Use of immunochemical fecal occult blood tests to extend surveillance colonoscopy in people with elevated colorectal cancer risk: A retrospective cohort study

M. Wassie, C. Cock, P. Bampton, J. Winter, G. Young , K. Simpson, H. Saluja, A. Chuang, R. Fraser, E. Symonds

Research output: Contribution to journalMeeting Abstractpeer-review


Background and Aim: Colonoscopic surveillance is undertaken at regular intervals (typically 3 or 5 years) to reduce the incidence of colorectal cancer (CRC) in people with an elevated risk (personal or family history of neoplasia). Pathology findings at index and each surveillance colonoscopy determine recall intervals. Due to coronavirus disease 2019, hospital services around the world have been limited, resulting in some surveillance colonoscopies being delayed beyond the recommended time frames. Previous studies suggest that delays to colonoscopy might increase the incidence of advanced neoplasia (advanced adenoma/CRC). However, it is possible that this risk could be reduced by ensuring that individuals are maintained in a CRC screening program with an immunochemical fecal occult blood test (FIT) in the interval between surveillance colonoscopies. Our aim was to determine whether risk of advanced neoplasia increases if surveillance colonoscopy is delayed in people with elevated CRC risk who perform and have a negative FIT result in the interval between colonoscopies.

Methods: We performed a retrospective cohort study using data from the Southern Cooperative Program for the Prevention of Colorectal Cancer on people at elevated risk because of family history or personal history of adenoma or CRC. People with at least two consecutive colonoscopies of a 3- or 5-year surveillance interval and who had at least one negative interval FIT result were included in the study. They were stratified based on a previous colonoscopy finding of advanced adenoma, non-advanced adenoma, or no neoplasia. People with early colonoscopies (3 months before the recommended due date), poor bowel preparation, previous CRC, or hereditary CRC syndromes were excluded from the study. Colonoscopy was defined as “delayed” if it did not occur within 6 months after the recommended recall interval and was further subdivided into delays of 6–12, 12–24, and >24 months. The incidence of advanced neoplasia was calculated for all groups. The relative risk (RR) and 95% confidence intervals estimated from a robust multivariable modified Poisson regression were used to assess the association between surveillance colonoscopy delay and risk of advanced neoplasia.

Results: A total of 1748 public hospital surveillance colonoscopies (in 1516 participants) were included in the analysis. More than half of the colonoscopies (56.86%, 994/1748) were delayed by at least 6 months because of system and/or patient factors. In people with delayed colonoscopies, the incidence of advanced neoplasia was higher in those with previous advanced adenoma (16.72%, 48/287) and previous non-advanced adenoma (15.23%, 37/243) compared with those with no neoplasia (6.25%, 29/464) (P < 0.001). However, relative to on-time colonoscopy, delay of surveillance colonoscopy was not associated with an increased risk of advanced neoplasia for people who had at least one negative interval FIT result, regardless of previous colonoscopy finding (previous advanced adenoma: RR, 1.01; 95% CI, 0.70–1.46; non-advanced adenoma: RR, 1.41; 95% CI, 0.85–2.33; and no neoplasia: RR, 0.96; 95% CI, 0.55–1.66) (Table 1).

Conclusion: In an elevated-risk cohort undergoing FIT screening between surveillance colonoscopies, delays to colonoscopy did not increase risk of advanced neoplasia. These results suggest that surveillance colonoscopy could be safely extended in people at elevated CRC risk by participating in FIT testing between colonoscopies within a surveillance program.

Table 1. Effect of colonoscopy delay on advanced neoplasia in elevated-risk surveillance participants who had at least one negative interval FIT result (n = 1748)
Original languageEnglish
Pages (from-to)16
Number of pages1
JournalJournal of Gastroenterology and Hepatology
Issue numberS3
Publication statusPublished - 2021


  • immunochemical
  • fecal
  • colonoscopy
  • colorectal cancer


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