Does long-term exposure to gel-filled silicone implants increase the risk of relapse after breast cancer?

Background: An increased risk of cancer and autoimmune diseases associated with gel-filled silicone implants, debated by FDA experts since 1991, has given rise to a profusion of literature on the subject. However, such effects have not been adequately investigated in patients with breast cancer. In a previous report we compared 146 breast cancer patients with gel- filled silicone implants for breast reconstruction to 146 control patients in whom no reconstruction had been performed. The observed results were reassuring, as the evolution of the disease after 10 years was better in the reconstruction group than in the control group. We now report the end results of this study with a median follow-up of 13 years after the breast reconstruction (range, 10-20 years). Method: The relative risks of detrimental events were estimated with Cox's Proportional Hazards Model, with stratification according to age at diagnosis. Results: The risks of locoregional recurrences and distant metastasis were significantly lower in the BR group than in the control group. The risks of death, of a second breast cancer and of a second primary cancer at a site other than the breast were not significantly different between the two groups of patients. Conclusion: Long-term follow-up of patients exposed to gel-filled silicone implants confirms the absence of detrimental effects after breast cancer. The power of our study is, however, below that required to detect a very slight increase in the risks studied.