Date of Award

Winter 3-3-2018

Document Type


Degree Name

Doctor of Philosophy (PhD)


Computational Analysis and Modeling

First Advisor

Eric Sherer


Colorectal cancer (CRC), if not detected early, can be costly and detrimental to one's health. Screening techniques for colorectal cancer can help find and remove adenomas in an effort to prevent future CRC. A colonoscopy has the potential of identifying CRC early as well as preventing the disease. Fecal Immunochemical Tests (FITs) is an initial non-invasive screening technique that identifies the presence of the disease, and needs to be followed by a more invasive test (like colonoscopy) if anything is detected. However, the optimal frequency for follow-up colonoscopy, and screening colonoscopy with FITs is unknown, and may vary based on findings from colonoscopy screening and patient age.

A partially observed Markov process (POMP) was used to simulate the effects of a follow-up colonoscopy, FITs, and a combination of colonoscopy and FITs on the development of CRC. The POMP uses adenoma and CRC growth models to calculate the probability of an individual having colorectal adenomas and CRC. Then, based on mortality, quality of life, and the costs associated with diagnosis, treatment, and surveillance of colorectal cancer, the overall costs and increase in quality adjusted life years are calculated for each follow-up colonoscopy, FIT and colonoscopy combination, and FIT scenario.

This study found that spending $100,000 for a quality adjusted life year (QALY) gained will produce one follow-up colonoscopy after screening at age 50 years. The optimal follow-up is 8.5 years later which gives 84.0 QALYs gained/10,000 persons). No follow-up colonoscopy was cost-effective at the $50,000 and $75,000/QALY gained thresholds. The intervals were relatively insensitive to the findings at screening colonoscopy.

Combining screening techniques for CRC (colonoscopy and FIT) is cost-effective at all three thresholds analyzed. All screening ages tested were cost-effective with approximately an 8 year increase in QALYs from screening age 50 to screening age 75. As a result of the protocol of combining screening tests being extremely cost-effective with added benefit (QALYs gained), coupling the tests is highly recommend.