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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 Linda Rabeneck, University of Toronto, Canada
- Second opponent: Professor Eyvind Paulssen, UiT The Arctic University of Norway,
- Third member and chair of the evaluation committee: Associate professor Stephan Brackmann, University of Oslo
Chair of the Defence
Associate Professor Knut Magne Augestad, University of Oslo
Principal Supervisor
Associate Professor Øyvind Holme, University of Oslo
Summary
Colorectal cancer is the third most common cancer in the world, and the incidence rate in Norway is one of the highest in the world. Recently, the awareness of cancer cases occurring after a colonoscopy (post-colonoscopy colorectal cancers, PCCRC) has increased. This thesis aimed to investigate the quality of colonoscopy in Norway, and more specifically the rate of incompletely removed colorectal polyps that could cause PCCRC.
First, all board-certified gastroenterologists in Norway were invited to answer a questionnaire on polypectomy techniques. 40% of the respondents used inadequate polypectomy techniques.
The next step was to investigate the quality of the polypectomies. A quality study was conducted at four hospitals in Norway, where polyps found at colonoscopy were removed at the endoscopists own request, and biopsies were taken from the resection margins to look for residual polyp tissue. The results showed that 14.6% of polyps <20mm were incompletely removed, and in regression analyses we found that polyp location in the right colon and sessile serrated polyp histology were associated with incomplete polyp resection.
The last study was a RCT where polypectomy of polyps <10 mm with (hot snare) and without (cold snare) electrocautery was compared to investigate the incomplete polyp resection rate. Biopsies were taken from the resection margins after polypectomy to look for residual polyp tissue. The incomplete resection rate was 7.4% and 10.7%, respectively, for the hot and cold snare groups. The study was designed as a non-inferiority study, and we could not demonstrate non-inferiority for the cold snare compared to the hot snare, but there were no statistically significant differences between the groups.
In conclusion, there is still used inadequate polypectomy techniques and the incomplete polyp resection rate of 14.6% is substantial, thus more training of endoscopists is needed. Cold snare was not non-inferior to hot snare but is considered a safe choice for removal of the smallest polyps.
Additional information
Contact the research support staff.