Flexible sigmoidoscopy and fecal immunochemical tests are established diagnostic tests for colorectal cancer (CRC) screening and less invasive, less expensive, and easier to conduct than colonoscopy. However, little is known about their joint diagnostic performance compared to colonoscopy. We aimed to assess the expected diagnostic performance of joint use of flexible sigmoidoscopy and fecal immunochemical test.
We assessed the overall and site-specific prevalences of colorectal neoplasms and the overall and site-specific sensitivity, specificity, area under the receiver operating characteristics curve of a quantitative fecal immunochemical test (FOB Gold) among 3,466 participants in screening colonoscopy in Germany. Results were used to model the expected diagnostic performance of joint use of flexible sigmoidoscopy and fecal immunochemical testing.
CRC and advanced adenomas were found in 29 (1%) and 354 (10%) participants, respectively. The area under the curve of fecal immunochemical testing for these outcomes could be raised from 96% to 100% and from 70% to 89%, respectively, by combining it with flexible sigmoidoscopy. At 90% specificity, sensitivity of fecal immunochemical testing would increase from 97% to 100% for CRC and from 40% to 79% for advanced adenomas.
Combining flexible sigmoidoscopy and fecal immunochemical testing might strongly enhance diagnostic performance of each single test to a level close to the diagnostic performance of screening colonoscopy while avoiding many unnecessary colonoscopies.
Financial support: The BliTz study was partly funded by a grant from the German Research Council (DFG, grant No. BR1704/16-1).
Potential competing interests: None declared. The sponsors had no role in study design, data collection, monitoring, analysis, and interpretation of data.
Writing assistance: none
Availability of data and code: not available
Acknowledgements: We gratefully acknowledge the excellent cooperation of gastroenterology practices and clinics in patient recruitment and of Labor Limbach in sample collection. We also gratefully acknowledge Isabel Lerch, Susanne Köhler, Dr. Utz Benscheid, Jason Hochhaus and Maria Kuschel for their contribution in data collection, monitoring and documentation.
Financial support: This study was supported in part by a grant from the German Research Council (DFG, grant No. BR1704/16-1).
Potential competing interests: The sponsors had no role in study design, data collection, monitoring, analysis, and interpretation of data.
Author contributions: HB designed the study. TN conducted the statistical analyses and drafted the manuscript. HB, MH and KW contributed to important intellectual content and critically revised the manuscript. All authors approved the final draft submitted.
Corresponding author: Hermann Brenner, Division of Clinical Epidemiology and Aging Research, German Cancer Research Center, Im Neuenheimer Feld 581, D-69120 Heidelberg, Germany. Phone ++49-6221-421300, Fax ++49-6221-421302, E-mail email@example.com
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