Fecal immunochemical testing (FIT) is increasingly used for colorectal cancer (CRC) screening.
Dr de Wijkerslooth and colleagues from Amsterdam, The Netherlands aimed to estimate its diagnostic accuracy in invitational population screening measured against colonoscopy.
Participants aged 50 to 75 years were asked in an invitational primary colonoscopy screening program to complete one sample FIT before colonoscopy.
The researchers estimated FIT sensitivity, specificity, and predictive values in detecting CRC and advanced neoplasia (carcinomas and advanced adenomas) for cutoff levels of 50 (FIT50), 75 (FIT75), and 100 (FIT100) ng hemoglobin (Hb)/ml, corresponding with, respectively, 10, 15 and 20 microgram Hb/g feces.
A total of 1,256 participants underwent a FIT and screening colonoscopy.
|90% screening participants with CRC will be detected using one single FIT at low cutoff|
|American Journal of Gastroenterology|
Advanced neoplasia was detected by colonoscopy in 9%, 0.6% of them had CRC.
At FIT50, 10% had a positive test result; 37% had advanced neoplasia and 6% had CRC.
A total of 74 of 1,135 FIT50 negatives had advanced neoplasia including 1 CRC.
FIT50 had a sensitivity of 38% for advanced neoplasia and 88% for CRC at a specificity of 93% and 91%, respectively.
the team found that the positive and negative predictive values for FIT50 were 6% and almost 100% for CRC, and 37% and 93% for advanced neoplasia.
The researchers found that sensitivity and specificity of FIT75 for advanced neoplasia were 33% and 96%.
At FIT100, 71 screenees had a positive test result.
The sensitivity and specificity of FIT100 were for advanced neoplasia 31% and 97%, and for CRC 75% and 95%.
The team noted that the area under curve for detecting advanced neoplasia was 0.70.
FIT had a similar sensitivity for proximal and distal advanced neoplasia at cutoffs of 50, 75 and 100 ng Hb/ml.
Dr de Wijkerslooth's team conclude, "90% screening participants with CRC and 40% with advanced neoplasia will be detected using one single FIT at low cutoff."
"Sensitivity in detecting proximal and distal advanced neoplasia is comparable."