Colorectal cancer risk increased in patients with two types of polyps

By Melanie Hinze

A major Australian study has revealed that patients who present with both synchronous conventional adenomas and clinically serrated polyps (CSSPs) face a higher risk of developing advanced colorectal neoplasia than those with only adenoma.

Senior author, Dr Molla Wassie who is Senior Research Fellow at the College of Medicine and Public Health, Flinders University, Adelaide, said the study, published in Clinical Gastroenterology and Hepatology, highlighted the importance of vigilant surveillance in patients with these conditions.

The research included 8481 colonoscopy pairs from medical records from 5817 people (median age 61 years), with each pair comprising a prior and a follow-up colonoscopy. Individuals with synchronous adenomas and CSSPs were found to be 4.71 times more likely to develop advanced neoplasia (advanced precancerous neoplasia and/or colorectal cancer [CRC]) compared with those who had no neoplasia at their previous colonoscopy.

The study also found the risk of advanced neoplasia was 3.19 times higher in those with prior advanced synchronous adenoma and CSSP when compared with those with prior advanced adenoma only.

Dr Wassie emphasised the lack of prior evidence in this field and said this study demonstrated the high synergistic risk associated with the coexistence of these two polyp types.

‘This Australian study supports a surveillance interval of one to three years for patients with synchronous adenomas and CSSPs, depending on the number, size and histological features of the polyps,’ he said.

Patients with five or more mixed adenomas and clinically significant serrated polyps, or any mixed polyps with advanced features such as a size of 10 mm or greater or dysplasia, should be referred for colonoscopy within one year, according to Australian post-colonoscopy surveillance clinical guidelines.

The authors concluded that, ‘Patients with synchronous adenoma and CSSP may have concurrent adenoma-carcinoma and serrated pathways active, and are at higher risk of developing advanced neoplasia compared to those with only adenomas.’

Dr Wassie explained that both the adenoma-carcinoma and serrated pathways contributed to CRC development. When these pathways converged in a single patient, the risk of metachronous neoplasia increased substantially.

‘Timely detection and removal of neoplastic lesions through surveillance colonoscopy is therefore critical for effective CRC prevention,’ he said.

The study findings reinforced the importance of primary healthcare physicians recognising these risks early and making appropriate referrals.

‘Primary healthcare physicians can refer patients with synchronous adenomas and CSSPs for surveillance colonoscopy in accordance with Australia’s Clinical Practice Guidelines,’  Dr Wassie concluded.

Clin Gastroenterol Hepatol 2025; doi:10.1016/j.cgh. 2025.07.023.