One-sample testing best for screening programs
Using one stool sample keeps detection similar while reducing follow-up colonoscopies and improving participation.
*Systematic review and meta-analysis of comparative studies; Level 2a (OCEBM).

Citation

Ye L, Hou QL, Peng H, Yang Q. One- versus two-sample fecal immunochemical testing for colorectal cancer screening: a systematic review and meta-analysis of participation, diagnostic performance, and cost-effectiveness. BMC Gastroenterology. 2026 (Article in Press). https://doi.org/10.1186/s12876-026-04954-8

Background

Colorectal cancer screening often uses a fecal immunochemical test, but programs vary between collecting one versus two stool samples, which may affect accuracy and workload for colonoscopy.

Patients

Asymptomatic, average-risk adults in screening settings; studies focused on higher-risk populations were excluded.

Intervention

One-sample fecal immunochemical testing per screening round.

Control

Two-sample fecal immunochemical testing (typically “any positive sample” counted as positive).

Outcome

Participation, positive test rate, cancer detection, detection of advanced precancer findings, test accuracy, positive predictive value, colonoscopy referral, and cost-effectiveness.

Follow-up Period

Varied; commonly about 6 months for completion, with some multi-round screening data.

Results

Five clinical studies (45,888 invitees) and three economic evaluations were included.
Outcome Favored strategy Effect
Participation One-sample Risk ratio 1.05 (95% CI 1.03–1.06)
Positive test rate Two-sample Risk ratio 0.65 (0.60–0.71)
Colorectal cancer detection Two-sample Risk ratio 0.62 (0.41–0.94)
Advanced precancer detection Neither NS
Positive predictive value (advanced precancer) One-sample Risk ratio 1.21 (1.06–1.38)
Colonoscopy referrals One-sample Risk ratio 0.64 (0.58–0.70)
Economic evaluations across several health systems consistently favored one-sample testing due to better efficiency and lower costs.

Limitations

Only a small number of direct-comparison studies were available, with variation in test brands and cutoffs. The cancer-detection advantage for two-sample testing was not significant when limited to first-round screening in sensitivity analyses. Long-term outcomes (mortality, interval cancers) were limited.

Funding

No funding reported.

Clinical Application

Prefer one-sample stool testing for average-risk screening programs, especially where colonoscopy capacity is limited; reserve two-sample testing for settings prioritizing maximum sensitivity.