Colorectal Cancer Screening Cuts Death Risk by 43% for Participants, Swedish Study Finds

People who took part in colorectal cancer screening had 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.

The findings draw on up to 14 years of follow-up data from the Stockholm-Gotland screening programme, which began in 2008. Sweden offers people aged 60 to 74 a free at-home screening kit every two years; participants provide a stool sample that is checked for tiny amounts of blood not visible to the naked eye, with a colonoscopy offered if blood is found.

The researchers compared people invited to screening between 2008 and 2012 with a control group invited later or not at all, adjusting statistically for factors such as later eligibility and non-participation. After these adjustments, receiving an invitation to screening was associated with a 26% lower risk of dying from colorectal cancer, while actually participating was associated with a 43% lower risk. An earlier evaluation of the programme had found only a 14% lower risk among those invited.

"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," said Johannes Blom, senior consultant and associate professor at the Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, and the study's corresponding author. "Our study highlights the importance of taking part in colorectal cancer screening, and shows that it can actually save lives."

The study followed 376,511 people and recorded 1,668 deaths from colorectal cancer over the follow-up period; it was funded by the Swedish Cancer Society, the Swedish Research Council and Region Stockholm.