Optimizing thresholds of fecal immunochemical test for colorectal cancer screening in average-risk residents

Le résumé fourni par la source

Fecal immunochemical tests (FIT) are widely used to screen colorectal cancer (CRC), but data on optimal FIT thresholds for average-risk populations in China remain limited. In resource-constrained screening settings, threshold selection directly influences screening efficiency, colonoscopy burden, and program feasibility. We conducted a study across 13 regions in Shandong Province, China. Asymptomatic individuals aged 40 to 74 with average risk were recruited, providing stool samples and undergoing colonoscopy. Outcomes included CRC, advanced adenoma (AA), and advanced colorectal neoplasia (ACRN). Sensitivity, specificity, positive and negative predictive value were used to evaluate FIT screening performance. Screening burden was measured by the number needed to scope (NNSc). Regions were further divided according to baseline CRC incidence into relatively high- and low-incidence regions for subgroup analysis. The final analysis included 5,918 participants, with 378 (6.4%) having advanced adenomas and 28 (0.5%) colorectal cancers. At the 25 µg/g threshold, sensitivity for AA was 40.2% (95% CI: 35.2%–45.2%), for CRC was 96.4% (95% CI: 89.3%–100.0%), and for ACRN was 44.1% (95% CI: 39.4%–49.0%), while specificity was 95.6% (95% CI: 95.1%–96.2%), 93.8% (95% CI: 93.2%–94.4%), and 96.1% (95% CI: 95.6%–96.6%), respectively. The NNSc for direct colonoscopy was 211.4 per cancer and 14.6 per ACRN, compared to 14.6 per cancer and 2.2 per ACRN using a 25 µg/g FIT threshold, significantly reducing the screening burden. In subgroup analyses, a threshold of 25 µg/g appeared to provide a more favorable balance between detection and colonoscopy burden in relatively high-incidence regions, whereas in relatively low-incidence regions, a threshold of 50 µg/g mainly improved specificity and screening efficiency. FIT threshold selection plays a critical role in balancing screening effectiveness and resource utilization. A threshold of 25 µg/g appeared to provide a favorable overall balance in this average-risk population. Further analyses suggested that threshold optimization may vary across regions with different CRC incidence, although these findings require further validation before region-specific strategies can be recommended.

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