Clinical Question

What is the yield of a screening program based on fecal immunochemical testing (FIT) every two years for 10 years?

Bottom Line

Over a 10-year period, the rates of detection of colorectal cancer (CRC) and advanced adenomas using FIT are similar to those seen in studies of screening colonoscopy. This does not prove that FIT reduces morbidity and mortality due to CRC as effectively as colonoscopy. Modeling concludes that a FIT-based screening program will result in half as many colonoscopies as a program based on colonoscopy, a significant reduction in cost, burden, and harm of screening. (Level of Evidence = 2b)

Synopsis

The two most widely recommended strategies for CRC screening are FIT and colonoscopy. Several trials are currently underway to compare these approaches, with cancer-specific mortality as the primary outcome. Until then, we have to rely on observational studies and modeling to understand the benefit of each approach. Although colonoscopy is more sensitive than FIT, especially for the detection of advanced adenomas, what matters is the performance over a long-term screening program, not one-time accuracy. This study reports the results of five rounds of biennial FIT in a screening population 50 to 69 years of age in the Veneto region of northern Italy. The rate of detection of CRC was the highest in the first round of screening when prevalent lesions were detected (3.3 per 1,000 people), declining in subsequent rounds and stabilizing after the third round (approximately 1 per 1,000 people). Between rounds three and six, the CRC detection rate declined slightly from 0.95 to 0.84 per 1,000 people. A similar pattern was seen for advanced adenomas, declining from 15.9 per 1,000 people to approximately 10 per 1,000 people in subsequent rounds. Over the 10-year study period, the cumulative rate of positive FIT results was 25% for men and 17.6% for women. The cumulative rate for advanced adenoma was 60 per 1,000 people, and for CRC was 8.5 per 1,000 people. These rates are similar to those seen in studies of colonoscopy in Italy and the United States.

Study design: Cohort (prospective)

Funding source: Government

Setting: Population-based

Reference: Zorzi M, Hassan C, Capodaglio G, et al. Long-term performance of colorectal cancer screening programmes based on the faecal immunochemical test. Gut. 2018;67(12):2124–2130.

Editor's Note: Dr. Ebell is Deputy Editor for Evidence-Based Medicine for AFP and cofounder and Editor-in-Chief of Essential Evidence Plus.