Authors’ reply to Steele and colleagues

In response to Steele and colleagues,1 2 half of patients with colorectal cancer did not meet the criteria for urgent referral under the previous guidance. These patients, with “low risk, but not no risk symptoms” did badly, with longer times to diagnosis,3 more emergency admissions,4 and higher mortality.3 The 2015 National Institute for Health and Care Excellence (NICE) guidance sought to improve this.1

The literature review identified six research papers on faecal occult blood testing (FOBT) in the symptomatic primary care population. Overall, these supported the use of FOBT. A rigorous economic analysis of several testing options for the low risk group (including colonoscopy and no testing) found FOBT to be the most cost effective. Colonoscopy was inferior from a cost effectiveness viewpoint, and it would be impractical to extend colonoscopy to this large population. Surgeons were already worried about extra referrals; if we had recommended colonoscopy for the large low risk group, the NHS colonoscopy service may have been overwhelmed.

Steele and colleagues are worried about false negatives, which we specifically covered in a recommendation in the guidance. We need to think about the true positives, who would have no testing at all if the exhortation to ignore the guidance were followed, with diagnostic delays as a result. This could have medico-legal and clinical repercussions.

FOBT has five supportive studies in symptomatic primary care patients; faecal immunochemical tests (FITs) have none. FITs may prove superior to FOBT when more studies are performed. We deliberately future proofed the recommendation by not specifying which test should be used. If FITs later prove superior, laboratories can switch to them. Until then, FOBT provides an evidence based, cost effective test that can be used in a group of patients previously ill served by NHS cancer diagnostics. This will save lives—NICE’s intention throughout.