Research projects

The bowel cancer screening pilot study is a pilot project on screening for colorectal cancer, i.e. cancer in the colon and rectum. It is a randomized trial on colorectal screening that compares one-time sigmoidoscopy with a fecal occult blood test every other year.
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The study was initiated in 2012 and the examinations will conclude in 2024. This is the first time that fecal sample screening has been tested in Norway.

So far, about 25 original articles have been published, 4 doctoral theses have been completed, and several are underway. The research has provided new insights and contributed to the planning of the national Colorectal Screening Program.

Participation in the pilot project

For screening to be effective, it's important that participation rates are high. In the Colorectal Screening Pilot, we have researched factors that can influence attendance for colorectal screening.

Berstad P, Schult AL, Hoff G et al. (2023)
Social disparities in the preliminary project for colorectal cancer screening (article in norwegian).
Tidsskrift Norsk Legeforening

Bhargava S, Botteri E, Berthelsen M et al.(2023)
Lower participation among immigrants in colorectal cancer screening in Norway.
Front Public Health

Kirkøen B, Berstad P, Hoff G et al. (2023)
Type and severity of mental illness and participation in colorectal cancer screening.
Am J Prev Med, 64:76-85

Botteri E, Hoff G, Randel K et al. (2022)
Characteristics of non-participants in a randomized colorectal cancer screening trial comparing sigmoidoscopy and faecal immuochemical test.
Internat J Cancer, 2022;80:102244.

Berthelsen M, Berstad P, Randel K et al.(2022)
The impact of driving time on participation in colorectal cancer screening with sigmoidoscopy and faecal immunochemical blood testing.
Cancer Epidemiol, 80:102244.

Lifestyle and colorectal cancer

A healthy lifestyle can reduce the risk of colorectal cancer. There are several projects researching this in the Bowel Cancer Screening Pilot. Additionally, Markus Knudsen has completed a PhD on this topic (see further down the page).

Kværner ASBirkeland EVinberg E et al. (2023)
Associations of red and processed meat intake with screen-detected colorectal lesions.
Br J Nutrition 2023;129:2122-32 

Kværner AS, Andersen A, Henriksen H et al. (2023)
Associations of the 2018 World Cancer Research Fund/American Institute of Cancer Research (WCRF/AICR) cancer prevention recommendations with stages of colorectal carcinogenesis.
Cancer Med

Knudsen MD, Kværner AS, Botteri E et al. (2022)
Lifestyle predictors for inconsistent participation to fecal based colorectal cancer screening.
BMC Cancer, 22:172

Kværner AS, Knudsen MD, Hjartåker A et al. (2021)
Kost, livsstil og tarmscreening.
Norsk Tidsskrift for Ernæring, 3, s.12-18.

Knudsen MD, Botteri E, Holme Ø et al. (2021)
Association between lifestyle and site-specific colorectal lesions in screening with faecal immunichemical test and sigmoidoscopy.
Dig Liver Disease, 53:353-9 x.

Knudsen MD, Hjartåker A, Olsen M et al. (2018)
Improving cancer preventive behaviors: A randomized trial of tailored feedback in colorectal cancer screening.
Eur J Cancer Prev., Jul;27(4):316-322.

Colonoscopy quality

High-quality examinations yield the best screening effectiveness. In the Bowel Cancer Screening Pilot, resident physicians have been trained to perform sigmoidoscopies and colonoscopies. We have examined the quality of these examinations.

Schult AS, Hoff G, Botteri E et al. (2023)
CS quality improvement after initial training.
Endoscopy Internat Open. E117-127.

Ongoing PhD projects

Øyvind Rognstad
Adverse events after colonoscopy in colorectal cancer screening

Sara Nafisi
Repurposing medicines: new alternatives for the prevention and treatment of colorectal cancer.

Nafisi S, Randel K, Støer N et al. (2023)
Association between use of low-dose aspirin and detection of colorectal polyps and cancer in a screening setting.
Digestive and Liver Disease, 1126-1132

Sara Ribe
Colorectal cancers after screening or endoscopic examination of the large bowel.

Ribe S, Botteri E, Løberg M et al. (2023)
Impact of time between faecal immunochemical tests in colorectal cancer screening on screening results: A natural experiment
International Journal of Cancer, 152:1414-24  

Completed PhD projects

Benedicte Kirkøen (2017)
Does colorectal cancer screening cause psychological harm? Results from the randomized trial “Bowel Cancer Screening in Norway".
University of Oslo 2017. ISBN 978-82-8377-125-1 

Benedicte Kirkøen and colleagues have studied participants' experiences of colorectal cancer screening in the pilot for the national Colorectal Screening Program. The researchers measured participants' anxiety, depression, and health-related quality of life before and after screening. A false-positive screening result did not lead to increased anxiety, while a negative screening result showed a slight decrease in anxiety, indicating that participants were temporarily relieved.

Participants who underwent fecal sample testing did not experience any other psychological reactions compared to those who were not invited. However, in the colonoscopy group, it was observed that those who were anxious before screening experienced increased anxiety from participating.

The researchers also measured acceptance of the two different screening tests. Almost all participants would undergo screening again, but more were willing to repeat the fecal sample test than the colonoscopy. Women were less willing to repeat the colonoscopy compared to men because more women experienced pain during the procedure.

