Interval cancers in a national colorectal screening programme based on faecal immunochemical testing: implications for faecal haemoglobin concentration threshold and sex inequality

TY - JOUR

T1 - Interval cancers in a national colorectal screening programme based on faecal immunochemical testing

T2 - implications for faecal haemoglobin concentration threshold and sex inequality

AU - Clark, Gavin R. C.

AU - Godfrey, Thomas

AU - Purdie, Calum

AU - Strachan, Judith

AU - Carey, Francis A.

AU - Fraser, Callum G.

AU - Steele, Robert J. C.

N1 - Copyright: © The Author(s) 2023.

PY - 2024/3

Y1 - 2024/3

N2 - Objective: To compare interval cancer proportions (ICP) in the faecal immunochemical test (FIT)-based Scottish Bowel Screening Programme (SBoSP) with the former guaiac faecal occult blood test (gFOBT)-based SBoSP and investigate associations between interval cancer (IC) and faecal haemoglobin concentration (f-Hb) threshold, sex, age, deprivation, site, and stage. Methods: The ICP data from first year of the FIT-based SBoSP and the penultimate year of the gFOBT-based SBoSP were compared in a prospective cohort design. Results: With FIT, 801 colorectal cancers (CRCs) were screen detected (SDC), 802 were in non-participants, 548 were ICs, 39 were colonoscopy missed and 72 were diagnosed after incomplete screening; with gFOBT: 540, 904, 556, 45, and 13, respectively. FIT had a significantly higher proportion of SDC compared to IC than gFOBT. For FIT and gFOBT, ICP was significantly higher in women than men. As f-Hb threshold increased, ICP increased and, for any f-Hb threshold for men, a lower threshold was required for comparable ICP in women. In Scotland, the current threshold of ≥80 µg Hb/g faeces would have to be lowered to ≥40 µg Hb/g faeces for women to achieve sex equality for ICP. In the FIT-based SBoSP, there were four times as many stage I SDC than IC. This was reversed in advanced stages, with twice as many stage IV CRC diagnosed as IC versus SDC. Conclusions: Reducing the numbers of IC requires lowering the f-Hb threshold. Using different f-Hb thresholds for women and men could eliminate the sex disparity, but with additional colonoscopy.

AB - Objective: To compare interval cancer proportions (ICP) in the faecal immunochemical test (FIT)-based Scottish Bowel Screening Programme (SBoSP) with the former guaiac faecal occult blood test (gFOBT)-based SBoSP and investigate associations between interval cancer (IC) and faecal haemoglobin concentration (f-Hb) threshold, sex, age, deprivation, site, and stage. Methods: The ICP data from first year of the FIT-based SBoSP and the penultimate year of the gFOBT-based SBoSP were compared in a prospective cohort design. Results: With FIT, 801 colorectal cancers (CRCs) were screen detected (SDC), 802 were in non-participants, 548 were ICs, 39 were colonoscopy missed and 72 were diagnosed after incomplete screening; with gFOBT: 540, 904, 556, 45, and 13, respectively. FIT had a significantly higher proportion of SDC compared to IC than gFOBT. For FIT and gFOBT, ICP was significantly higher in women than men. As f-Hb threshold increased, ICP increased and, for any f-Hb threshold for men, a lower threshold was required for comparable ICP in women. In Scotland, the current threshold of ≥80 µg Hb/g faeces would have to be lowered to ≥40 µg Hb/g faeces for women to achieve sex equality for ICP. In the FIT-based SBoSP, there were four times as many stage I SDC than IC. This was reversed in advanced stages, with twice as many stage IV CRC diagnosed as IC versus SDC. Conclusions: Reducing the numbers of IC requires lowering the f-Hb threshold. Using different f-Hb thresholds for women and men could eliminate the sex disparity, but with additional colonoscopy.

KW - colonoscopy

KW - colorectal cancer screening

KW - faecal immunochemical test

KW - faecal haemoglobin

KW - faecal occult blood test

KW - interval cancers

U2 - 10.1177/09691413231188252

DO - 10.1177/09691413231188252

M3 - Article

C2 - 37469171

SN - 0969-1413

VL - 31

SP - 21

EP - 27

JO - Journal of Medical Screening

JF - Journal of Medical Screening

IS - 1

ER -