First, second FIT-based screenings 'equally likely' to detect CRC at early stage
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Key takeaways:
- Colorectal cancer detected via fecal immunochemical test was equally likely to be diagnosed stage I to II at first and second screenings.
- Most CRCs would still be stage I to II if FIT level cutoff was increased.
Fecal immunochemical test-based screening was effective in detecting early-stage colorectal cancer at first and repeat screenings, with higher FIT cutoff levels having little effect on stage distribution, data showed.
“CRC screening programs using fecal immunochemical testing for occult blood showed that screen-detected CRCs are more often diagnosed at stage I to II (66%-71%) than clinically detected CRCs (40%-57%),” Arthur I. Kooyker, MD, PhD, of the department of public health at Erasmus University Medical Center, and colleagues wrote in Clinical Gastroenterology and Hepatology. “Because these results were predominantly based on CRCs detected at first screening, it remains unclear whether the stage-distribution of CRCs detected at repeat screenings will remain as favorable.”
Using data from a population-based Dutch CRC screening program, Kooyker and colleagues evaluated 266,434 individuals who had a positive FIT (cutoff 47µg Hb/g feces) at first (n = 205,035) or second (n = 61,399) screening between January 2014 and December 2018.
Follow-up colonoscopies yielded 15,755 CRC diagnoses at first screening (mean age at diagnosis, 67.2 years; 62.1% men) and 3,304 at second screening (mean age, 67.4 years, 55.7% men).
Researchers reported CRCs were “equally likely” to be diagnosed at stage I to II at first or second screening (66.5% vs. 67.7%, respectively; RR = 1.02; 95% CI, 0.996-1.05). Although the probability of a stage I to II diagnosis was similar in men vs. women (RR= 0.99; 95% CI, 0.96-1.01), it was higher among those aged 70 to 76 years vs. 55 to 59 years (RR = 1.07; 95% CI, 1.03-1.09).
When hypothetically increasing the FIT cutoff from 47 µg to 250 µg, researchers estimated a reduction of detected CRCs by 88.3% at first screening and 79% at second screening. However, they noted most diagnoses (63%-64%) would still be stage I to II.
“The majority of CRCs detected by FIT-based screening are diagnosed at stage I or II, also at repeat screening,” Kooyker and colleagues concluded. “Screening becomes much less effective when increasing the FIT cutoff level due to a vast decrease in CRC detection. Stage-distribution is however minimally affected by FIT cutoff level, as the missed CRCs due to higher FIT cutoff levels consider nearly as much early as late-stage CRCs.”
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