Fecal immunochemical test accuracy in average-risk colorectal cancer screening

AIM:To assess the fecal immunochemical test(FIT)accuracy for colorectal cancer(CRC)and advanced neoplasia(AN)detection in CRC screening.METHODS:We performed a multicentric,prospective,double blind study of diagnostic tests on asymptomatic average-risk individuals submitted to screening colonoscopy.Two stool samples were collected and the fecal hemoglobin concentration was determined in the first sample(FIT1)and the highest level of both samples(FITmax)using the OC-sensor.Areas under the curve(AUC)for CRC and AN were calculated.The best FIT1and FITmax cut-off values for CRC were determined.At this threshold,number needed to scope(NNS)to detect a CRC and an AN and the cost per lesion detected were calculated.RESULTS:About 779 individuals were included.An AN was found in 97(12.5%)individuals:a CRC in 5(0.6%)and an advanced adenoma(≥10 mm,villous histology or high grade dysplasia)in 92(11.9%)subjects.For CRC diagnosis,FIT1 AUC was 0.96(95%CI:0.95-0.98)and FITmax AUC was 0.95(95%CI:0.93-0.97).For AN,FIT1 and FITmax AUC were similar(0.72,95%CI:0.66-0.78 vs 0.73,95%CI:0.68-0.79,respectively,P=0.34).Depending on the number of determinations and the positivity threshold cut-off used sensitivity for AN detection ranged between 28%and 42%and specificity between 91%and 97%.At the best cut-off point for CRC detection(115 ng/mL),the NNS to detect a CRC were 10.2 and 15.8;and the cost per CRC was 1814€and 2985€on FIT1 and FITmax strategies respectively.At this threshold the sensitivity,NNS and cost per AN detected were 30%,1.76,and 306€,in FIT1 strategy,and 36%,2.26€and 426€,in FITmax strategy,respectively.CONCLUSION:Performing two tests does not improve diagnostic accuracy,but increases cost and NNS to detect a lesion.