ENCODER: Liquid Biopsy for Young-Onset Colorectal Cancer- Gastroenterology Feb.26

Introduction

Early-onset colorectal cancer (EOCRC), defined as CRC diagnosed before the age of 50, is rising globally and has become a leading cause of cancer-related death in young adults, particularly men. Despite this, screening uptake in younger populations remains poor, largely because current strategies rely on age thresholds and invasive tests.

This study asks a critical question:

Can a simple blood-based test help identify EOCRC early—before symptoms or advanced disease develop?

The clinical problem

Most EOCRC cases are diagnosed outside traditional screening programs, often at more advanced stages. Colonoscopy is effective but impractical as a population-wide tool in young adults. Stool-based tests may help, but still suffer from limited acceptance.

A highly accurate, noninvasive blood test could dramatically change early detection and screening strategies for this growing at-risk population.

What the ENCODER study did:

Large international, multicenter study across the US, Europe, and Japan.

Identified a panel of 6 circulating biomarkers, including exosome-derived small RNAs, using advanced sequencing techniques.

Built a machine-learning model to distinguish EOCRC from non-cancer controls.

Tested the model in an independent external cohort, ensuring real-world robustness.

Evaluated biomarker changes before and after surgical resection to assess biological relevance.

Key findings clinicians should understand

1) High accuracy for EOCRC detection

The liquid biopsy reliably distinguished EOCRC patients from healthy controls across multiple cohorts and countries, demonstrating strong generalizability.

2) Works even in very young adults

Remarkably, the test performed well even in individuals aged 20–35 years, a group in whom CRC is often least suspected.

3) Strong performance in early, screen-relevant stages

The assay was particularly effective for stage I–III EOCRC, the window where early detection has the greatest impact on survival.

4) Detects advanced precancerous lesions

The test showed moderate ability to detect high-grade dysplasia, suggesting potential utility not only for cancer detection but also for interception.

5) Biomarkers track with tumour removal

Liquid biopsy signals dropped rapidly after surgery, supporting a direct biological link to tumour burden and raising the possibility of future use in surveillance or minimal residual disease monitoring.

How this could fit into practice

This study does not suggest replacing colonoscopy. Instead, it points toward a complementary screening strategy, particularly for:

Young adults below the standard screening age,

individuals reluctant to undergo invasive testing, and

populations with rising EOCRC incidence but low screening participation.

A blood-based test could serve as a first-line risk stratification tool, identifying individuals who should proceed to diagnostic colonoscopy.

Key limitations to keep in mind

This was a case–control design, not a population screening trial.

Performance in real-world, low-prevalence screening settings remains to be tested.

Cost-effectiveness, implementation logistics, and comparison with stool-based tests are still unknown.

Bottom-line takeaway:

The ENCODER study provides compelling proof-of-concept that an exosome-based liquid biopsy can accurately detect early-onset colorectal cancer—even in very young adults—and may become a valuable adjunct to future screening strategies.

One-line GastroAGI takeaway

A simple blood test could help close the screening gap for early-onset colorectal cancer.