• Claire L Harma, Thisuri Jayawardena, Ali G M Ismail, Vidit Lall, Priyanthi Kumarasinghe, Bastiaan De Boer, Christine Hemmings, Benhur Amanuel, Erin Kelty, Bob Mirzai, Belinda B Guo, Richard Allcock, Muna Salama, Spiro Raftopoulos, Ian Yusoff, Dev Segarajasingam, Wendy N Erber, and Hooi Ee.
• Department of Gastroenterology, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.
• Intern Med J. 2025 Feb 11.

BackgroundPost-colonoscopy colorectal cancer (PCCRC), defined as colorectal cancer (CRC) detected after a cancer-negative colonoscopy, represents a key quality indicator for CRC detection and prevention. While most PCCRC is attributed to missed lesions, few studies examine pathologic and molecular characteristics of PCCRC to assess for possible de novo cancer formation causing PCCRC.AimThe aim of this study was to identify cases of PCCRC where prior colonoscopy was adequate (A-PCCRC) versus inadequate (I-PCCRC) and compare both subtypes with spontaneous CRC (sCRC) in terms of patient factors, histopathology and molecular characteristics.MethodsThis was a 12-year retrospective population-based study using a data set from the Western Australian Cancer Registry between 2000 and 2011. A-PCCRCs were identified by excluding lesions likely missed due to procedural factors or incomplete prior resection at index colonoscopy performed within 3-36 months of cancer diagnosis. Histopathological review and next-generation sequencing were conducted on subsets of patients with A-PCCRC and sCRC. Statistical analysis included univariable and multivariable regression models and chi-squared and Wilcoxon rank sum tests.ResultsA total of 524 (3.81%) cases of PCCRC were identified out of 13 757 cases of CRC; 272 were A-PCCRC (1.98%) and 252 I-PCCRC (1.83%). Female sex, older age and proximal location were associated with A-PCCRC. Mutations in the PIK3CA gene were less common in A-PCCRC compared to sCRC.ConclusionA significant percentage of PCCRC occurred despite adequate prior colonoscopy. Missed sessile serrated lesions may contribute to many of these cases; however, further studies are required to examine possible de novo cancer as a cause of PCCRC that may involve unique biological pathways.© 2025 Royal Australasian College of Physicians.

4 keywords...

hide…