Article Text

Faecal immunochemical test is superior to symptoms in predicting pathology in patients with suspected colorectal cancer symptoms referred on a 2WW pathway: a diagnostic accuracy study
  1. Nigel D'Souza1,2,3,
  2. Theo Georgiou Delisle1,3,
  3. Michelle Chen4,
  4. Sally Benton5,
  5. Muti Abulafi1
  6. The NICE FIT Steering Group
    1. 1 Colorectal Surgery, Croydon University Hospital, Croydon, UK
    2. 2 Colorectal Surgery, Basingstoke and North Hampshire Hospital, Basingstoke, UK
    3. 3 Surgery & Cancer, Imperial College London, London, UK
    4. 4 Research & Development, RM Partners, London, UK
    5. 5 Clinical Biochemistry, Royal Surrey County Hospital, Guildford, UK
    1. Correspondence to Mr Muti Abulafi, Colorectal Surgery, Croydon University Hospital, Croydon CR7 7YE, UK; muti.abulafi{at}nhs.net

    Abstract

    Objective To assess whether a faecal immunochemical test (FIT) could be used to select patients with suspected colorectal cancer (CRC) symptoms for urgent investigation.

    Design Multicentre, double-blinded diagnostic accuracy study in 50 National Health Service (NHS) hospitals across England between October 2017 and December 2019. Patients referred to secondary care with suspected CRC symptoms meeting NHS England criteria for urgent 2 weeks wait referral and triaged to investigation with colonoscopy were invited to perform a quantitative FIT. The sensitivity of FIT for CRC, and effect of relevant variables on its diagnostic accuracy was assessed.

    Results 9822 patients were included in the final analysis. The prevalence of CRC at colonoscopy was 3.3%. The FIT positivity decreased from 37.2% to 19.0% and 7.6%, respectively, at cut-offs of 2, 10 and 150 µg haemoglobin/g faeces (µg/g). The positive predictive values of FIT for CRC at these cut-offs were 8.7% (95% CI, 7.8% to 9.7%), 16.1% (95% CI 14.4% to 17.8%) and 31.1% (95% CI 27.8% to 34.6%), respectively, and the negative predictive values were 99.8% (95% CI 99.7% to 99.9%), 99.6% (95% CI 99.5% to 99.7%) and 98.9% (95% CI 98.7% to 99.1%), respectively. The sensitivity of FIT for CRC decreased at the same cut-offs from 97.0% (95% CI 94.5% to 98.5%) to 90.9% (95% CI 87.2% to 93.8%) and 70.8% (95% CI 65.6% to 75.7%), respectively, while the specificity increased from 64.9% (95% CI 63.9% to 65.8%) to 83.5% (95% CI 82.8% to 84.3%) and 94.6% (95% CI 94.1% to 95.0%), respectively. The area under the receiver operating characteristic curve was 0.93 (95% CI 0.92 to 0.95).

    Conclusion FIT sensitivity is maximised to 97.0% at the lowest cut-off (2 µg/g); a negative FIT result at this cut-off can effectively rule out CRC and a positive FIT result is better than symptoms to select patients for urgent investigations.

    Trial registration number ISRCTN49676259.

    • endoscopy
    • colonoscopy
    • colorectal cancer
    • stool markers
    • clinical decision making

    Data availability statement

    No data are available.

    https://creativecommons.org/licenses/by/4.0/

    This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https://creativecommons.org/licenses/by/4.0/.

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    Supplementary materials

    • Supplementary Data

      This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.

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    Footnotes

    • Twitter @mrnigeldsouza, @muti192

    • Correction notice This article has been corrected since it published Online First. The formatting of the last column in table 5 has been corrected.

    • Collaborators The NICE FIT Steering Group: Oliver Warren; Saidyousuf Ahmadi; Carlene Parchment; Arun Shanmuganandan; Nicholas West; Toni Mitchell; Stephen Sah; Nick Jackson; Alistair Myers; Paul Ziprin; Ian Bloom; Stan Kaye; Andy Ramwell; John T Jenkins; Kevin Monahan.

    • Contributors ND and MA were responsible for conception and design of the study. ND, TGD, MC, SB and MA were responsible for data analysis and interpretation, and critical revision of the manuscript. The trial steering group provided oversight of recruitment activity, data analysis and interpretation. All authors were responsible for data acquisition. MA is the guarantor of the study, and affirms that the manuscript is an honest, accurate and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as originally planned (and, if relevant, registered) have been explained.

    • Funding This study was funded by NHS England awarded to RM Partners, the West London Cancer Alliance hosted by The Royal Marsden NHS Foundation Trust. The study is supported by the National Institute for Health Research Clinical Research Network Portfolio. Croydon University Hospital acted as study sponsor. Alpha Labs Ltd, particularly Matthew Davis and Emma Boxall, supported the study by providing FIT collection devices without charge. All FIT kits and reagents were provided by Alpha Labs Ltd. The study was supported by Croydon University Hospital and RM Partners in the design and conduct of the trial.

    • Disclaimer The study sponsors and funders had no role in study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication.

    • Competing interests All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf.

    • Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods section for further details.

    • Provenance and peer review Not commissioned; externally peer reviewed.

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