Effects and Costs of Colorectal Cancer Screening and Follow-up after Polypectomy

textabstractColorectal cancer is a major public health problem in many countries. In 1997, approximately 8,500 new cases of colorectal cancer were diagnosed in the Netherlands and more than 4,000 individuals died from this disease. Screening for colorectal cancer in the general population has the potential to save lives. Potential screening tests are the fecal occult blood test (FOBT), colonoscopy and sigmoidoscopy. FOBT tests detect blood in stool from bleeding asymptomatic colorectal cancer or large adenomas. Sigmoidoscopy and colonoscopy are both endoscopic tests that visualize the colorectal tract. If adenomas, precursors of cancer, are detected at the screening test, they can be removed immediately. It is recommended that patients with removed adenomas undergo regular colonoscopic surveillance. In this thesis, aspects of colorectal cancer screening and of colonoscopic surveillance (follow-up) of adenoma patients are studied by analysis of relevant data and with the use of the MISCAN-COLON model. This is a micro-simulation model that simulates a large number of fictitious individual life histories. The three main uses of the model are analysis of data of population studies in the field of screening and surveillance of adenoma patients, testing of hypotheses about the natural history of adenomas and colorectal cancer, and evaluation of screening policies. General conclusions The MISCAN-COLON model is a useful tool for the analysis of screening and surveillance studies and for the evaluation of screening strategies. A wide variation is seen among the different models regarding the assumptions on the adenoma dwell time and the percentage of colorectal cancers that originate from adenomas. Screening for colorectal cancer using fecal occult blood tests reduces colorectal cancer mortality and is cost-effective