A new study has been published by the British Hip Society in Manchester. The report on 71 patients with metal on metal surface hip replacements found abnormalities in bladder cells in 15 patients which are not fully understood. The suggestion is that these cell changes may, in very few patients and over long periods of time, lead to cancer. One patient in this study was found to have early bladder cancer. It is unclear yet whether it was caused by their hip replacement.
A second study has shown no increase in the number of patients presenting with bladder cancers in 723 patients with metal on metal hip replacements compared to 2016 with hip replacements where the ball is metal but the socket is plastic.
Many studies have shown that people with hip replacements tend to live longer than people who do not have them. Roughly 5% of people will have had a diagnosis of cancer before they have a hip replacement and roughly 8% will get cancer afterwards. Not because of the hip replacement but because cancer gets more common as we get older. It is against this background that potential increased risks are assessed.
Population studies have shown that people tend to live longer after a hip replacement and the rates of cancers are different. For instance, people with hip replacements have less lung cancer, less cancer of the stomach, colon but may have slightly more cancer of the bladder and melanoma of the skin.
There are several factors that increase the risk for bladder cancer and the most important is cigarette smoking. There is no verified evidence that having a metal on metal hip replacement increases cancer risk. It has been suggested that it would be unwise to remove joint replacements with the additional risk of surgery just on the possible risk of cancer.