Faecal immunochemical testing in bowel cancer screening: Estimating outcomes for different diagnostic policies

Abstract

Objectives The National Health Service Bowel Cancer Screening Programme (NHS BCSP) in England has replaced guaiac faecal occult blood testing by faecal immunochemical testing (FIT). There is interest in fully exploiting FIT measures to improve bowel cancer (CRC) screening strategies. In this paper, we estimate the relationship of the quantitative haemoglobin concentration provided by FIT in faecal samples with underlying pathology. From this we estimate thresholds required for given levels of sensitivity to CRC and high-risk adenomas (HRA). Methods Data were collected from a pilot study of FIT in England in 2014, in which 27,238 participants completed a FIT. Those with a faecal haemoglobin concentration (f-Hb) of at least 20 µg/g were referred for further investigation, usually colonoscopy. Truncated regression models were used to explore the relationship between bowel pathology and FIT results. Regression results were applied to estimate sensitivity to different abnormalities for a number of thresholds. Results Participants with CRC and HRA had significantly higher f-Hb, and this remained unchanged after adjusting for age and sex. While a threshold of 20 μg/g was estimated to capture 82.2% of CRC and 64.0% of HRA, this would refer 7.8% of participants for colonoscopy. The current programme threshold used in England of 120 μg/g was estimated to identify 47.8% of CRC and 25.0% of HRA. Conclusions Under the current diagnostic policy of dichotomising FIT results, a very low threshold would be required to achieve high sensitivity to CRC and HRA, which would place further strain on colonoscopy resources. The NHS BCSP in England might benefit from a diagnostic policy that makes greater use of the quantitative nature of FIT.

Effectiveness Comparison Between Fecal Immunochemical Test And Colonoscopy As A Tool For Early Detection Of Colorectal Cancer

“…9 The balance between invasive and non-invasive examinations was considered to have an important role in increasing patient compliance for early detection for further diagnosis. 10,11 Although both can be used as an early detection tool and was quite sensitive in detecting colorectal cancer lesions, but fecal immunochemical test has a limited function in detecting pre-cancerous lesions compared to colonoscopy. However, if FIT is as effective as colonoscopy the use of this test as an early detection tool can reduce the cost burden significantly.…”

Impact of changes to the interscreening interval and faecal immunochemical test threshold in the national bowel cancer screening programme in England: results from the FIT pilot study

“…The FIT pilot study has been described in detail previously [4,16]. In this study, 27,238 participants (14,404 women and 12,834 men) aged 59-75 years in the Southern and Midlands and Northwest regions of England completed a FIT kit (OC-Sensor, Eiken, Japan).…”

“…Those with an f-Hb of 20 μg/ g or more were invited for further diagnostic assessments, usually by colonoscopy. Numbers of participants assessed, numbers of cancers and other abnormalities found by different f-Hb thresholds from 20 upwards have been published [4,16]. We used the number of positive tests and CRC observed to compare rates of positivity and cancer between screen episodes by logistic regression.…”

“…In this paper, we estimate sensitivity and MST for a range of f-Hb thresholds, and the consequent harvest and prevention of CRC, adenomas, advanced adenomas (AA) and interval cancers (IC) for different combinations of interval and threshold over 15 years of screening. Estimates are derived from the FIT pilot study performed in England in 2014, in which 27,238 persons were screened with FIT [4,16].…”

“…• Adenomas detected: The sum of high-, intermediate-and low-risk adenomas at each screen episode. The detailed definition was reported previously [16].…”