Can the Parallel or Tandem Combination of Questionnaire-Based Risk Assessment and Fecal Immunochemical Test Improve...

Colorectal cancer (CRC) screening reduces disease burden, but the comparative performance of various screening strategies remains unclear. We evaluated the performance of four screening strategies based on questionnaire-based risk assessment (QRA) and fecal immunochemical test (FIT), followed by colonoscopy. In this population-based study, 14,327 residents aged 40-74 years from 13 regions in Shandong Province, China, were invited to undergo QRA, FIT, and colonoscopy between January 2024 and December 2025. Based on test results, we constructed four strategies: QRA-only, FIT-only, parallel (QRA or FIT positive), and tandem (QRA and FIT positive) combinations. The detection rate of CRC and advanced adenoma (AA), number needed to scope (NNS), and cost per case detected were compared. In total, 4982, 1806, 5970, and 764 individuals were identified as high-risk for each strategy. The tandem strategy detected 33 CRCs (4.32%) and 199 AAs (26.03%), compared with 35 (0.71%) and 553 (11.22%) in the QRA-only strategy, 68 (3.77%) and 340 (18.86%) in the FIT-only strategy, and 70 (1.17%) and 694 (11.62%) in the parallel strategy. Across subgroups defined by older age, male, and early-stage disease, the tandem strategy consistently yielded higher detection rates. The NNS to detect one CRC was 141, 27, 86, and 24, and the corresponding costs per CRC detected were $9874.31, $2097.88, $7084.68, and $1700.71 for each strategy. The tandem strategy combining QRA and FIT demonstrated superior performance in CRC screening. In resource-constrained settings, tandem strategies that jointly integrate risk assessment and FIT may improve the allocation and utilization of screening resources.