Abstract
Minimal evidence exists regarding faecal immunochemical tests (FITs) for colorectal cancer (CRC) site, stage and grade in symptomatic patients. The primary aim is to determine any association between faecal haemoglobin concentration (f-Hb) (analysed with OC-Sensor™ Pledia) and these prognostic factors. The secondary aim is to determine the association between f-Hb and anaemia, microcytosis and iron deficiency (Hb, mean corpuscular volume [MCV] and ferritin).
Symptomatic 2-week wait CRC patients with FIT were included (July 2019-October 2022). Median f-Hb and interquartile range according to sex, stage, grade and site (right-sided, caecum to transverse colon, R-CRC; left-sided, splenic flexure to rectum, L-CRC) were compared using the Mann-Whitney U test. Hb, MCV and ferritin were categorized into two groups and the median f-Hb was compared using the Mann-Whitney U test.
In all, 114 patients (57 women, 57 men) were studied; 46 had R-CRC (f-Hb = 113 μg Hb/g) and 68 had L-CRC (f-Hb = 342 μg Hb/g) (P = 0.07). Sixty-nine were moderately differentiated CRC (f-Hb = 183 μg Hb/g) and 29 were poorly differentiated (f-Hb = 866 μg Hb/g) (P = 0.04). By T-stage, 35 were early (T1/2) (f-Hb = 170 μg Hb/g) and 79 were advanced (T3/4) (f-Hb = 200 μg Hb/g) (P = 0.06). The relationship between f-Hb and Hb, MCV and ferritin was not significant. Poorly differentiated (P = 0.04) and later stage (P = 0.02) R-CRC had significantly lower f-Hb compared to L-CRC.
Right-sided CRC is associated with lower f-Hb than left. Poorly differentiated and later staged L-CRC had higher median f-Hb. These data add to existing evidence suggesting that FIT may be less sensitive for right-sided CRC. Strategies to mitigate the potential for missed or FIT-negative right-sided CRC are required.