Researchers from Flinders University and Flinders Medical Centre, reviewing more than 8,400 colonoscopy records, reported that people found to have both adenomas and serrated polyps had up to a fivefold higher risk of developing advanced precancerous colorectal changes at follow-up than those with only one polyp type.
Bowel cancer, also known as colorectal cancer, remains a major health concern in Australia. Flinders University said it is the country’s second leading cause of cancer death and the fourth most frequently diagnosed cancer.
Many colorectal cancers begin as polyps—growths on the bowel’s inner lining that are often benign. But some polyps, including adenomas and certain serrated polyps, can develop into cancer over time.
In a study published in Clinical Gastroenterology and Hepatology, researchers from Flinders University and Flinders Medical Centre reviewed more than 8,400 colonoscopy records and reported a markedly higher risk when the two polyp types were found together. The analysis found that people with both adenomas and serrated polyps—described by the researchers as “synchronous lesions”—had up to a fivefold higher risk of advanced precancerous colorectal changes at follow-up compared with people who had only one of the two polyp types.
“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,” said Dr. Molla Wassie, the study’s lead author and a researcher at the FHMRI Bowel Health Service.
The team also reported that the overlap was common: nearly half of patients with serrated polyps also had adenomas.
The study adds to broader evidence that colorectal cancer can develop through different biological pathways. Dr. Wassie said the findings support growing international evidence that adenomas and serrated polyps may represent distinct pathways that can be active at the same time. The researchers also said the results suggest serrated polyps may progress to cancer more quickly than adenomas, reinforcing the role of timely detection and appropriate follow-up colonoscopy.
“Polyps become more common as we age, but the key is catching and removing them early,” Wassie said, adding that people who have had both types of polyps should be especially careful to keep up with their surveillance schedules.
The Flinders release encouraged people over 45 and those with a family history of bowel disease to speak with a general practitioner or consult Australia’s National Bowel Cancer Screening Program about screening options.
According to the Flinders release, the work was linked to the Southern Cooperative Program for the Prevention of Colorectal Cancer (SCOOP), and Wassie is supported by an NHMRC Investigator Grant (#2009050).
