Screening can reduce colorectal cancer mortality by more than 40 percent

Colorectal cancer is one of the most common forms of cancer, with a favourable prognosis if detected early. Universal screening has been introduced throughout Sweden, meaning testing is offered to people aged 60–74 every two years.

ImagePanuwat Dangsungnoen

Colorectal cancer is among the most common forms of cancer and has a good prognosis when detected at an early stage. Population-based screening has been implemented throughout Sweden and offers testing every two years to people aged 60 to 74. Stockholm and Gotland were among the first regions to introduce routine screening, launching their programme in 2008. Researchers at Karolinska Institutet and Umeå University have now followed participants for up to 14 years to investigate how screening affects the risk of death from the disease. The study included more than 376,000 individuals.

“Population-based screening is a public health initiative that affects a large number of people. It is therefore important to evaluate its effectiveness,” says Håkan Jonsson, researcher at the Department of Epidemiology and Global Health at Umeå University and one of the scientists behind the study.

“A previous evaluation of the programme showed that people who received an invitation to screening had a 14 percent lower risk of dying from the disease. We can now show that the reduction in mortality is considerably greater among those who actually participate in the screening programme,” says Johannes Blom, senior consultant and associate professor at the Department of Clinical Research and Education, Södersjukhuset, Karolinska Institutet.

One in three do not participate in screening

The researchers compared individuals who were invited to screening between 2008 and 2012 with a control group that was either invited later or not invited at all. They used a statistical method to account for factors that can make the effect of screening difficult to estimate, including the fact that some people in the control group were later given the opportunity to participate and that some people who received invitations chose not to take part.

“Evaluating the effectiveness of screening can be challenging because of various sources of bias and the lack of individual-level data. In this study, the evaluation was planned from the outset by ensuring the availability of a control group and by collecting all the necessary individual-level data,” says Håkan Jonsson.

After accounting for these factors, receiving an invitation to screening was associated with a 26 percent lower risk of death from colorectal cancer, while active participation in screening was associated with a 43 percent lower risk of death.

“Although screening is offered free of charge and the test is simple to complete, around one-third of eligible individuals do not submit a sample. Our study highlights the importance of participating in colorectal cancer screening and shows that it can save lives,” says Johannes Blom.

This text was translated from Swedish using Microsoft Copilot. The text has been manually reviewed by the author prior to publication.