No higher cancer risk from hip prostheses

5 November 2019

Discussion is under way in the EU on classifying cobalt, which is included in orthopaedic implants, as a potential carcinogen. A group of researchers at Uppsala University have used several different nationwide registers to explore the association, if any, between cancer and hip prostheses. In a newly published study, they found that there is no generally increased risk of cancer after total hip arthroplasty (THA).

Can you get cancer from a hip implant? The question is not just picked out of a hat, since hip prostheses contain metal ions and other chemical substances that are said to be capable of causing cancer. Previous studies on the risk of cancer after THA are contradictory: some researchers have found an increased risk of cancer, while others have not.

Help from nationwide registers

Uppsala University researchers have now used several nationwide registers, including the Swedish Hip Arthroplasty Register and the Swedish Cancer Register, to evaluate the risk of developing cancer after insertion of a hip prosthesis. Over 100,000 patients who had THA owing to joint failure were compared with over 500,000 control subjects without prostheses. The two groups’ cancer rates were evaluated after an average observation period of 14 years.

The patients given cemented hip prostheses had a slightly lower risk of developing cancer than the control subjects (hazard ratio 0.97; confidence interval 0.95–0.99). The only cancer form with a statistically significant risk increase among the hip replacement patients was malignant melanoma, but the risk increase was relatively small. Other cancers, such as various forms of blood cancer and lung cancer, were less common in the THA patients than among the control subjects. The researchers also found a reduced risk of cancer among the patients with hip prostheses when results for women and men were analysed separately, when only patients who were followed up for at least five years post-THA were examined and in patients with cementless prostheses.

Reassuring information

“So in this study on a very large, well-defined population, with long follow-up, no increased risk of cancer after THA was found. These reassuring facts can be included in the pre-operative information given to arthrosis patients according to the guidelines. This is particularly important these days, when a new EU guideline requires THA patients to be informed that they’ve been exposed to potentially carcinogenic substances,” says Nils Hailer, Professor at Uppsala University’s Department of Surgical Sciences and Consultant at Uppsala University Hospital.

Publication

Nils P. Hailer, Anne Garland, Max Gordon, Johan Kärrholm, Olof Sköldenberg, Niclas Eriksson, Hans Garmo, Lars Holmberg (2019). No generally increased risk of cancer after total hip arthroplasty performed due to osteoarthritis, International Journal of Cancer, DOI: 10.1002/ijc.32711.

Researchers from Karolinska Institutet, University of Gothenburg, Uppsala Clinical Research Center and King’s College London also contributed to the study.