Fecal immunochemical test in colorectal cancer screening: Colonoscopy findings by different cut-off levels.

Abstract

Fecal immunochemical test (FIT) is used in colorectal cancer (CRC) screening, but number of tests and cut-off level differ by program. The aim was to evaluate CRC screening with two FIT samples in average-risk 60-year-old men and women and to investigate hemoglobin (Hb) level in correlation to adenoma characteristics. We analyzed a cohort from Screening of Swedish Colons trial where participants with at least one of two FIT samples ≥10μgHb/g are offered colonoscopy. FIT levels and colonoscopy findings were assessed in multivariable analyses. Cut-off levels 10-80μgHb/g for one and two samples were assessed. FIT levels and advanced neoplasia (AN) were investigated by gender. A total of 12383 participated and 1182 positives (551 women) completed colonoscopy diagnosing 27 (2.3%) CRC and 269 (23%) advanced adenomas (AA). Median FIT level was 241.0 and 23.8 for CRC and AA compared with 13.4-15.8 in other subgroups (P=0.002) correlating with adenoma size (P=0.038). CRC was detected in 22 and 19 subjects for the first sample at cut-off 20 and 40μgHb/g, compared with 20 and 17 for the mean of two samples at cut-off 40 and 80μgHb/g (P<0.05). Men had more AN (CRC+AA), (P=0.003). In women, similar number of AN would be detected with cut-off lowered from 40 to 20 or from 80 to 40μgHb/g, requiring additional 26-34% colonoscopies. In average-risk 60-year-olds, FIT was higher in participants with AN and correlated with adenoma size. FIT screening with one sample at low cut-off detected more CRC than two samples at higher cut-off. Applying lower cut-off in women to equalize gender differences in AN would result in considerable increase in colonoscopy workload.