Medicine Balls Special: Metal Hips, Cancer Scares and the British Medical Journal
To commercially damage any product, however inadvertently, all you have to do is link it with cancer in the public mind. The ensuing panic benefits lawyers and journalists, but it only helps the public if the risks are substantial and somewhere near proven. In March, a group of angry orthopaedic surgeons contacted the Eye to complain about the link of Metal on Metal (MoM) hips to cancer in the March 3rd edition of the British Medical Journal1 2, and a BMJ-Newsnight ‘special report’ on February 28th 3. The cancer link was picked up in the Sunday Times 4 on March 4th and fuelled an ongoing cancer scare in patients with MoM hips, and patients who weren’t sure what hip they had.
As for patients considering a new hip, who would now choose an MoM when a source as credible as the BMJ states there are ‘substantial concerns about the increased risk of cancer’? But there is no good evidence showing MoM hips cause cancer. Bristol University, one of the leading research centres looking at this told the Eye: ‘It is far too early to make any conclusions’ about any link with MoM hips and cancer. And although cancer scares are regular occurrences in the media, you’d expect better from the BMJ (motto ‘helping doctors make better decisions.’)
This was the second cancer scare orthopaedic clinics had to deal with in only a month. On February 5th, the Telegraph ran a story linking MoM hips to bladder cancer 5, based on unpublished research from Dr Patrick Case and colleagues in Bristol. Because the research was unpublished, NHS staff dealing with anxious callers had no access to any reliable information to give to patients. When the Sunday Times later became interested, Dr Case – a Consultant Senior Lecturer at the University of Bristol – wrote a desperate e mail to colleagues: ‘I have told this journalist that our study does NOT provide the first clinical evidence linking metal-on-metal hip implants to an increased risk of cancer. Our paper is not yet written and it will not conclude this. The journalist has told me that he will change his story. I have warned him of a public scare and have reminded him of the MMR panic.’ The Sunday Times (March 4th) duly lead with the front page headline: ‘Research links hip implants to cancer’.
The research has still not been published and may never be. Of 80 patients studied, one had bladder cancer, he’d only had an MoM hip in for a short time but he was a heavy smoker (a far more likely cause). To make matters worse, a BMJ-Newsnight investigation on February 28th gave another plug to the Bristol scare. ‘We understand that on Thursday, research will be presented looking at the risks of bladder cancer in these (MoM hip) patients.’ The BMJ and Newsnight should have been aware of the widespread panic this ‘non story’ had already caused. The University of Bristol states that no one from the BMJ or Newsnight contacted them prior to broadcast, and that there is, as yet, no clinical evidence linking bladder cancer and MoM hips. And the BMJ had far more substantial research due for publication from the National Joint Registry that was much less alarmist.
On April 3rd, the BMJ published the paper 6 which concluded: ‘In a large representative sample there was no association between metal-on-metal hip replacements and increased incidence of cancer in the first seven years after hip replacement.’ And ‘the one year incidence of cancer after total hip replacement is lower than that observed in the general population.’ But by that stage, the damage in the public mind had been done. As a lawyer from the London firm Leigh Day – which specialises in MoM hip litigation – told the Sunday Times: “The fact that you’ve now got a study which demonstrates that there may be cell changes is very significant.” And doubtless many more clients were flushed out by the scare.
There are failure problems with some types of MoM hip. The DePuy ASR range was removed from the market in 2010 and stemmed MOM implants are failing at much higher rates than other types, particularly those with larger head sizes and those implanted in women, in whom failure rates are up to four-times higher. But other types, such as the Birmingham Hip Resurfacing (which MD would choose for himself), have an excellent track record over 15 years, particularly in large, active men, and the last thing they need is an unsubstantiated cancer scare.
The theory linking MoM hips with cancer is that the metal surfaces of the cup and ball joint wear, producing particles of chromium and cobalt that enter the tissues and blood stream and could one day lead to cancer. Some of the newer MoM hips release more chromium and cobalt than previous models. Whether this is just a marker of wear and tear in the hip, or whether it could lead to distant disease or widespread poisoning has yet to be established. After 7 years of follow up on these models, no proof has been found.
