Background: Faecal occult blood tests (FOBTs) are used for colorectal cancer (CRC) screening. We aimed to assess the sensitivity of an immunochemical FOBT for detecting advanced colorectal neoplasia in the left vs the right colon and to explore reasons for potential differences in site-specific test performance.Methods: We prospectively measured faecal occult blood levels by a quantitative immunochemical FOBT (RIDASCREEN) in 2310 average-risk subjects undergoing screening colonoscopy. We compared diagnostic performance for subjects with left- vs right-sided advanced neoplasia, as well as patient characteristics and adenoma characteristics that have been suggested to impact faecal haemoglobin levels. Results: Sensitivities for subjects with left- vs right-sided advanced neoplasia were 33% (95% confidence interval (CI), 26-41%) and 20% (CI, 11-31%) (P0.04) at a specificity of 95% (overall sensitivity: 29%) and the areas under the receiver-operating characteristics curve were 0.71 (CI, 0.69-0.72) and 0.60 (CI, 0.58-0.63), respectively. Pedunculated shape was strikingly more common in participants with left- vs right-sided advanced neoplasia (47% vs 14%). In logistic regression analyses adjusted for site, pedunculated shape was statistically significantly associated with test sensitivity (P0.04).Conclusions:The immunochemical FOBT in our study was more sensitive for detecting subjects with left- vs right-sided advanced colorectal neoplasia. Our findings may stimulate further diagnostic research in the field as well as modelling analyses to estimate the potential effect of site-specific test performance on the effectiveness of annual or biennial FOBT-based screening programmes, in particular with respect to protection from right-sided CRC.
Bibliographical noteFunding Information:
We gratefully acknowledge the excellent contributions of Isabel Lerch in data collection, coordination and monitoring of the BliTz study, the excellent cooperation with gastroenterological practices regarding recruitment of study participants and the excellent cooperation with Labor Limbach (Heidelberg) in test execution. The study was partly supported by the German Research Foundation (DFG) within the framework of a PhD programme (Graduiertenkolleg 793). Stool tests were provided by the manufacturer free of charge. The sponsors had no influence on study design, data collection, monitoring, analysis and interpretation of results or the decision to submit the paper for publication.
- colorectal neoplasia
- faecal occult blood testing