Swedish Colorectal Cancer Screening Trial: A Comprehensive Update on SCREESCO
Colorectal cancer (CRC) remains a significant cause of mortality in Sweden, with approximately 6,000 new cases diagnosed annually. A large-scale study, known as SCREESCO (Screening of Swedish Colons), is underway to determine the most effective methods for CRC screening within the Swedish population. This article provides a detailed overview of the trial’s design, implementation, and ongoing analysis, as of February 20, 2026.
Understanding the SCREESCO Trial
The SCREESCO trial, registered with ClinicalTrials.gov as NCT02078804, details a randomized controlled trial initiated in 2014. The study aims to evaluate the efficacy of different screening strategies in reducing CRC mortality and incidence. Eighteen of Sweden’s 21 counties are participating in the study, representing 74.5% of the national population where CRC screening was not previously offered.
Study Design and Participants
A total of 201,000 individuals aged 60 or turning 60 between 2014 and 2016 were randomly assigned to one of three arms:
- Primary Colonoscopy: Participants were invited for a single colonoscopy.
- Two Rounds of FIT (FIT×2): Participants received fecal immunochemical test (FIT) kits for two stool samples, with a second round of testing two years later. A positive FIT result (≥10 μg Hb/g feces) triggered a colonoscopy invitation.
- Usual Care (Control): Participants received no organized screening program.
Due to lower-than-expected participation in the primary colonoscopy arm (35%), an additional 77,280 individuals were randomized between 2017 and 2018 to either primary colonoscopy or the control group. This resulted in a total of 31,140 participants in the primary colonoscopy arm, 60,300 in the FIT×2 arm, and 186,840 in the control arms.
Intervention Procedures
Participants in the colonoscopy arm received a letter offering a scheduled colonoscopy. Those assigned to the FIT×2 arm received FIT kits with instructions for sample collection. All FIT analyses were performed at a central laboratory using an OC-Sensor DIANA automated analyzer. Research indicates that even low levels of FIT concentration can predict future CRC and advanced colorectal neoplasia (ACN) detection, suggesting the potential to enhance screening efficacy by combining results from both rounds.
Colonoscopies were performed at 33 hospitals by 146 endoscopists with specialized training.
Data Collection and Follow-up
Data on CRC diagnoses, adverse events, and deaths were collected through linkage with Swedish national registers, including the Cancer Register, Patient Register, Total Population Register, and Cause of Death Register. Follow-up continued until December 31, 2020, for the diagnostic phase of the trial. The primary endpoint of the study is CRC mortality at 15 years, with follow-up extending to December 31, 2030.
Safety and Adverse Events
Serious adverse events occurring within 30 days of colonoscopy were reported by endoscopy units and reviewed by a study nurse and a physician. Ongoing monitoring is facilitated through follow-up using healthcare registers.
Current Analysis and Future Reporting
The current analysis focuses on early CRCs and adverse events during the diagnostic phase of the trial, including data from the control arm. Researchers are assessing diagnostic yield (CRC diagnoses by stage), adverse events (cardiovascular and gastrointestinal), and overall mortality. The ultimate findings on CRC mortality will be reported in the final trial report in 2030.
Key Takeaways
- The SCREESCO trial is a large-scale, randomized controlled trial evaluating CRC screening strategies in Sweden.
- The study compares primary colonoscopy, two rounds of FIT, and usual care.
- Data are collected through linkage with national registers to track CRC diagnoses, adverse events, and mortality.
- The primary endpoint is CRC mortality at 15 years, with final results expected in 2030.
- Preliminary findings suggest that even low levels of FIT concentration can be predictive of future CRC risk.