Systematic review of participation, positivity and yield over time in fecal immunochemical test-based organized colorectal cancer screening programs

Fecal immunochemical testing (FIT), the most common colorectal cancer (CRC) screening modality worldwide, requires programmatic participation over decades. We performed a systematic review and meta-analysis to ascertain overall adherence patterns, per-round participation, FIT-positivity, and neoplasia detection rates in organized FIT-based screening programs, contrasting initial vs. subsequent screening rounds. We systematically searched Pubmed, Embase and Cochrane databases. Adherence patterns were defined as consistent screeners (all rounds), intermittent screeners, and never attendants. Per-round participation, FIT-positivity, and positive predictive values (PPVs) for CRC, advanced adenoma (AA), and adenoma were determined overall and for consistent screeners. Subgroup analyses were performed by screening periodicity and FIT positivity cut-off. Of 4,414 candidate studies, 24 were included. Adherence patterns were: 47.1% (SD 11.6) consistent screeners, 22.7% (SD 4.7) intermittent screeners, and 30.3% (SD 12.2) never attendants. Overall pooled results from the first through fourth rounds showed per-round participation of 51.3 (95% CI 37.4-65.3)%, 56.7 (41.3-72.2)%, 56.9 (38.7-75.3)%, and 56.5 (44.-68.6)%; FIT-positivity of 6.6 (5.9-7.3)%, 5.6 (4.6-6.6)%, 5.3 (4.0-6.6)%, and 5.3 (3.7-6.9)%; CRC PPV of 5.8 (4.1-7.4)%, 3.3 (2.3-4-3)%, 2.9 (2.2-3.7)%, and 2.5 (1.4-3.5)%; AA PPV of 32.8 (23.5-42.0)%, 28.3 (21.8-34.7)%, 22.7 (16.5-28.9)%, and 23 (10.1-35.9)%; and adenoma PPV of 48.6 (45.8-51.4)%, 46.2 (42.4-50.1)%, 48.7 (43.9-53.6)%, and 44.6 (38.2-51.0)%, respectively. Similar trends were observed for consistent screeners and for biennial FIT with 20μg Hb/g feces positivity cut-off. Organized FIT-based CRC screening programs achieve consistent participation in nearly half of persons and no participation in approximately one third. FIT-positivity and yields for CRC, AA, and adenoma are highest in the first round and may stabilize at clinically relevant steady states at the third to fourth rounds.