages allegedly caused by silicone implants.
Note: Janowsky, who is in California temporarily, can be reached at (619) 296-4144. After March 17, she can be reached at (919) 942-7941. Hulka's number is (919) 966-7412 until 4 p.m. March 13 and (919) 933-2243 for the rest of the day. Between 3/13 and 3/19, she will be at either (949) 721-2200 (meeting) or (949) 759-0808 (hotel) before returning to Chapel Hill. The panel's full report can be found at http://www.fjc.gov/BREIMLIT/SCIENCE/report.htm.
Journal
New England Journal of Medicine