Cancer occurrence after cosmetic breast implantation in Denmark

Most studies on cancer incidence after breast implantation have focused on breast cancer, while the risk of cancers at other sites has been less well investigated. We examined cancer incidence among 1,653 women who underwent cosmetic breast implant surgery at private clinics of plastic surgery in Denmark and 1,736 women attending the same clinics for other reasons during the period 1973-1995. Furthermore, we updated previously reported results among 1,114 women who received implants for cosmetic indications at public hospitals. All women were followed for cancer through the Danish Cancer Registry. In comparison with the general female population, the overall standardized incidence ratio (SIR) for cancer among women who received implants in private clinics was 1.65 [95% confidence interval (CI) = 1.17-2.27]. This elevated SIR reflected increased incidence ratios for almost all major cancer sites; however, only for non-melanoma skin cancer was there an excess of more than 2 cases. No significant excess of cancer was observed among women who received implants in public hospitals (SIR = 1.10, 95% CI = 0.76-1.52) or among women attending the private clinics for other problems (SIR = 1.10, 95% CI = 0.78-1.52). The SIRs for breast cancer after breast implantation were 1.1 (95% CI = 0.5-2.2) among private clinic patients and 0.9 (95% CI = 0.4-1.7) among public hospital patients. The overall findings of these 2 implant cohorts and results from other investigations suggest that cancer risk is probably not increased among women receiving cosmetic breast implants. The inconsistent results for private clinics and public hospitals are likely related to selection bias and confounding among the private clinic patients, but our data did not permit exploration of these possibilities. Further research into the determinants of these inconsistencies is warranted.