Incidence of breast and other cancers among Finnish women with cosmetic breast implants, 1970-1999.

Epidemiologic evidence does not point to a carcinogenic effect of silicone implants on the breast, and evidence for or against a carcinogenic effect at sites other than the breast is limited. To examine subsequent cancer risk among women with cosmetic breast implants, we conducted a cohort study of 2171 women in Finland identified from operation diaries of major hospitals and private clinics, 1970-1999. The nationwide population and health outcome registries in Finland were used to trace these women for cancer incidence through 1999. Standard statistical techniques were used to compute expected values based on general population rates. The measure of risk was taken as the ratio of observed to expected cancers, that is, the standardized incidence ratio (SIR) and its 95% confidence interval (CI). Among the 2171 women with cosmetic breast implants, 30 developed cancer against 33.7 expected (SIR = 0.9,95% CI = 0.6-1.3). There was no evidence for an increase in breast cancer risk (SIR 0.5, 95% CI, 0.2-1.0), even among those followed for more than 10 years (2 observed, 4.6 expected). Stage at breast cancer diagnosis did not differ from that expected nor did incidence of any other cancer. Although hindered by small numbers, the consistency of our results with those of other Nordic studies leads us to conclude that cosmetic breast implants are not a cause of cancer and that they do not appear to delay the detection of breast cancers.