Can we do RCTs of interventions to expedite the diagnosis of symptomatic cancer? And should we?

Richard Neal1

1Bangor University, Bangor, UK

Abstract

Interventions to expedite cancer diagnosis are hard to design and implement. This is because the ‘solution’ to expediting diagnosis is probably multi-factorial and involves change across a number of systems. These include patient awareness and help-seeking behaviour, GP education and clinical practice, GP’s access to – and speed of - diagnostic investigations and specialist opinion, plus secondary care diagnostics. Hence, there are probably only a few simple interventions that may be amenable to trialling; additionally complex interventions are time-consuming and expensive.

We know that patients value investigations for potential cancer even at low risk, but we don’t know whether patients find randomisation to the control arms of diagnostic trials acceptable. In recent years, there have been a small number of primary care trials of expediting cancer diagnosis. These have focused on, for example, lowering GPs’ thresholds for diagnostic investigation, development and evaluation of educational interventions for GPs, and the use of computerised decision support tools. The findings – and design – of these trials will be presented, in order to address a number of questions:

o   What type of interventions are amenable to be trialled – and which are not?
o   How could /should we identify potential interventions for a trial?
o   What are the best designs for such trials (individual, cluster, stepped/wedge)?
o   Are participants willing to accept randomisation to control group if they are at risk of having a currently undiagnosed cancer?
o   Does the time / effort / resource needed to undertake such trials outweigh the benefit of a higher level of evidence over observational studies?