Non-invasive home-based tests that detect blood in patient stool samples offer an accurate and appropriate triaging method for GPs, finds research led by University of Oxford researchers. The study, which is already informing a redesign of the colorectal cancer pathway at Oxford University Hospitals NHS Foundation Trust, could prompt primary care services nationally to reprioritise symptomatic patients for urgent referral to hospital-based investigation of colorectal cancer.
With a backlog of patients awaiting investigation for possible colorectal cancer symptoms as a result of the coronavirus pandemic, simple, accurate tests are needed so those at higher-risk are given priority. Faecal immunochemical tests (FIT) can be posted to the patient as a kit or collected from the GP. It simply involves collecting one stool sample at home, which is returned for laboratory testing to search for signs of blood.
Since 2017, FIT tests have been recommended by the National Institute for health and Care Excellence to guide the referral of patients with unexplained symptoms for colorectal cancer investigation. However, the test has been the subject of some controversy in the healthcare community, with concerns raised about delayed diagnosis due to false negative results. In a 2018 survey, less than half of GPs questioned perceived the test to be accurate and preferred it over colonoscopy.
This study will give GPs the confidence to request a FIT test for patients with symptoms of colorectal cancer. FIT provides a non-invasive simple home-based test that supports urgent referral for colorectal cancer investigation if positive. If negative, the risk of cancer is similar to somebody without symptoms and immediate referral can be avoided, but patients should be given safety netting advice to reconsult if their symptoms are persistent or worsening. - Dr Brian Nicholson, an Oxford City GP and NIHR Clinical Academic lecturer in Oxford University’s Nuffield Department of Primary Care Health Sciences
To assess the diagnostic accuracy of the FIT test in symptomatic people, the team of researchers from Oxford University and the Oxford University Hospitals NHS Foundation Trust analysed the results of 14,487 FIT test requests for Oxfordshire patients with symptoms that could be colorectal cancer. Patients were followed-up via their electronic patient health record for up to 36 months for evidence of colorectal disease. The study is the first to robustly demonstrate that a positive test of 10 micrograms or more of haemoglobin per gram of sample, as recommended by NICE as a threshold for urgent referral, would detect 91% of underlying cancers in the one in 10 people with symptoms who receive a positive test.
The simple at-home kit could be used to reduce pressure on urgent NHS referral pathways by identifying patients who do not require further investigation for colorectal cancer, thereby controlling colonoscopy demand and reducing costs. FIT could also be used to reprioritise patients with colorectal cancer symptoms whose tests have been delayed by the COVID-19 pandemic, helping us avoid delayed cancer diagnosis due to the backlog. A positive FIT test from a patient tested in primary care for suspected colorectal cancer or serious colorectal disease should prompt urgent referral for definitive colorectal investigation. - Dr James East, Consultant Gastroenterologist at Oxford University Hospitals NHS Foundation Trust
The research, published in Alimentary Pharmacology & Therapeutics, is supported by the National Institute for Health Research Oxford Biomedical Research Centre as part of the molecular diagnostics theme. The research team have recently received funding from the Oxford Centre for Early Cancer Detection Funding Scheme to continue this work and further improve risk stratification for referral.