Early-onset colorectal cancer (CRC) is on the rise globally, and more than half of cases are now diagnosed before age 45 — the point at which routine screening typically begins. A new study suggests that biological age, calculated from nine standard blood markers, could be a powerful tool for identifying younger adults at elevated risk long before symptoms appear.

Researchers analyzed data from nearly 200,000 Korean adults under 50, tracking them for a median of 7.7 years. Using the "phenotypic age" algorithm — which factors in markers like albumin, glucose, C-reactive protein, and white blood cell count alongside chronological age — they found that those whose biological age ran 2+ years older than their peers faced significantly higher CRC risk. Notably, the association was specific to colon adenocarcinoma; rectal adenocarcinoma and colorectal neuroendocrine tumors showed no significant link.

By the Numbers:

• 93% higher risk of early-onset colorectal adenocarcinoma in the accelerated aging group vs. the reference group (HR, 1.93)
• 7% increased risk for every 1-unit rise in biological age acceleration
• 2.32x higher risk specifically for colon adenocarcinoma (HR, 2.32)
• 127 participants developed early-onset colorectal adenocarcinoma during follow-up
• No significant association found for rectal adenocarcinoma or colorectal neuroendocrine tumors

Why it matters: Routine blood tests are already part of standard care — this research suggests they could do double duty as an early warning system for colorectal cancer in younger patients, potentially reshaping how clinicians assess risk before the standard screening age.