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Cancer decision aid? I smell a very large rat

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You’ve heard of dogs sniffing out cancer? Well now it seems rats are even better at it; or at least the Department of Health think so.

According to the Sunday Times, our masters in Government are so convinced of the benefits of these murine friends that they plan to send one to every GP in the country in order to improve our woefully inadequate skills at detecting, diagnosing and destroying cancer.

Don’t worry if yours hasn’t arrived yet - neither has mine, and the longer this particular pest remains absent the better, as it is sure to bring with it the plague of overmedicalisation.

The ‘rat’ in question is not the furry, long-tailed variety, but a Risk Assessment Tool (RAT). It is designed as a decision aid, a prompt to trigger our thoughts towards cancer so that we don’t ever miss it: enter a few symptom codes on the patient record and it will do the maths in the background, incorporating risk factors such as the patient’s age, smoking status, BMI and family history and then a helpful message will pop up onto our screens, informing us of the risk that the person in front of us has cancer.

Remember the Microsoft Office Assistant? That irritating paperclip that used to appear at the most unhelpful moments and say something like ‘it looks like you are writing a letter…’? Remember how you used to want to swat it away, joyously found out how to close it, but then it kept coming back? This will be worse.

The RAT won’t just be trying to help you. Instead, it will be filling the panic section of your brain with the fear of missing something, and the worry of being criticised - sued even - for going with your gut instinct when the RAT is telling you something different.

As GPs we are used to dealing with uncertainty, with the responsibility of dealing with 40, 50, 60 clinical decisions a day. We are used to interpreting risk calculators for future risks of events like a stroke. We are not used to a computer algorithm throwing risk statistics at us in the here and now to aid our diagnoses. What risk should we worry about? 10%? 5%? I’m not sure I want one in 20 of my patients coming back with a missed diagnosis of cancer, maybe I’ll play safe and go with 1%.

Still, the Department of Health wouldn’t invest in such a system if it hadn’t been properly tested, would they? Of course not. There’s been a trial - not a very long one, and not the most robust form of trial either - a before-and-after analysis rather than anything randomised. One trial only, of course, since we don’t want to delay getting a policy into practice on the basis of that awkward insistence of scientists that study findings ought to be validated by being independently reproducible.

The study found, inevitably, there were more referrals, more chest x-rays and colonoscopies (the trial looked just at lung and bowel cancer) and a few more cancers - 10 bowel cancers, maybe, but we don’t know if this was just a chance finding since there’s no statistical analysis. 47 more lung cancers, but only 5 of these were at stage 1 or 2 where the earlier detection might have made a difference.

Did the RAT improve mortality, or would these cancers have been picked up anyway? We have no idea. What about the subgroup where the GP felt the RAT made them refer when they wouldn’t usually refer? Or not refer when they usually would? The study didn’t look at that. What was the effect of all these extra two-week rule referrals on the wait time for routine referrals? Your guess is as good as mine.

And the bottom line - was the use of the RAT cost-effective? When you add to the IT costs the cost of all those extra referrals, tests and treatment, is this aid to GP diagnostic skills a good use of resources?

There were 270 extra colonoscopies in the study, which evaluated less than one percent of GPs for six months. This would equate to around 54,000 nationally per annum. At £446 a go, I work that out as £24m on colonoscopies alone.

You’d think someone would have to justify that expenditure, but the study authors themselves say that ‘It will require health-economic analyses to determine if such a yield is cost-effective.’ In other words, no-one has yet looked at the sums.

Before I sink into despair, however, or throw away my computer and decide to go back to paper notes in my wish to avoid the arrival of my own personal RAT, I have one glimmer of hope: in order to make this happen, the Government will have to roll out a national IT programme compatible with all GP computer systems.

Now when was the last time that ever happened?

Dr Martin Brunet is a GP in Guildford and programme director of the Guildford GPVTS. You can tweet him @DocMartin68. 

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