First on CNN: Blood Tests May Offer Clues to Early Colorectal Cancer
Sandego.net – First on CNN: Routine blood work may hold clues that could help researchers better understand colorectal cancer diagnosed before age 45. An analysis from Epic Research found that younger adults with lower levels of two liver enzymes, AST and ALT, were more likely to later receive an early-onset colorectal cancer diagnosis than peers with higher levels.
The findings do not mean that low enzyme levels diagnose cancer or that screening recommendations should change. Instead, the research identifies a pattern that may help scientists explore why colorectal cancer cases are increasing among younger adults.
An unexpected signal in common blood tests
AST, or aspartate transaminase, and ALT, or alanine transaminase, are enzymes frequently included in liver-related blood testing. Doctors often pay attention to elevated results because they can be associated with liver inflammation, injury, infection or disease.
That made the association found in the Epic Research analysis especially notable. Released Wednesday, the analysis has not yet been published in a peer-reviewed journal. It shows a relationship between lower AST and ALT values and cancer diagnoses, but it does not prove that either enzyme level causes colorectal cancer.
“The direction was a little counterintuitive. Clinically, we tend to watch for high liver enzymes, so seeing that low AST and ALT were associated with a higher likelihood of early-onset colorectal cancer stood out,” said Kersten Bartelt, a clinician and researcher at Epic Research who worked on the analysis.
Researchers also looked at routinely collected results including triglycerides, cholesterol and potassium. Those values did not show an association with colorectal cancer occurring at younger ages.
Low AST and ALT are not a cancer diagnosis
First on CNN reporting on the analysis underscores an important limit: a single blood-test result cannot predict whether someone has colorectal cancer. Low AST or ALT levels alone do not mean a person needs a colonoscopy before the recommended screening age, and patients should not try to raise the numbers themselves.
“AST and ALT aren’t values we’d advise anyone to try to raise,” Bartelt said. “And nothing in our study suggests that changing them would change a person’s cancer risk.”
Lower levels may reflect broader health factors, such as muscle mass, nutritional status or frailty. Those explanations remain areas for future study, not conclusions established by the analysis.
“They likely reflect underlying physiology like muscle and nutritional status, so the focus should be on overall health in partnership with your clinician, not on moving a single lab number,” Bartelt said.
Why colorectal cancer before age 45 is drawing attention
Colorectal cancer is now the leading cause of cancer death in the United States among people younger than 50. Researchers have not fully explained the increase in diagnoses among younger adults.
Family history and inherited conditions can increase risk, but they do not account for every case. Experts have also examined obesity, metabolic health, diet, physical inactivity, changes in the gut microbiome, antibiotic exposure and delays in recognizing symptoms in younger patients.
“The broader conversation surrounding early-onset colorectal cancer has focused on family history and genetics, obesity and metabolic health, diet, physical inactivity, the microbiome, antibiotic exposures and delays in recognizing symptoms in younger patients. However, none of these factors fully explains the increase in cases,” said Dr. Marc Fenster, a gastroenterologist at Episcopal Health Services in New York who was not involved in the analysis.
Fenster said the findings may broaden research into whether routine metabolic and nutritional markers can offer useful signals. However, low AST and ALT levels should not be treated as established colorectal cancer risk factors.
FAQ: What should patients do?
Should I worry if my AST or ALT level is low?
Not based on this finding alone. Low results can occur for many reasons and do not diagnose colorectal cancer. Discuss results with a clinician who can consider your medical history, symptoms and other test findings.
Does this research change colorectal cancer screening guidance?
No. The analysis does not change current screening recommendations. People should follow guidance from their health care professional, especially if they have a family history of colorectal cancer or inherited risk factors.
What symptoms should I discuss with a doctor?
Persistent changes in bowel habits, blood in the stool, unexplained weight loss, ongoing abdominal pain or unusual fatigue deserve medical attention. Symptoms can have many causes, but timely discussion with a clinician is important.
First on CNN, the central message from researchers is that routine blood tests may provide another avenue for investigation—not a new diagnostic test or a replacement for appropriate screening and medical care.
