A long- running study has found that while women with breast implants are not at increased risk for most cancers, they appear to suffer higher rates of lung and brain cancer than other plastic surgery patients, researchers at the National Cancer Institute said today. The study demonstrated only a link between implants and the two types of cancer, not a cause-and- effect relationship, and its significance is unclear, said the lead author, Dr. Louise A. Brinton, chief of the cancer institute’s environmental epidemiology branch. “What the study showed is no difference for most of the cancer sites, which I think is good news,” Dr. Brinton said. “And for the few sites which we did find differences, we have no ready explanation. So I would not want to alarm women on the basis of one study.” Nonetheless, the results are likely to inflame the debate over the safety of breast implants. “I see this as a warning,” said Dr. Diana Zuckerman, director of the National Center for Policy Research for Women and Families, who served on the study’s scientific advisory panel.
“You can’t draw a conclusion from these studies, even though they are very well designed, very solid,” said Dr. Zuckerman, who nonetheless added, “I think this is very alarming.” Dr. Brinton’s group identified nearly 13,500 women who received breast implants before 1989 and followed them for an average of 13 years. The women were compared with a control group of 4,000 other plastic surgery patients and with the general population. The study results, which focused on a comparison between the breast implant patients and the plastic surgery control group, were based on questionnaires completed by 7,500 of the women, as well as medical records and, in some cases, death certificates. The women’s average age when they received their implants was 34, and all had implants for at least eight years. Most had silicone implants, which the Food and Drug Administration removed from the market in 1992; about 10 percent had saline implants.
The researchers found that the type of implant made no difference in a woman’s cancer risk. Results from the study appear this month in two medical journals: Epidemiology, and Annals of Epidemiology. It found that women in the implant group were three times as likely to die of diseases of the respiratory tract, primarily lung cancer, as the women in the plastic surgery control group, and twice as likely to die of brain cancer. A separate analysis of the number of malignancies, as opposed to deaths, also found higher rates of lung and brain cancer in women with implants. Previous research has suggested that women with implants may be at increased risk for lung problems, and some experts have theorized that silicone gel, which coats even the saline implants, migrates to the lung. But Dr. Brinton said she could not rule out smoking as a factor. In her study, the implant patients and the women who had had other plastic surgery reported the same rates of smoking. But most of the lung cancer information was gleaned from death certificates, so it was impossible for researchers to know whether those women smoked. “We couldn’t fully account for smoking differences,” Dr. Brinton said. As to the brain cancer finding, she said, researchers do not have a plausible explanation for it, and so further research is necessary.