Federal health officials said Wednesday they are investigating a possible link between breast implants and a very rare form of cancer, raising new questions about the safety of devices which have been scrutinized for decades.
The cancer, known as anaplastic large cell lymphoma, attacks lymph nodes and the skin and has been reported in the scar tissue which grows around an implant. The Food and Drug Administration is asking doctors to report all cases of the cancer so the agency can better understand the association.
The agency has learned of just 60 cases of the disease worldwide, among the estimated 5 million to 10 million women with breast implants. The agency reviewed the scientific literature going back to 1997 along with information provided by international governments and manufacturers.
Most of the cases were reported after patients sought medical care for pain, lumps, swelling and other problems around the surgical site.
"We are very interested in trying to understand more specifically which patents may be at more risk and which breast implants may present a higher risk," said Dr. William Maisel, FDA's chief scientist for devices, on a call with reporters. The agency saw no difference in cancer rates between patients with saline versus silicone implants. There was also no difference between patients who got the implants for cosmetic reasons versus those who underwent reconstructive surgery after breast cancer.
Because the disease is so rare, FDA researchers suggested the issue may never be completely resolved.
"A definitive study would need to collect data on hundreds of thousands of women for more than 10 years. Even then, causality may not be conclusively established," the agency said.
Still, the FDA said it is working with the American Society of Plastic Surgeons to register patients with the cancer and track them over time.
Breast implants are marketed in the U.S. by Allergan Inc. and Johnson & Johnson's Mentor Corp. Those companies will be required to update the labeling for their products to reflect the cancer reports.
A handful of researchers have published papers on instances of the lymphoma in breast implant patients over the last three years, prompting FDA's review. Some research suggests bits of silicone can leak into skin and lymph node cells, triggering the cancer. Even saline implants include trace amounts of silicone to help them maintain shape.
The lymphoma is an aggressive form of cancer though it is often curable, according to experts. Treatments include radiation, chemotherapy and a bone marrow transplant, if the disease returns.
Reports of the cancer among women with breast implants have been reported anecdotally for years, according to Dr. Jasmine Zain, a lymphoma specialist at New York University's Langone Medical Center.
"We've seen it from time to time over the years, but this is the first time the FDA actually looked at all the case reports and made a statement," Zain said.
The FDA pulled silicone breast implants off the market in 1992, saying manufacturers had not provided medical data showing their safety and effectiveness. At the time, there were worries about a connection to a variety of diseases, including cancer and lupus. Alarming cases of ruptures added to the concern.
But in 2006 the agency returned the implants to the market after most studies failed to find a link between silicone breast implants and disease.
The approval came with conditions, including a requirement that the companies complete 10-year studies on women who have already received the implants to study leaks, as well conduct new decade-long studies of the safety of the devices in 40,000 women.
The FDA said the companies have continued to pursue those studies, though several of them have enrolled less than half of the patients needed to make them statistically useful.
Dr. Diana Zuckerman said the studies "will be completely useless unless the FDA can convince the companies to do more to keep women in their studies." Zuckerman's group, National Research Center for Women & Families, opposed the FDA's decision to reapprove silicone implants.