Stage-Specific Sensitivity of Fecal Immunochemical Tests for Detecting Colorectal Cancer: Systematic Review and Meta-Analysis

Fecal immunochemical tests (FITs) are used for colorectal cancer (CRC) screening in a large and increasing number of countries (1). Multiple large-scale screening cohorts have demonstrated that FITs detect the majority of CRCs. In a meta-analysis from 2019, pooled sensitivity ranged from 71% (95% confidence interval [CI]: 56%–83%) to 91% (84%–95%), and specificity ranged from 90% to 95% (2). However, little is known on the sensitivity of FIT for detecting CRC at individual stages because many of the individual studies did not report stage-specific sensitivities, and no meta-analysis of stage-specific sensitivities was conducted. The ability of FITs to detect CRC at early stages is of particular relevance for their use in CRC screening, as chances of cure of CRC are dramatically higher when they are detected in earlier rather than later stages (3). Despite numerous studies reporting on stage-specific test characteristics of FIT (4–43), only one study to date (22) focused on this outcome. Given the small case numbers from the studies conducted among asymptomatic screening participants, obtaining reasonably precise stage-specific estimates of sensitivity from such studies is difficult if not impossible. Much larger case numbers have been included in the studies conducted among symptomatic participants who were diagnosed with CRC following colonoscopy for clarification of symptoms (symptomatic/diagnostic cohorts) or who were recruited after CRC diagnosis and compared with healthy controls in a clinical setting (case-control studies). Although overall sensitivity is expected to be higher among these patient groups than among average-risk participants undergoing screening colonoscopy due to spectrum bias, stage-specific sensitivity may be comparable (44). In that case, the possibility of recruiting larger number of CRC patients in such settings might enable estimating stage-specific sensitivities of FIT irrespective of the study type at much higher levels of precision. Our aim was therefore to systematically review and compare the estimates of the stage-specific sensitivity of FIT for CRC detection from various types of studies and, if possible, summarize them to derive reasonably precise estimates of stage-specific sensitivities.