Authors:

Abstract

Aim: Faecal immunochemical testing (FIT) is simple, noninvasive and accessible test widely used in screening programmes for colorectal cancer. Though the use of FIT in detecting positive pathology has been a topic of contention, there is a strong body of evidence demonstrating FITs high negative predictive value (96100%), namely its strength in ruling out sinister disease. Recently recommendations in NICE guidelines on suspected cancer in symptomatic patients suggests its use to triage the need for referral to secondary care in patients of low risk; namely those with iron deficiency anaemia under 60 and those with anaemia (all types) over 60. The data from these recommendations are based on are from 10 cohort studies, 5 of which were deemed to have high risk of bias by the guideline authors, only 4 examine colorectal cancer alongside faecal occult blood testing, none of which examine cohorts with more than 80 colorectal cancers detected and none reporting results specific to this low risk symptomatic group that is being described. This leaves a grey area whereby management is left to the digression of primary care practitioners.

Patients: With more than 40,000 new cases of colorectal cancer being detected every year and the growing burden on secondary care, there is an urgent need to define management for this large pool of patients with anaemia and suspected colorectal cancer. More rigorous data is needed to direct referral guidelines, delineate influential factors including age, sex and medication, and stratify risk factors and pretest probability.

Intervention/Comparator: Can FIT triage and rule out sinister pathology in patients presenting with suspicious symptoms of bowel cancer who belong to a low risk demographic

Study design: We propose a multicentre diagnostic cohort study recruiting patients with anaemia and suspected colorectal cancer, who have been referred to secondary care. All patients will have a faecal occult blood test done a full blood count, urea and electrolytes and CRP and a complete drug history recorded prior to further investigation (colonoscopy/CT colonography). Data will be collected on positive pathological findings including colorectal cancer, advanced adenomas, and other causes of occult bleeding including inflammatory bowel disease and polyps. Plus, data for cancers that went onto resection will be followed up including staging and metastases. We aim to recruit 25003000 patients with the primary goal to detect 150 300 cancers and gather demographic information sufficient to analyse gender disparity, impact of medications and if detection thresholds should be altered and potentially produce a system to score and stratify this group of patients. In cost effectiveness analysis, FIT is better than both guaiacbased faecal occult blood testing and no triage and in analysis models the use of FIT could save 77% incorrect referrals to colonoscopy (true negatives), and missed only 0.2% of cancers (false negatives). This has the potential to have a significant impact on both the economic and logistical management of colorectal cancer services nationwide.