Anaemia and FIT negative and the urgent lower GI cancer referral pathway
Chapman et al undertook a study where a postal FIT (faecal immunochemical test) was incorporated into the colorectal cancer 2-week wait (2WW) pathway for all patients without rectal bleeding in 2016
- patients were investigated in the 2WW pathway as normal, and outcomes of investigations were recorded prospectively. Anaemia was defined as a haemoglobin level below 120 g/l in women and 130 g/l in men
- FIT kits were sent to 1106 patients, with an 80.9 per cent return rate; 810 patients completed investigations and 40 colorectal cancers were diagnosed (4.9 per cent)
- FIT results were significantly higher in patients with anaemia (median (i.q.r.) 4.8 (0.8-34.1) versus 1.2 (0-6.4) µ g Hb/g faeces in those without anaemia; P <0.001)
- 60.4 per cent of patients (538 of 891) had a result lower than 4 µ g haemoglobin (Hb) per g faeces (limit of detectability), and 69.7 per cent (621 of 891) had less than 10 µg Hb/g faeces
- 60 per cent of patients with colorectal cancer had a FIT reading of 150 µg Hb/g faeces or more
- for five colorectal cancers diagnosed in patients with a FIT value below 10 µg Hb/g faeces, there was either a palpable rectal mass or the patient was anaemic
- therefore of 1/8 (12.5%) CRC diagnosed with a FIT of below 10 µg then these were either had palpable mass or were anaemic
Right sided lesions versus left-sided lesions
- right-sided cancers were associated with a significantly lower FIT result than left-sided lesions (median 41.6 (i.q.r. 11.2-406.8) versus 286.8 (142-5076.8) µg Hb/g faeces respectively; P= 0.030)
A further evaluation in 2021 showed (2):
- 18/223 CRC (8%) of cancers had a FIT <10 µg
In this pathway a FIT at a level of 4 µg haemoglobin (Hb) per g faeces in anaemia was used to identify patients appropriate (or not) for urgent lower GI referral and the authors noted:
- a threshold as low as 4 µg Hb/g faeces in patients with anaemia, low ferritin and thrombocytosis was driven by concern around the use of FIT in "high risk" patients, but is vindicated by the detection of nine such patients with colorectal cancer in the cohort with fHb below 10 µg Hb/g faeces
- i.e. 50% of the patients with CRC and a FIT < 10 µg
Reference:
- Chapman C, Bunce J, Oliver S, Ng O, Tangri A, Rogers R, Logan RF, Humes DJ, Banerjea A. Service evaluation of faecal immunochemical testing and anaemia for risk stratification in the 2-week-wait pathway for colorectal cancer. BJS Open. 2019 Jan 28;3(3):395-402.
- Bailey JA, Weller J, Chapman CJ, Ford A, Hardy K, Oliver S, Morling JR, Simpson JA, Humes DJ, Banerjea A. Faecal immunochemical testing and blood tests for prioritization of urgent colorectal cancer referrals in symptomatic patients: a 2-year evaluation. BJS Open. 2021 Mar 5;5(2):zraa056. doi: 10.1093/bjsopen/zraa056