A novel blood based triage test for colorectal cancer in primary care: a pilot study

Abstract

BackgroundThe majority of colorectal cancers (CRCs) are detected after symptomatic presentation to primary care. Given the shared symptoms of CRC and benign disorders it is challenging to manage this risk of missed diagnosis. Colonoscopy resources cannot keep pace with increasing demand. There is a pressing need for access to simple triage tools in primary care to help prioritise patients for referral.AimTo evaluate the performance of a novel spectroscopy-based CRC blood test in primary care.Design & settingMixed methods pilot study of test performance and GP focus group discussions.MethodUrgent suspected cancer patients were recruited for the Raman spectroscopy (RS) test coupled to machine learning classification (‘Raman-CRC’) to identify CRC within the referred population. Qualitative focus group work evaluated the acceptability of the test in primary care by thematic analysis of focus group theorising.Results532 patients age over 50 referred on the USC pathway were recruited from 27 GP practices. Twenty nine patients (5%) were diagnosed with CRC. Raman-CRC identified CRC with sensitivity 95.7%, specificity 69.3% with Area Under Curve (AUC) of 0.80 as compared to colonoscopy as reference test (248 patients). Stage I/II cancers were detected with 78.6% sensitivity. Focus group themes underlined the convenience of a blood test for the patient and the test’s value as a risk assessment tool in primary care.ConclusionsOur findings support this novel, non-invasive blood-based method to prioritise those patients most likely to have CRC. Raman-CRC may accelerate access to diagnosis with potential to improve cancer outcomes.

Patient and healthcare professionals' perceptions of a combined blood and faecal immunochemical test for excluding colorectal cancer diagnosis in primary care

“…These include the faecal immunochemical test (FIT) which detects haemoglobin in a faecal sample and the blood‐based Raman‐CRC spectroscopy test 6 . Individually, both tests have high negative predictive values (over 98%) for CRC 7,8 . FIT was introduced in 2017 for low‐risk symptom triage in primary care (National Institute for Health and Care Excellence [NICE] Diagnostics guidance [DG30]) 9 with evidence growing for its use in high‐risk symptoms meeting NICE NG12 criteria.…”

“… 6 Individually, both tests have high negative predictive values (over 98%) for CRC. 7 , 8 FIT was introduced in 2017 for low‐risk symptom triage in primary care (National Institute for Health and Care Excellence [NICE] Diagnostics guidance [DG30]) 9 with evidence growing for its use in high‐risk symptoms meeting NICE NG12 criteria. However, FIT alone may not be the ideal triage tool for primary care use given its low patient compliance rate 10 , 11 (just 62% of patients in the NICE FIT study), and the fact that it is not currently approved by NICE in cases where rectal bleeding is present, 12 which is the commonest presenting symptom of lower GI cancer.…”