FDA Reviews Silicone Gel Mouse Study
FDA has received inquiries about results of a study published in the July 20 Journal of the National Cancer Institute which show that silicone gel induces a rare form of cancer in strains of laboratory mice. The following can be used to answer questions.
In the study, silicone gel was injected into the abdomen of two strains of mice that are good experimental models for a rare type of cancer called plasmacytoma. Plasmacytomas in mice are similar to a rare blood cell cancer in humans called multiple myeloma.
The relevance of the study to women with silicone gel-filled breast implants is not yet known. FDA is aware of a few cases of women with breast implants who have developed multiple myeloma.However, there is no evidence at this point that women with the implants are any more susceptible to this disease than other women. Since multiple myeloma occurs throughout the population, some cases are expected to develop in women both with and without implants. Multiple myeloma is a rare disease. Approximately four new cases occur annually in 100,000 persons in the United States. Based on these rates and the number of women with implants, over the past six years it would be expected that 155 cases of multiple myeloma would have occurred in women with breast implants, whether they had the implants or not.
Signs and symptoms of muultiple myeloma include weakness and fatigue, bone pain, kidney failure, recurrent bacterial infections and anemia. For some patients, weakness and fatigue may be the primary symptoms. To help provide answers to the questions of whether breast implants can increase the risk of multiple myeloma, researchers are asking physicians to report cases of the disease found in their breast implant patients. Physicians aware of new cases are encouraged to report them to FDA through the MedWatch program at 1-800-FDA-1088.
The results of the study do not change FDA's previous advice to women with breast implants. Women should be alert for signs of problems and see their doctors if these occur. Women who are not having problems need not have their implants removed.
The study also does not change FDA's position on the ongoing clinical trials of silicone gel-filled breast implants. These studies have been restricted to women undergoing breast reconstruction for medical reasons such as breast cancer. As part of the informed consent requirements of the studies, participants are warned about the risks of the implants, including the uncertainty about possible immunologic and carcinogenic effects. The woman and her doctor must weigh the potential benefits of the breast reconstruction against the known and unknown risks of the implants.