Trial lecture - time and place
See trial lecture (note that both the trial lecture and disputation are conducted in Norwegian).
Adjudication committee
- First opponent: Professor Guri Skeie, University of Leeds
- Second opponent: Professor Ingvar Bosaeus, Sahlgrenska Universitetssjukhuset
- Committee chair: Associate Professor Anne-Marie Aas, University of Oslo
Chair of defence
Professor Magne Thoresen, University of Oslo
Principal supervisor
Associate Professor Siv Kjølsrud Bøhn, Norwegian University of Life Sciences
Summary
Growing evidence links obesity and type 2 diabetes to increased risk of colorectal cancer (CRC). Using data from two large US cohort studies of healthy women and men, we examined biological links between obesity, type 2 diabetes and CRC with emphasis on life-course exposures, including familiar predisposition.
Men with a family history of diabetes, mainly reflecting shared genetic factors, had increased risk of CRC compared to those without a family history, particularly those younger than 60 years. The results points towards shared genetic factors for diabetes and CRC.
Moreover, individuals with a heavy body shape trajectory had a more unfavorable biomarker profile in adult life, as indicated by higher C-peptide and lower insulin-like growth factor binding protein (IGFBP)-1 levels, than those who stayed lean throughout their life course. The unfavorable biomarker profile was mainly driven by attained body fatness, although weight gain in early-middle adulthood seemed to have an additional effect.
In addition to study the impact of lifestyle on CRC risk and pathogenetic mechanisms, we examined the nutritional status of patients diagnosed with CRC. A main focus was to validate assessment methods used to measure body composition. We demonstrate that bioelectrical impedance analysis (BIA), which is a simple and non-invasive method, is suitable to measure body composition and detect low muscle mass.
Moreover, we show that both chemotherapy and malnutrition are linked to increased levels of DNA damage in blood cells. Whether measurement of DNA damage could serve as a valuable tool in monitoring treatment response deserves further investigation.
In conclusion, the thesis contributes to increased knowledge about the biological mechanisms linking obesity and type 2 diabetes to CRC from a life-course perspective. The thesis also provides valuable knowledge about assessment methods in nutritional diagnosis and monitoring of CRC patients.
For further information
Contact the research support staff.