A delay in the diagnosis of colorectal cancer screened by fecal immunochemical tests during the COVID-19 pandemic: a longitudinal cohort study

Purpose: There is concern that the COVID-19 pandemic may cause people to refrain from undergoing examination resulting in delayed detection of colorectal cancer (CRC). The purpose of this study was to investigate whether there was a delay in CRC detection due to withholding of screening. Methods: The colonoscopy screening rate and the CRC detection rate were calculated for patients who underwent fecal immunochemical tests (FITs) from 2018 to 2021 in the longitudinal cohort. The stages of CRC cases detected as a result of positive FIT in each year were compared. Results: A total of 39,521 patients were initially screened by FIT over a 4-year period. The FIT-positive rate was 4.7% (441 /9,349) in 2018, 4.6% (420 /9,156) in 2019, 4.9% (453 /9,255) in 2020, and 4.3% (504 /11,760) in 2021. The colonoscopy screening rate for positive FIT results was lower in 2020 than in 2019 (25.8% vs. 38.1%, P < 0.001), and higher in 2021 than in 2020 (56.7% vs. 25.8%, P < 0.001). The CRC detection rate among colonoscopy recipients was higher in 2021 than in 2020 (13% vs. 4%, P = 0.014). Stage 1 or higher CRC accounted for 25.0% (1/4) in 2020, and 78% (18/23) in 2021. Among the CRC cases detected each year, 1 (14%), 1 (25%), and 10 (43%) did not undergo colonoscopy despite positive FIT results in the previous year. Conclusions: The COVID-19 pandemic has reduced the detection of CRC by screening colonoscopy following FIT and might have led to a delay in the detection of CRC.