Interpreting cancer and inflammatory bowel disease risk in patients with abdominal symptoms

A team of CanTest collaborators at University College London and the University of Exeter has just published a new paper at PLoS Medicine, on the risk of cancer and of another important illness (inflammatory bowel disease) in primary care patients presenting with common abdominal symptoms (1).

The main driver behind the study was to tackle the issue of assessing cancer risk in patients presenting with abdominal symptoms, which is challenging as the positive predictive values are low. And even when a doctor suspects cancer, it is often hard to recognise the most likely underlying organ involved, which is critical for guiding the optimal choice of tests or of the hospital specialty that the patient should be referred.

The second driver was the realisation that the same abdominal symptoms may be a sign of other important illness, other than cancer. For example, inflammatory bowel disease, is a significant condition that needs specialist assessment and investigations and which, just like cancer, is often associated with diagnostic delay (2). Considering the risk of cancer and inflammatory bowel disease conjointly may enable specialist referrals for a greater number of patients at risk of either disease.

These challenges need to be juxtaposed against the ubiquitous nature of abdominal symptoms: According to a recent 6-country European study, about 1/10 patients presenting to primary care complains of one (3).

The study first (and separately) characterised cancer risk and then inflammatory bowel disease risk, in the year post-presentation for each of the 6 studied abdominal symptoms by sex. It then considered the risk of either (any) primary cancer or of inflammatory bowel disease as a composite (see Figure 3). By doing so it was observed that most age groups in both men and women exceed the 3% risk threshold used by NICE for specialist referrals.

In further stratified analyses, the team also estimated the predictive value of pairwise abdominal symptom combinations and also the relative distribution of different cancer sites for the primary cancer (among cases) by symptom. They also examined the relative distribution of cancer sites, and the relative distribution of either cancer or Inflammatory Bowel Disease among cases.

The study was based on anonymous data from about 1.9 m patients through the UK’s Health Improvement Network (THIN) primary care database who had presented during 2000-2016.

1. Herbert A, Rafiq M, Pham TM, Renzi C, Abel GA, Price S, Hamilton W, Petersen I, Lyratzopoulos G. Predictive values for different cancers and inflammatory bowel disease of 6 common abdominal symptoms among more than 1.9 million primary care patients in the UK: A cohort study. PLoS Med. 2021;18(8):e1003708.
2. Blackwell J, Saxena S, Jayasooriya N, Bottle A, Petersen I, Hotopf M, Alexakis C, Pollok RC; POP-IBD study group. Prevalence and duration of gastrointestinal symptoms before diagnosis of Inflammatory Bowel Disease and predictors of timely specialist review: a population-based study. J Crohns Colitis. 2020 Jul 15:jjaa146.
3. Holtedahl K, Hjertholm P, Borgquist L, Donker GA, Buntinx F, Weller D, Braaten T, Månsson J, Strandberg EL, Campbell C, Korevaar JC, Parajuli R. Abdominal symptoms and cancer in the abdomen: prospective cohort study in European primary care. Br J Gen Pract. 2018;68(670):e301-e310.