Colorectal cancer screening could reduce mortality by over 40%

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People who take part in screening for colorectal cancer may have as much as a 43% lower risk of dying from the disease, according to new estimates published in JAMA Network Open by researchers at Karolinska Institutet and Umeå University in Sweden. These findings are based on up to 14 years of follow-up data from the Stockholm–Gotland screening program.

Colorectal cancer is one of the most common forms of cancer, with a favorable prognosis if detected early. Universal screening has been introduced throughout Sweden, meaning testing is offered to people ages 60–74 every two years. Participants are sent a screening kit to their home address and asked to provide a stool sample, which is analyzed for small amounts of blood that are not visible to the naked eye. If blood is detected, further investigation is offered, usually in the form of a colonoscopy.

New study shows greater effectiveness

Stockholm and Gotland were early adopters, introducing routine screening as early as 2008. Researchers at Karolinska Institutet and Umeå University have now followed these individuals for up to 14 years to investigate the impact of screening on mortality rates.

"A previous evaluation of the program showed that those who received an invitation to screening had a 14% lower risk of dying from the disease," says Johannes Blom, senior consultant and associate professor at the Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, and the study's corresponding author. "We have now been able to show that mortality is significantly lower among those who actually take part in the screening."

Schematic Illustration of 6 Colorectal Cancer (CRC) Cases, Either Exposed to Screening (Study Group) or Not (Control Group). Credit: JAMA Network Open (2026). DOI:10.1001/jamanetworkopen.2026.29856

One-third do not take part in screening

The researchers compared those who were invited to screening between 2008 and 2012 with a control group who were either invited later or not at all. They used a statistical method to account for factors that could distort the results, such as some people in the control group being given the opportunity to participate later and some invited individuals not participating.

When these factors were taken into account, an invitation to screening was associated with a 26% lower risk of dying from colorectal cancer, while active participation was associated with a 43% lower risk.

"Although screening is offered free of charge and the test is simple to carry out, around a third of people do not submit a sample," Blom says. "Our study highlights the importance of taking part in colorectal cancer screening and shows that it can actually save lives."

Over 376,000 study participants

The study included 376,511 people, and during the follow-up period, 1,668 deaths from colorectal cancer were recorded. Some of the study's strengths include the large study population, the long follow-up period and the use of Swedish health registers. However, the researchers emphasize that the results are based on statistical adjustments for various types of bias, meaning that some uncertainties remain.

Publication details

Johannes Blom et al, Fecal Occult Blood Screening Outcomes Adjusted for Contamination Bias and Nonadherence, JAMA Network Open (2026). DOI: 10.1001/jamanetworkopen.2026.29856 jamanetwork.com/journals/jaman … /fullarticle/2853098

Journal information: JAMA Network Open

Key medical concepts

Screening for Colorectal CancerStool SampleColonoscopy

Clinical categories

OncologyCommon illnesses & PreventionPreventive medicine Provided by Karolinska Institutet Who's behind this story?

Gaby Clark

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