The National Colorectal Cancer Screening Study – SCREESCO

The study was conducted as a multicentre trial involving 33 participating hospitals across 18 regions, with the aim of determining which screening method is most effective at preventing colorectal cancer and detecting it at an early stage. The study has also served as a means of gaining experience in the structured implementation of screening programs and ensuring the quality of colonoscopy services at participating centres.

Participating Regions

The SCREESCO study was carried out by the participating regions, with the Regional Cancer Centres in Collaboration serving as the steering group. The study has been coordinated and administered by the Regional Cancer Centre (RCC) Uppsala Örebro and has been reviewed and approved by the Regional Ethics Review Board in Stockholm.

The Stockholm and Gotland regions did not participate in the study, as they had already implemented colorectal cancer screening programs for their residents.

Participation in the Study

A total of 270,000 Swedish residents aged 59-62 years were included in the study. Participant recruitment took place over a five-year period and was completed in 2019. The final intervention was performed in December 2020. Following a careful recalculation of the study's statistical power, the follow-up period for evaluating the primary endpoints, cancer incidence and mortality, will conclude on 31 December 2030. Publication of the final results is expected approximately one year thereafter.

Participants were randomly selected using the Swedish Tax Agency's population register and randomized into one of the study's three groups: Group 1 received an invitation to undergo a colonoscopy directly. Group 2 was offered faecal testing on two occasions, two years apart. If a test result was positive (indicating a certain level of occult blood in the stool), the individual was invited to undergo a colonoscopy. Group 3 was not contacted and will passively be followed solely through national registers.

As the study was randomized, it was not possible for individuals to enrol in the study voluntarily.

Current Study Status

Participant recruitment and all study interventions have been completed. Results are being analysed continuously, and follow-up will continue until 31 December 2030. Registry-based data are being collected, including information on colorectal cancer diagnoses and colorectal cancer-related deaths. These data will be used in the final evaluation to determine whether there are differences between the study groups in colorectal cancer mortality.

Pending the final evaluation, several studies have been completed or are planned in a range of areas, including: Health economics; Patient experiences of screening; Colonoscopy quality; Microbiome research; Studies of FIT (faecal immunochemical testing); The impact of socioeconomic and geographic disparities.

References are available for some of the most important studies:

1. Forsberg A, Westerberg M, Metcalfe C, Steele R, Blom J, Engstrand L, et al. Once-only colonoscopy or two rounds of faecal immunochemical testing 2 years apart for colorectal cancer screening (SCREESCO): preliminary report of a randomised controlled trial. Lancet Gastroenterol Hepatol. 2022;7(6):513-21.
2. Sekiguchi M, Westerberg M, Ekbom A, Hultcrantz R, Forsberg A. Endoscopist Characteristics and Polyp Detection in Colonoscopy: Cross-Sectional Analyses of Screening of Swedish Colons. Gastroenterology. 2023;164(2):293-5 e4.
3. Westerberg M, Eriksson J, Metcalfe C, Lowbeer C, Ekbom A, Steele R, et al. Colonoscopy findings after increasing two-stool faecal immunochemical test (FIT) cut-off: Cross-sectional analysis of the SCREESCO randomized trial. J Intern Med. 2024; 296(2): 187-199
4. Stromberg U, Bonander C, Westerberg M, Levin LA, Metcalfe C, Steele R, et al. Colorectal cancer screening with fecal immunochemical testing or primary colonoscopy: An analysis of health equity based on a randomised trial. EClinicalMedicine. 2022;47:101398.
5. Westerberg M, Ludvigsson JF, Metcalfe C, Stromberg U, Blom J, Engstrand L, et al. Colonoscopy and fecal immunochemical testing versus usual care in diagnostic colorectal cancer screening: the SCREESCO randomized controlled trial. Nat Med. 2026;32(4):1278-85.