Friday, 5 October 2012

Interpreting QCancer scores


QCancer and referral
 
Early diagnosis of cancer is a real Hot Topic, and there has been a huge ammount of interest on our Autumn courses in using the QCancer tools to aid patient assessment. These tools should  obviously only be used to aid (and not supplant) clinical assessment by a patient’s GP, but the most frequently asked question has been: is there a recommended referral threshold for the Qcancer risk tool?

So, we asked Prof. Julia Hippisley-Cox herself and this is her reply:

‘In terms of the threshold, there is no absolute threshold currently – my view is that the tool quantifies risk in a way that helps the GP and patient make an assessment of probabilities. For some people, I risk of 2% will seem high and they will want full investigation. For others they will concentrate on the 98% risk that they don’t have cancer X. The assessment also needs to take account of the risks associated with investigation  - for lung cancer, then the risk of an adverse event to a CXR is pretty low but for other tests [eg endoscopic ultrasound scan of the pancreas] then the discomfort of the procedure and risk of perforation might be higher.

That said, we have looked at risk thresholds in each of the papers and there is a table of sensitivity, specificity etc at different thresholds. I tend to think a threshold of 2% overall is reasonable rule of thumb (NB this is the referral threshold recommended by the National Cancer Action Team when using the RAT tool for colorectal and lung cancer, Simon). I suspect this is something the new NICE guidelines may address more fully. I am going to present to them in December.

We have got a new paper coming out [no publication date yet] which combines all the cancers into one tool and gives a global cancer risk and then apportions the risk of each cancer. I will let you know once this is available. In the meantime, there are some slides in the public section of the download page of www.qresearch.org which will give you an idea.’

 
NB disclaimer: These tools are designed to assess the risk of a patient having an existing, but as yet undiagnosed, cancer. The calculators take account of the patient's age, sex, family history, medical history and symptoms. The tools are intended to be used by doctors in a health care setting.

 Thanks Julia! Simon

 

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