There was a whirlwind of activity in the moments following my diagnosis of chondrosarcoma, a cancer of bone tissue. I spoke to the consultant about surgical options, I shared worries with the clinic nurse, and someone asked me about being involved in a clinical trial.
Since I am the Web Editor for The Institute of Cancer Research, I was keen to find out more about this clinical trial, what the researchers are looking for and why they think I – or at least my left leg – might be able to help. It was explained to me that because my cancer is so rare, hospitals across London had teamed up in order to provide large enough groups of patients to take part in a clinical trial looking for new ways of using an MRI scanner to diagnose chondrosarcoma.
The number of major collaborations between research centres is increasing all the time. As a patient with a rare tumour (which, thankfully, has been removed), I was interested to find that the International Rare Cancers Initiative (IRCI) has published a paper that presents challenges and methods available for conducting collaborative research into rare cancers.
In this case, a rare cancer means ‘any cancer which is diagnosed in fewer than 6 people per 100,000 per year’. Although individually rare, these cancers make up 22% of all diagnosed cancers – more so than any single common cancer. Despite this high collective prevalence of rare cancers, research over the last couple of decades has, understandably, focused on the more common forms of the disease, in order to benefit the greatest number of patients. As a result, treatment for many rare cancers has improved more slowly than for the more common kinds.
Dr Emma Hall, a team leader at the ICR, is one of the authors of the report and I spoke to her about some of the challenges faced with researching rare cancers.
“We dealt with committed researchers from the UK and the rest of the globe – and this is a really good thing! Where we get difficulties is in enrolling a reasonable number of patients to make meaningful, statistically relevant decisions. To do this, we have to conduct international clinical trials – involving many different treatment centres.”
Employing the services of different hospitals brings with it a problem. Many institutions will have their own standards of care for specific rare cancers.
This can be problematic, as Dr Hall explained to me: “Since these are rare cancers, there isn’t much of an evidence base upon which standard treatment practices can be built. When developing a clinical trial, there is often agreement about the key question being asked, but it is difficult to get an agreement on precise details of what the control or treatment arms should be in order to answer this question because standard treatment varies so much.”
Researchers must also agree on an acceptable level of confidence that the data they obtain are the result of a real effect. Most practice-changing clinical trials require large populations of patients in order to produce statistically robust results relating to moderate treatment effects – but these large populations are not available for rare cancers. The report highlights lots of different ways of balancing the requirement for statistically meaningful results with the limited number of patients available for these trials. The approach taken by Dr Hall – with colleagues including Dr Steve Nicholson, the UK Clinical Lead for the IRCI penile cancer group and Professor Lucinda Billingham from the University of Birmingham – is called a ‘reverse philosophy’ trial. Instead of recruiting a set number of patients in order to answer a pre-defined question, the team first looked at how many patients they were able to recruit, and then determined whether this would provide sufficient information on which to base treatment decisions in the future.
Dr Hall said: “For the InPACT trial, we looked at how many patients we could recruit over a reasonable length of time. We then used Bayesian methods to determine the probability that the results of this trial might have a clinical impact. For example we could say that, ‘if the data suggest the probability that the new treatment is better than the standard treatment is 80% or more, then we will use this to help shape clinical practice’.”
The authors of the report argue that through careful consideration, early on, of how the trial might affect patients, new treatments for rare cancers could be better developed, tested and approved.
Dr Hall summarised the goals of the IRCI: “Through clinical trials, we are trying to create an evidence base for new treatments for rare cancers, improving outcomes for patients.
“It’s really great that the IRCI has the committed support from groups such as Cancer Research UK, the National Institute for Health Research Cancer Research Network, and the National Cancer Institute in the States, as it means we are more likely to get the number of patients and the financial support required to run these trials – which are often more expensive per patient than other clinical trials since they require participation from many different treatment centres.”
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