The results reported by Van de Schootbrugge-Vandermeer et al. might not support their conclusions

Van de Schootbrugge-Vandermeer et al. [11] found that the 2.5-year cumulative colorectal cancer (CRC) risk among fecal immunochemical test (FIT)-positive individuals with a screen-derived negative colonoscopy was similar to the 2-year cumulative risk among FIT-negative individuals. They concluded that the FIT screening interval may need to be reduced after a negative colonoscopy. We have concerns about the following points.

Schootbrugge-Vandermeer et al. included screening participants aged 55–76 years in their study group. The higher risk of CRC among the oldest participants might have overestimated the true CRC risk among those that will be reinvited for FIT screening. It would be very interesting to know the cumulative CRC risk among residents that will actually be reinvited to FIT screening (i.e. those aged 55–73 years).

The authors included not only individuals with a correct registration of a negative colonoscopy (i.e. an adenoma score of zero and referral back to the screening program in 10 years), but also some individuals with incorrect registration (e.g. they included 5561 individuals with a registered negative colonoscopy and a discrepant recommendation for referral back to the screening program). These 5561 individuals constituted less than 16% of all participants but contributed more than 33% of all CRC cases. Conclusions on the correct screening interval should not be made based on this group as there might have been reasons for the discrepant recommendation for early screening.

Finally, we are concerned about the study design including a CRC risk-free period of 6 months in the study group. We understand the need for this 6-months risk-free period, but it will necessarily lead to immortal time bias, as the FIT-negative group does not have the same risk-free period. While it would be fair to present cases within 2 years per 10000 participants, the estimate of cases per person-years at risk will be biased.

Publication History

Article published online:
30 July 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 DOI: 10.1055/a-2136-6564. (PMID: 37793423)