Scientists Uncover Hidden Cancer Risk in Common Bowel Growths

A large Australian study has uncovered new evidence linking the presence of two different types of bowel polyps to a substantially higher risk of advanced pre-cancerous changes.

A routine colonoscopy can uncover tiny growths that most people never feel. But new research from Flinders University and Flinders Medical Centre suggests a specific combination of these growths may signal a much higher risk of dangerous changes that can lead to colorectal cancer.

In Australia, colorectal cancer is the second deadliest cancer and the fourth most commonly diagnosed. Many cases begin with polyps, which are usually benign bumps on the bowel lining that can be removed before they cause harm. The concern is that two particular polyp types, adenomas and serrated polyps, can sometimes evolve toward cancer through different biological routes.

Study Examines Combined Polyp Risk

The research team reviewed more than 8,400 colonoscopy records and found a striking pattern. People who had both adenomas and serrated polyps were up to five times more likely to develop advanced precancerous changes than those who had only one type.

“Polyps are common and usually harmless, but when both types appear together—what we call synchronous lesions—the risk of serious bowel disease or cancer rises sharply,” says Dr. Molla Wassie, lead author and researcher at the FHMRI Bowel Health Service.

The researchers also found that nearly half of patients diagnosed with serrated polyps also had adenomas. This suggests that this higher risk combination may be more common than previously recognized.

“This is one of the largest studies of its kind,” says Dr. Wassie.

“Our findings support growing international evidence that these two types of polyps may represent separate cancer pathways that can be active at the same time—making early detection and regular monitoring even more important.”

Evidence for Distinct Cancer Pathways

The study indicates that serrated polyps may develop into cancer more quickly than adenomas. This finding highlights the importance of surveillance guidelines that reflect a patient’s specific risk profile.

“Polyps become more common as we age, but the key is catching and removing them early,” says Dr. Wassie.

“If you’ve had both types of polyps, it’s especially important to stay on top of your colonoscopy schedule.”

If you’re over 45 or have a family history of bowel issues, talk to your GP or visit the National Bowel Cancer Screening Program to learn more.

Reference: “Risk of Advanced Colorectal Neoplasia at Follow-up Colonoscopy After Synchronous Adenoma and Clinically Significant Serrated Polyp” by Geraldine Laven-Law, Erin L. Symonds, Kalindra Simpson, Michelle Coats, Mahinda De Silva, Paul Hollington, Charles Cock and Molla Mesele Wassie, 5 August 2025, Clinical Gastroenterology and Hepatology.
DOI: 10.1016/j.cgh.2025.07.023

The Southern Cooperative Program for the Prevention of Colorectal Cancer program (SCOOP) was first funded by the National Demonstration Hospitals Program Phase 3. Dr. Wassie is supported by a NHMRC Investigator Grant (#2009050).

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