Camilla Nystrand Länsman

Colorectal cancer (CRC) is the third most common cancer worldwide and the most resource consuming and costly cancer. Primary and secondary prevention of CRC with screening can reduce deaths from the disease by removal of polyps and detection of cancer at an early curable stage. In a quasi-randomized study design, the Swedish region of Stockholm-Gotland started population-based screening in 2008. 400,000 individuals were invited or not to biennial fecal occult blood testing and were referred to colonoscopy when tested positive. After 14 years of follow-up, the CRC mortality was reduced 14% with invitation to screening. In 2026, 1,65 million people will be included in the program.The overall aim of the project is to build a CRC risk-prediction model to be used in screening practice to individualize continued screening within the program or adenoma surveillance. Together with the outcomes of screening, we will provide potential predictors to the model by analyzing associations of the colon microbiota and the exposure to modifiable and unmodifiable risk factors and CRC development. We will also evaluate the cost-effectiveness of screening regarding healthcare consumption, but also the indirect costs in a societal perspective, and biobank mucosa biopsies and blood samples for future research. Our results will provide evidence to reduce unnecessary screening follow-up while cost-effectively preserve the benefit of CRC risk- and mortality reduction with population-based screening.