Patients who have had metal-on-metal hip replacements need not fear that they could develop cancer in the first seven years after surgery because they are no more likely to develop cancer than the general population, although a longer-term study is required, a study published on http://www.bmj.com">bmj.com today claims.
A recent BMJ and BBC Newsnight investigation looked into the potentially high level of toxic metals from failing hip implants which may, in future, affect thousands of people around the world. The investigation also looked at why these hip replacements were allowed despite the risks being known and documented for decades. The BMJ has a large collection of articles about the safety of medical devices which can be found here: http://www.bmj.com/article-clusters.
This study, commissioned by the National Joint Registry of England and Wales and carried out by authors from the Universities of Bristol and Exeter, looks at whether these concerns are valid. The registry contains records of over one million procedures from at least 97% of orthopaedic units. Every year registry data and hospital episode statistics are linked up to check how patients who have had joint replacements are faring.
Results show that the chance of a 60 year old man with moderate health and a metal-on-metal stemmed hip replacement being diagnosed with cancer in the five years following surgery is 6.2%, compared to 6.7% chance with hip replacement using other bearing surfaces. For women, these figures were 4.0% for metal-on-metal stemmed hip replacement and 4.4% for other bearing surfaces. Further results show that the incidence of cancer diagnosis is low after hip replacement and lower than that predicted for the age and sex matched general population.
The authors hope that this study will help clinicians reassure patients that the "risk of cancer for hip replacement patients is relatively low" with no evidence of an increase in cancer associated with metal-on-metal hips. They add though that this only shows results for up to seven years following surgery and the analysis of long-term data is required over the next few decades as some cancers take many years to develop.