Overall, the findings suggest that colorectal cancer screening is well accepted among Norwegian participants, but there are fewer psychological reactions and higher acceptance for screening with the fecal sample test.

Kirkøen B, Berstad P, Botteri E et al. (2017)
Acceptability of two colorectal cancer screening tests: pain as a key determinant in sigmoidoscopy.
Endoscopy, 49(11): 1075-1086

Kirkøen B, Berstad P, Botteri E et al. (2016)
Psychological effects of CRC screening: Participants vs/ individuals not invited.
World Journal of Gastroenterology, Nov 21; 22(43): 9631–9641.

Kirkøen B, Berstad P, Botteri E et al. (2016)
Do no harm: no psychological harm from colorectal cancer screening
British Journal of Cancer, Mar 1; 114(5): 497–504.

Markus Dines Knudsen (2017)
Lifestyle and colorectal cancer screening by fecal immunochemical test and sigmoiodoscopy in a Norwegian pilot study.
University of Oslo. ISBN 978-82-8377-129-9

In his doctoral thesis, Markus D. Knudsen has demonstrated that participation in screening for colorectal cancer does not have an adverse effect on lifestyle, as assessed by smoking habits, alcohol consumption, physical activity, diet, and body weight one year after screening.

However, it was found that individuals with unhealthy lifestyle habits, compared to those with healthy lifestyle habits, were less likely to participate in subsequent screening rounds with fecal occult blood testing. Furthermore, it was shown that participants who met the most health recommendations had a lower risk of being diagnosed with colorectal cancer or precursors to it in the screening examination, compared to those who met few or no health recommendations.

Knudsen MD, Hjartåker A, Olsen M et al. (2018)
Changes in health behavior 1 year after testing negative at a colorectal cancer screening: a randomized-controlled study
European Journal of Cancer, 27(4):316-322.

Knudsen MD, Hjartåker A, Olsen M et al. (2017)
Lifestyle predictors for non-participation and outcome in the second round of faecal immunochemical test in colorectal cancer screening
Br J Cancer, 117:461-9.

Knudsen MD, de Lange T, Botteri E et al. (2016)
Favorable lifestyle before diagnosis associated with lower risk of screen-detected advanced colorectal neoplasia.
W J Gastroenterol, 22:6276-86  

Kristin Ranheim Randel (2021)
Faecal testing or sigmoidoscopy for colorectal cancer screening? Baseline results from a randomized trial.
University of Oslo. ISBN 978-82-8377-859-5

The aim of Kristin R. Randel's doctoral thesis was to compare attendance, findings during screening, and adverse events between the two screening methods. The thesis also explored findings at different threshold levels for fecal occult blood testing and findings among participants using anticoagulant medications.

The results showed higher participation rates and detection of colorectal cancer and advanced precursors for colorectal cancer after three rounds of fecal testing compared to sigmoidoscopy screening. The occurrence of serious complications during colonoscopy following a positive fecal test or positive sigmoidoscopy was as expected and not different between the two methods. If the threshold for a positive fecal test is raised to levels used in some European countries, there would be a need for fewer colonoscopies, but significantly fewer advanced precursors and cases of cancer would be detected. The use of anticoagulant medications was associated with lower positive predictive values for cancer and advanced precursors in participants with a positive fecal test.

Randel KR, Schult AL, Botteri E et al. (2021)
Colorectal cancer screening with repeated fecal immunochemical test versus once-only sigmoidoscopy: baseline results from a large randomized trial.
Gastroenterology, 160:1085-96  

Randel KR, Botteri E, Romstad KM et al. (2019)
Effects of oral anticoagulants and aspirin on performance of fecal immunochemical tests in colorectal cancer screening.
Gastroenterology, 156(6):1642-1649

​Anna Lisa Schult (2022)
Performance of two screening tests and barriers to colorectal cancer screening
University of Oslo. ISBN 978-82-8377-992-9

Anna Lisa Schults's doctoral thesis showed that participation rates in screening with fecal occult blood testing were higher than with sigmoidoscopy screening. More cases of colorectal cancer and advanced precursors were detected through fecal testing screening, and most cases of cancer and potential precursors were found in screening participants without symptoms. Women who received analgesics before colonoscopy reported fewer painful colonoscopies than women treated with analgesics as needed.

The results highlight the importance of encouraging asymptomatic individuals to participate in screening programs. It was also demonstrated that analgesics should be offered to women before the colonoscopy procedure starts. Optimized pain relief during colonoscopy may impact the reputation of screening and thus increase participation rates and the effectiveness of endoscopic screening.

Schult AL, Botteri E, Hoff G et al. (2021)
Women require routine opioids to prevent painful colonoscopies: a randomised controlled trial.
Scand J Gastroenterology, 56(12):1480-1489.

Schult AL, Botteri E, Hoff G et al. (2021)
The role of bowel symptoms in colorectal cancer screening participants: a cross-sectional study.
BMJ Open, 

Randel KR, Schult AL, Botteri E et al. (2021)
Colorectal cancer screening with repeated fecal immunochemical test versus once-only sigmoidoscopy: baseline results from a large randomized trial.
Gastroenterology, 160:1085-96