Blood-Based Tests Show Promise for Detecting Colorectal Cancer, But Follow-Up Rates Need Improvement

Recent research conducted by investigators at UCLA Health's Jonsson Comprehensive Cancer Center highlights the potential of blood-based screening tests for colorectal cancer. These tests offer a noninvasive and convenient alternative to traditional screening methods like colonoscopy or stool-based tests. The study analyzed data from over 6,000 individuals aged 45 and older who underwent a blood test called Shield from Guardant Health between 2022 and 2024. Among these, 452 individuals received abnormal results, and the research focused on how many completed a follow-up colonoscopy within six months.

The findings revealed that only 49% of patients with abnormal blood test results proceeded to have a colonoscopy within six months, and just 56% did so within the entire two-year period. Follow-up colonoscopy is a critical step to confirm or rule out colorectal cancer or pre-cancerous conditions, enabling early intervention. The low follow-up rates mirror those observed with stool-based screening tests but remain insufficient for timely diagnosis and effective treatment.

The study also found disparities in follow-up completion based on insurance type, with individuals enrolled in Medicare Advantage less likely to undergo follow-up compared to those with private insurance. Conversely, having fewer health conditions increased the likelihood of timely follow-up. Interestingly, race and ethnicity did not significantly influence follow-up adherence in this cohort, differing from some prior research.

Colorectal cancer is the second leading cause of cancer-related deaths in the United States. Early detection through regular screening can significantly improve survival rates. While blood-based screening tests provide a more accessible option, their success largely depends on patients completing follow-up procedures such as colonoscopy after abnormal results.

Researchers conducted a retrospective analysis using medical claims data from over 6,000 patients, focusing on the 452 with abnormal blood test results. The study's senior authors, Dr. Folasade May and Dr. Timothy Zaki from UCLA, emphasize that blood-based screening holds promise but underscores the need for better strategies to ensure patients follow through with necessary diagnostic procedures to truly impact cancer outcomes.

Source: https://medicalxpress.com/news/2025-07-blood-potential-colorectal-cancer-falls.html