Estimation of overdiagnosis in colorectal cancer screening with sigmoidoscopy and faecal occult blood testing: comparison of simulation models

ObjectiveTo estimate overdiagnosis of colorectal cancer (CRC) for screening with sigmoidoscopy and faecal occult blood testing (FOBT).DesignSimulation study using data from randomised trials.SettingPrimary screening, UK, NorwayParticipants152 850 individuals from the Nottingham trial and 98 678 individuals from the Norwegian Colorectal Cancer Prevention (NORCCAP) trial.InterventionCRC screening.Outcome measureWe estimated overdiagnosis using long-term data from two randomised trials: the Nottingham trial comparing FOBT screening every other year to no-screening, and the NORCCAP trial comparing once-only sigmoidoscopy screening to no-screening. To estimate the natural growth of adenomas to CRC, we used the following microsimulation models: (i) the Microsimulation Screening Analysis; (ii) the CRC Simulated Population model for Incidence and Natural history; (iii) the Simulation Model of Colorectal Cancer; (iv) a model derived by the German Cancer Research Center. We defined overdiagnosed cancers as the difference between the observed number of CRCs in the no-screening arm and the expected number of cancers in screening arm (sum of observed and prevented by adenoma removal). The amount of overdiagnosis is defined as the number of overdiagnosed cancers over the number of cancers observed in the no-screening arm.ResultsOverdiagnosis estimates were highly dependent on model assumptions. For FOBT screening with 2354 cancers observed in control arm, four out of five models predicted overdiagnosis, range 2.0% (2400 cancers expected in screening) to 7.6% (2533 cancers expected in screening). For sigmoidoscopy screening with 452 cancers observed in control arm, all models predicted overdiagnosis, range 25.2% (566 cancers expected in screening) to 128.1% (1031 cancers expected in screening).ConclusionsThe amount of overdiagnosis estimated based on the microsimulation models varied substantially. Microsimulation models may not give reliable estimates of the preventive effect of adenoma removal, and should be used with caution to inform guidelines.

Exploring the Barriers Toward Colorectal Cancer Screening: A Literature Review

Background: Colorectal cancer is the third most common cancer and the second leading cause of death worldwide. Bowel cancer screening helps prevent colon cancer by early detection of polyps, leading to efficient treatment and reduced mortality. Within Qatar, primary health facilities promote bowel screening by using the faecal occult blood test. However, the popularity and use of this test is still low. Aim: The aim of this literature review is to explore barriers related to colorectal cancer bowel screening using the faecal occult blood test in primary health care settings to facilitate colorectal cancer screening in Qatar. Method: Cronin’s five step framework for literature reviews was utilized for this paper. This review included nine articles that were peer-reviewed and published between 2009 and 2019. The nine articles were appraised by using the Mixed Methods Appraisal Tool. This tool has separate criteria to assess the quality of the qualitative, quantitative, and mixed-method studies. Result: Three main barriers to bowel cancer screening included knowledge deficit, personal beliefs and organizational barriers. Conclusion: The main barriers are related to the patients’ lack of knowledge and personal beliefs. Overcoming these barriers is essential to raising awareness about this issue among all nurses, physicians, and patients. It is necessary to involve stakeholders in order to mitigate barriers. Developing educational activities for healthcare professionals will provide information that they can share with patients to encourage screening and decrease the fear of the test. Developing a pamphlet to increase patient awareness will also encourage screening and work toward decreasing fear. Key words: faecal occult blood test, faecal immunochemical test, barriers

Evaluation of two faecal occult blood diagnostic tests for detection of non-perforating abomasal lesions in cattle

The authors have requested that this preprint be withdrawn due to author disagreement.