Hip and knee implantations among patients with osteoarthritis and risk of cancer: A record-linkage study from Denmark

A nationwide cohort study of hip and knee replacement patients in Denmark w as undertaken to assess any carcinogenic potential of these implants. A coh ort of 22,997 osteoarthritis patients who received hip replacements and of 4,771 osteoarthritis patients who received knee replacements during the per iod 1977 through 1989 were identified using the nationwide Danish Hospital Discharge Registry. These patients were followed for cancer occurrence thro ugh 1993, using the Danish Cancer Registry. There was no overall excess of cancer in either the hip implant cohort [standardized incidence ratio (SIR) = 0.94; 95% confidence interval (CI) = 0.91-0.98] or the knee implant coho rt (SIR = 0.97; 95% CI = 0.89-1.06). The risk reduction in both groups of p atients reflected for the most part reduced risks for cancers of the respir atory system and the digestive tract, particularly stomach cancer (SIR = 0. 69; 95% CI = 0.50-0.81 for hip replacement patients; SIR = 0.46; 95% CI = 0 .20-0.91 for knee replacement patients). Elevated risks were observed for m elanoma of the skin in both groups of patients. There was no clear excess r isk for lymphohematopoietic cancers or malignant neoplasms of the bone or c onnective tissue among implant patients in either implant group. Contrary t o an earlier study in Sweden, we did not find an excess risk for kidney or prostate cancers. In summary, these nationwide results indicate no overall cancer hazard among hip and knee implant patients, but limited follow-up wa rrants continued surveillance of individuals undergoing these increasingly common surgical procedures. (C) 1999 Wiley-Liss, Inc.