A routine blood test result that looks “too good” might actually be a warning sign for colon cancer in younger adults.
Story Snapshot
- New research links unusually low liver enzyme levels to a much higher chance of early-onset colorectal cancer in adults under 45.
- Epic Research found AST below 14 U/L tied to a 65% higher likelihood of diagnosis, and ALT below 14 U/L tied to a 68% higher likelihood.
- Higher enzyme levels showed the opposite pattern, linked to lower cancer likelihood, matching older studies on liver markers and cancer risk.
- Researchers stress this is an association, not proof that low enzymes cause cancer.
What The New Analysis Actually Found
Epic Research, an arm of the health records company Epic, looked at adults aged 18 to 44 getting their first colorectal cancer screening. People with an AST reading under 14 U/L had a 65% higher chance of an early-onset cancer diagnosis. Those with ALT under 14 U/L had a 68% higher chance. Both comparisons were measured against people with enzyme levels between 14 and 29 U/L, a range doctors normally consider healthy.
AST and ALT are enzymes made mostly in the liver. Doctors have used them for decades to check liver health. Normally, a low reading is nothing to worry about. It usually just means the liver isn’t under stress. This new data flips that assumption for younger patients getting screened for colon cancer, at least as a statistical pattern worth watching.
The Enzyme Pattern Runs Both Directions
The same Epic Research analysis found the reverse effect at the high end of the enzyme range. AST at 30 U/L or above was tied to a 22% lower likelihood of early-onset colorectal cancer. ALT at 30 U/L or above was tied to a 29% lower likelihood. That means the risk isn’t about enzymes being “bad” or “good” in general. It’s about where a patient falls on the scale, and low numbers are the ones raising flags here.
This isn’t the first time liver enzymes have shown up in cancer research. A large United Kingdom Biobank study tracking thousands of adults over time found that lower circulating levels of ALT, AST, and related liver markers were linked to higher colorectal cancer risk across the whole population, not just younger patients. Comparing the highest and lowest enzyme groups produced a risk ratio of roughly 0.6, meaning higher enzymes tracked with meaningfully lower cancer rates.
Why This Fits A Bigger Trend In Cancer Research
Colorectal cancer in adults under 50 has been climbing for years, and doctors still don’t have a single clear reason why. That gap has pushed researchers to mine ordinary medical records, like routine blood panels, for early clues that a standard screening test might miss. Liver enzyme levels are cheap, common, and already collected during most physicals, which makes this kind of signal appealing if it holds up under more testing.
Medical researchers quoted alongside the study were careful to note that an association is not the same as a cause. Low liver enzymes don’t create cancer, and having low AST or ALT is not a diagnosis or a reason to panic. Instead, doctors describe this as a potential piece of a larger puzzle, something that could someday help flag which younger patients deserve closer screening sooner.
What It Means For Screening Decisions Right Now
Colorectal cancer screening guidelines already dropped the recommended starting age to 45 in recent years, largely because of the rise in younger patients. This new enzyme data doesn’t change that guidance today, but it adds another data point doctors may eventually use to judge individual risk. For now, the practical takeaway for readers is simple: don’t ignore symptoms like blood in the stool, unexplained weight loss, or persistent stomach pain just because a blood panel looks otherwise normal.
More data beats less data when it comes to catching cancer early, especially in a generation seeing rates climb for reasons doctors still can’t fully explain. Families with a history of colorectal cancer, or anyone noticing new digestive symptoms, should talk to a doctor about screening rather than wait for research like this to become official guidance. Early detection remains the single biggest factor in survival, no matter what a lab report says.
Sources:
mindbodygreen.com, pubmed.ncbi.nlm.nih.gov, epicresearch.org
