Response to Larsen et al.

We are grateful for the detailed response from Larsen et al., which provides us with insights to further clarify the methodology that was chosen for our study on interval post-colonoscopy colorectal cancer (iPCCRC) in a fecal immunochemical test (FIT)-based screening program [11].

First, we acknowledge that the age distribution in our sample was skewed toward the older age groups, which will have affected our results; CRC incidence is higher in older age groups and therefore iPCCRC risk is expected to be higher. Nonetheless, the cancers detected in the older age groups should still be classified as post-colonoscopy CRCs according to the World Endoscopy Organization consensus statement [22]. In addition, a negative colonoscopy should provide justified reassurance to individuals, irrespective of age.

Second, as colonoscopy registration is fallible, all negative colonoscopies with discrepant follow-up followed by an iPCCRC diagnosis and a random sample of 250 colonoscopies with discrepant follow-up without iPCCRC were extensively verified using pathology reports and excluded when the definition of a negative colonoscopy was not met. As described in the methods, we estimated the total number of negative colonoscopies based on the rate of negative colonoscopies in the random sample. The inquiry for an explanation of why iPCCRCs were relatively more common in the group with discrepant follow-up recommendation is valid, yet in our opinion does not undermine the conclusion of our study.

Finally, there is indeed an immortal time period after a positive FIT result. However, this period of 6 months is recommended in the aforementioned consensus statement, and our analyses and results are reported in line with this statement [22]. The 6-month period allows for delays in the diagnosis of screen-detected cancers, for example due to repeat procedures following an inadequate colonoscopy. In that respect, our estimation of the risk of iPCCRC is conservative, but consistent with the guidelines.

Publikationsverlauf

Artikel online veröffentlicht:
30. Juli 2024

• References

• 1 Van de Schootbrugge-Vandermeer HJ, Kooyker AI, Wisse PHA. et al. Interval post-colonoscopy colorectal cancer following a negative colonoscopy in a fecal immunochemical test-based screening program. Endoscopy 2023; 55: 1061-1069
• 2 Rutter MD, Beintaris I, Valori R. et al. World Endoscopy Organization consensus statements on post-colonoscopy and post-imaging colorectal cancer. Gastroenterology 2018; 155: 909-925.e3