TUESDAY, April 18, 2006 (HealthDay News) -- Adding a new twist to the debate over the safety of silicone breast implants, a large Swedish study has found no evidence the implants raise women's risk of breast cancer.
The industry-funded study, which followed nearly 3,500 women for as long as 37 years, is notable because of its size and its longevity.
"Women with silicone breast implants should feel reassured," said study author Joseph McLaughlin, president of the International Epidemiology Institute, in Rockville, Md.
Silicone breast implants, long the focus of controversy, were banned in the United States in 1992 for cosmetic purposes, with some exceptions, amid concerns that leaks could cause a variety of diseases, including immune system disorders, arthritis, lupus and cancer. Tens of thousands of women filed suit against the implant manufacturers, which paid out billions in claims.
The debate has continued, with some studies finding no evidence that leakage from the implants causes systemic disease. Meanwhile, the U.S. Food and Drug Administration has been moving toward allowing silicone implants back on the market as an alternative to saline implants, which doctors say aren't always ideal. Some U.S. politicians and women's groups have expressed dismay that the government might allow use of silicone implants again.
In the new study, American researchers examined a Swedish database of 3,486 women who received breast implants for cosmetic reasons between 1965 and 1993. The study followed the women until the end of 2002, an average of 18.4 years after they received the implants.
The findings appear in the April 19 issue of the Journal of the National Cancer Institute.
Only 53 of the women developed breast cancer, compared to 71.9 cases that would have been expected in the general population. There were 180 total cancers in women with the breast implants, slightly fewer than the 193.1 that would have been expected.
The researchers speculated that the women had fewer cases of breast cancer because they're thinner, had more children and had their first children at a younger age, on average. (Excess weight, childlessness and older age at first birth all raise the risk of breast cancer.)
The women who received breast implants were more likely to develop lung cancer than other women: 20 developed it, compared to the 9.1 that would have been expected to have it. The researchers think this is because the Swedish women with implants were more likely to smoke.
Dow Corning, a manufacturer of breast implants, paid for the study. But McLaughlin said the study authors had "complete intellectual freedom."
However, one expert questioned the connection.
"They have this financial vested interest, which we all know can influence things," said Diana Zuckerman, president of the National Research Center for Women and Families. "They're trying to put this to rest and say, 'See we knew it, this product is perfectly safe.'"
"The jury is still out" on the safety of breast implants, said Zuckerman, pointing to a new federally funded study that found that women with breast implants have a higher rate of suicide. She added that it's not entirely clear that smoking explains the higher rate of lung cancer in implant patients.
Dr. Roxanne Guy, president-elect of the American Society of Plastic Surgeons, said she expects the FDA to make a final decision about the sale of silicone breast implants later this year.
In some cases, silicone implants are a better option than saline implants, especially if breast tissue is thin and can't support the saline implant as effectively, she said. "There are many patients in which nothing is going to work as well as a silicone implant."
The U.S. Food and Drug Administration has more on breast implants.