Due to copyright issues, an electronic copy of the thesis must be ordered from the faculty. For the faculty to have time to process the order, the order must be received by the faculty at the latest 2 days before the public defence. Orders received later than 2 days before the defence will not be processed. After the public defence, please address any inquiries regarding the thesis to the candidate.
Trial Lecture – time and place
See Trial Lecture.
Adjudication committee
- First opponent: Professor Peter Jüni, University of Oxford
- Second opponent: General Practioner Minna Johannsson, Närhälsan Herrestad vårdcentral, Cochrane Sweden
- Third member and chair of the evaluation committee: Adjunct Professor Johannes Espolin Roksund Hov, University of Oslo
Chair of the Defence
Professor Lars Aabakken, University of Oslo
Principal Supervisor
Professor Mette Kalager, Faculty of Medicine, University of Oslo
Summary
Colorectal cancer is one of the most common causes of cancer-related morbidity and mortality worldwide. To reduce this burden, most western countries have introduced population screening with endoscopy or repeated stool tests.
Many international guidelines provide strong recommendations for colorectal cancer screening. However, the knowledge base for the absolute benefits and harms of the most used screening methods is limited. The aim of the thesis was to develop a new clinical practice guideline for colorectal cancer screening, based on the current best evidence and in line with international standards for trustworthy guidelines.
The guideline was based on a systematic review of randomized controlled trials on the effect of screening, as well as modelled estimates for absolute benefits and harms in a 15-year timeframe. A multidisciplinary panel developed the recommendations using GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology, and incorporated explicit judgments of values and preferences.
Screening can reduce the incidence and mortality of colorectal cancer, but may also cause serious adverse events such as bleeding or bowel perforations. The absolute benefits vary with the risk of developing cancer, while the harms are less dependent on the baseline risk.
The guideline emphasizes the need for shared decision-making when making screening decisions, but suggests no screening if the 15-year risk is smaller than 3%, and screening with either repeated stool tests or a single endoscopy if the risk is 3% or larger. A risk calculator can be used to estimate cancer risk.
The thesis recognizes the uncertainty in the knowledge base, the fine balance between benefits and harms of screening, and the diversity in people's values and preferences. For individuals making a choice of whether or not to screen, both agreeing to and declining colorectal cancer screening may be reasonable.
Additional information
Contact the research support staff.