Theme 3.2 - Modelling Investigative Pathways

  • Lead Investigator: Prof Tony Ades
  • Researchers: to be appointed Jan 2013

The aim is to identify the most cost effective investigative pathways for patients presenting to GPs with symptoms that could trigger further investigations for cancer, including the most cost effective thresholds for referral.

This project is estimated to take 18 months and will start at the beginning of Year 4 after all previous projects have been completed.


This project will consider changes in the risk threshold for referral to secondary care and an increase in GP access to diagnostic services like colonoscopy, ultrasound or CT scanning. This will be achieved by using probabilistic Cost Effectiveness Analysis (CEA) modelling, taking the perspective of an "expected value" national NHS decision maker. This exercise will be carried out for colorectal and pancreatic cancers.


A Risk Score is assigned to an individual patient which changes with time. The objective of the CEA is to identify the most cost effective threshold for referral, taking into account the differing sensitivity and specificity of the risk score for cancer and the additional costs and benefits of earlier referral, diagnosis and treatment. A decision tree has been created which models the decisions to investigate and refer and the time when diagnosis is inevitable.

The essential purposes of the CEA are to identify the optimal point in disease progression at which GP referral to secondary care is most cost effective and to evaluate the potential role of GPs having direct access to investigations compared to access only through secondary care. The overall potential benefits against current diagnostic pathways can also be identified.

There is an inherent assumption behind this approach that there is a patient advantage in both earlier diagnosis and earlier treatment. The trade off is between the increased frequency of costly investigations for those who do not have cancer and the increased costs of care for those who do versus the quality and length of life gains due to earlier treatment. These health gains are measured in Quality Adjusted Life Years (QALYs) and given a monetary value. This methodology is the same as used to develop guidance for introduction of new interventions by NICE.


The results will inform commissioners of care of the theoretical best choice for the provision of cancer diagnostics. They will also be fed to NICE for review of the referral guidelines and to the PCT panels in Project 3.3 for implementation development. There will also be the conventional research outputs.

For more news, click here

10th February 2016

New Discovery Research publication

The SYMPTOM Study team's research into symptom appraisal for colorectal cancer has been published in BMJ Open. This is a unique piece of research which compares the appraisal and help seeking experiences of patients with colorectal cancer symptoms who go on to have cancer and those who turn out to have non-cancer conditions. The research did not identify any clear differences between the two groups but did identify important barriers to presentation around the ‘private nature’ of colorectal symptoms which will prove useful to policy makers and the design of awareness campaigns. To read more about the research paper see the results section here.

9th June 2015

Discovery conference slides available & new research publications

The Discovery Programme held its research conference at the Royal College of General Practitioners on June 2nd 2015. The team presented their research findings and outlined the impact of the programme to a wide range of patient groups, clinicians, policy makers, researchers and journalists. The PowerPoint slides used during the presentation have been uploaded to this website and can be viewed here.

There are also 2 new research papers to report. Chantal Balasooriya-Smeekens has published the literature review of her PhD in Psycho-Oncology, "The role of emotions in time to presentation for symptoms suggestive of cancer: a systematic review of quantitative studies". Abstract and publication details are here and further papers from Chantal's PhD will be published soon.

Nafees Din has published a new paper under the Discovery related research umbrella. The paper uses Discovery data drawn from the CAPER (theme 2) studies and considers "Age and Gender Variations in Cancer Diagnostic Intervals in 15 Cancers". Full publication details and abstract can be found here.