The BMJ is part of a worthy campaign to improve the regulation of medical devices. New rules are currently being drawn up by the European Commission to give the public access to details of the clinical research about all devices and implants, and their safety record. But the BMJ’s high profile campaigning has to tempered with scientific balance. The March 3rd issue seemed to damn all types of MoM implant. ‘The risks of metal on metal hip implants’ had a bold green headline on the cover and the story – and link with Newsnight– was heavily trailed by the BMJ publicity department. The editor’s choice was headlined ‘Serious risks of metal on metal hip implants’ and the only two features in the journal were an investigation titled ‘Hip implants: how safe is metal on metal?’ and an adjacent commentary taking a very similar line: ‘Ongoing problems with metal-on-metal hip implants.’ The coverage was overwhelming negative with no balancing article on, say, the success of the Birmingham hip.
The large print summary in the first BMJ article claimed that ‘hundreds of thousands of patients may have been exposed to toxic substances after being implanted with potentially dangerous hip implants’ and the second opened with ‘substantial concerns currently exist’ about ‘newer (MoM) hip implants and increased risk of cancer.’ MD asked some of the authors to provide details of any patient known to have cancer or poisoning from an MoM implant. There were no cancer patients to be found, and a few possible metal ion poisonings in Alaska. The best we can currently say is more research is needed (see University of Bristol statement below). Far from sounding like the balanced voice of British medicine, parts of March 3rd issue read like a lawyers’ press release. An internet search of ‘hip lawyer bmj’ reveals pages of citations on legal websites in the US and UK, many feeding on the credibility of the BMJ.
The BMJ did at least disclose that one of its expert authors, David Langton, is also an expert witness in a class action lawsuit in the United States in relation to the DePuy ASR MoM implant. But it chose not to declare that he is in a relationship with the BMJ’s investigations’ editor, Deborah Cohen, who wrote the other article and presented the Newsnight film, and who had declared the relationship to the BMJ. Dr Cohen introduced Mr Langton to the other authors, but the BMJ says there is no financial relationship between them, so it did not need to be declared to its readers. Many orthopaedic surgeons and hip manufacturers who were aware of the relationship have other views and in MD’s opinion, the BMJ should either have declared it or simply removed one of these authors from the investigation.
What is certain is that the hip-cancer scare caused considerable short-term distress for patients and a large increase in workload for NHS staff dealing with calls and inquiries. The long term fear is that patients will shun a proven prosthesis such as the Birmingham hip for a less tested variety, and that those with existing MoM hips will ask them to be removed because of the cancer scare when the known risks of revision are far greater than the unproven risk of cancer. In June the BMJ quietly published a paper on line (with no press release or Newsnight film) that concluded 7‘Compared with uncemented and cemented total hip replacements, (the) Birmingham hip has a significantly lower risk of death in men of all ages.’
The BMJ has admitted to the Eye that the evidence linking hip replacements and cancer is ‘sparse’, and for those who read the offending articles in their entirety, this point is made. However, the alarmist headlines, press release and accompanying film had a predictable effect in whipping up anxiety and legal interest. And once a health scare is out of the bottle, as the Eye well knows following its involvement with MMR, er…. it’s extremely hard to put back in.
7 BMJ 2012;344:e3319
Statement from University of Bristol re: Sunday Times article –
Research links hip implants to cancer
Researchers at the University of Bristol presented a paper to the Hip Society last week [Thursday 1 March] about an unpublished study on metal-on-metal hip implants.
Contrary to media reports, the study will NOT provide the first clinical evidence linking metal-on-metal hip implants to an increased risk of cancer.
The paper, which has not yet been peer-reviewed when published, is expected to conclude that metal-on-metal hip implants is an important subject and a larger study involving several centres will need to be conducted to show whether or not there is a risk of cancer from metal-on-metal hip implants.
Patients who are concerned about their metal-on-metal hip implants should contact the hospital that carried out the procedure for advice.