Colorectal Cancer Screening Significantly Improves Early Detection

New research indicates that colorectal cancer screening substantially increases the rate of early-stage diagnoses, potentially transforming how this deadly disease is managed. A study involving data from over 278,000 individuals aged 60, published in Nature Medicine, compared the effectiveness of colonoscopy and fecal immunochemical testing (FIT) against standard clinical care without screening.

The Importance of Early Detection

Colorectal cancer is a prevalent and often deadly malignancy. It is the third most common cancer in Sweden, with approximately 6,000 new cases diagnosed annually, and a leading cause of cancer-related deaths. Early detection and prevention are critical to improving patient outcomes.

The SCREESCO Study Design

The Swedish study, SCREESCO, initiated in 2014, investigated the efficacy of two distinct screening methods in reducing long-term mortality from colorectal cancer. Participants were randomly assigned to one of three groups:

• Primary Colonoscopy: Participants were directly invited for a colonoscopy.
• Fecal Immunochemical Test (FIT): Participants completed two FIT tests at home. A positive result (defined as 10 μg Hb/gr of stool) prompted a colonoscopy. This group underwent testing in year one and year three.
• Usual Care: Participants received standard medical care without screening intervention, serving as a control group.

Key Findings: Increased Early-Stage Detection

The results demonstrated that both screening methods – colonoscopy and FIT – led to a higher detection rate of early-stage colorectal cancer, particularly within the first two years of intervention. This is significant because early-stage cancers are generally more treatable. Researchers also noted the potential for detecting and removing adenomas, precursors to cancer, offering a preventive benefit.

Specifically, the FIT group showed a reduction in the development of colorectal cancer, with 0.61% developing the disease compared to 0.73% in the control group. This suggests a potential preventive effect through the removal of precancerous polyps.

Potential Risks and Ongoing Research

The study also examined potential adverse effects associated with increased colonoscopy rates. A slight increase in stomach and intestinal bleeding, as well as blood clots, was observed in the screening groups, particularly during the initial year when most colonoscopies were performed. Yet, these events were uncommon, and the overall mortality rate remained consistent across all groups.

Researchers are continuing to follow the study participants until 2030 to assess the long-term impact of these screening methods on colorectal cancer mortality.

Implications for Screening Programs

In Sweden, FIT-based screening has been offered to individuals aged 60-69 (and since 2020, 60-74) in certain regions since 2015. A national FIT-based screening program is being implemented nationwide, with full rollout planned for 2026.

Looking Ahead

The findings from the SCREESCO study offer encouraging evidence that colorectal cancer screening can significantly improve early detection rates and potentially reduce mortality. Continued research and widespread implementation of effective screening programs are crucial in the fight against this disease.