A recent study has found that screening can help detect colorectal cancer at an earlier stage. The research, conducted by Uppsala University and Karolinska Institutet, involved more than 278,000 individuals aged 60 who were randomly assigned to one of two screening interventions or no screening (usual care). The findings were published in Nature Medicine.
Colorectal cancer is among the most common cancers worldwide. Early detection and prevention are considered important for lowering the risk of death from the disease. The Swedish SCREESCO study began in 2014 to assess how effective two different screening methods are at reducing long-term mortality from colorectal cancer.
Participants in the study were randomly divided into three groups: one group was offered a primary colonoscopy; another group was offered two faecal immunochemical tests (FIT), where participants provided stool samples and received a colonoscopy if any test was positive; and a control group received usual care without additional intervention. If precancerous changes were found during colonoscopies, patients received treatment according to standard guidelines. Participants’ health outcomes were monitored through registers until 2020.
At the end of the follow-up period, researchers observed fewer cases of advanced colorectal cancer in both intervention groups compared to the control group. The reduction was most pronounced in those who underwent FIT testing, with 0.61 percent developing colorectal cancer versus 0.73 percent in the control group.
"We can show that cases of advanced cancer tend to decrease towards the end of the period in the group that was randomised to provide stool samples for FIT. This could be evidence of a preventive effect of the screening, through the removal of the precursors to cancer," said Anna Forsberg, docent at Karolinska Institutet and lead author responsible for SCREESCO.
The study also looked into potential negative effects associated with increased colonoscopies. There was a small rise in stomach and intestinal bleeding as well as blood clots among these patient groups, particularly during the first year when most colonoscopies took place. However, such events remained rare, and overall mortality rates did not differ between groups.
Researchers plan to continue following participants until 2030 to determine whether these screening methods will reduce long-term mortality from colorectal cancer.
"This study gives us great hope that screening will also be shown to reduce mortality from colorectal cancer in both groups when the study is finally evaluated in about five years," said Anna Forsberg.
Screening with FIT has been offered every two years since 2015 for people aged 60–69 years in Region Stockholm and Region Gotland; this age range expanded up to 74 years starting from 2020. A national program using FIT-based screening began its rollout across Sweden in 2021 with plans for full implementation by 2026.
