Introduction

Colonoscopy and polypectomy reduce the incidence of colorectal carcinoma (CRC), however it does not entirely prevent the emergence of tumours. Post-colonoscopy CRC (PCCRC) is defined when a tumour is detected in a short follow-up period after an index colonoscopy, where no malignancies were found. This period is hard to define however, as the World Endoscopy Organisation (WEO) does not have a unified decision on this subject, the most widespread period is a five-year long.

Aims & Methods

Our aims were to define the incidence of PCCRC at the University of Szeged, and to identify factors that could influence its detection. Patients diagnosed with CRC between 01.01.2020. and 31.12.2023 were involved. For PCCRC, we used 5-, 3- and 1-year cut-off point. We also investigated the indicators of quality colonoscopy as a predictor and assessed the adherence to guidelines regarding the management of the involved patients.

Results

Overall, 3900 CRCs were diagnosed during the study period, the ratio of PCCRC was 3.82% (N=149), 3.08 (N=120), and 1.13% (N=44) with 5-year, 3-year, and 1-year cut-off, respectively. Regarding PCCRC etiology, 64.5% (N=111) of the cases were missed lesions, 9.4% (N=14) were due to incomplete polypectomy and 16.11% (N=24) were de novo lesions. 40% (N=60) was localized on the right side of the colon, 33% (N=49) was on the left, 30% (N=45) in the rectum. Duplex tumours were detected in 5 cases. From the indicators of quality colonoscopy, coecal intubation was documented in 79% (N=117) of the cases, and adequate bowel preparation was achieved in 76% (N=113), both of which does not reach the required minimum value set by the guidelines. There was no substantial difference between the ratios of CRCs and missed lesion PCCRCs regarding lymph node involvement (grade III) and distant metastases (grade IV) (27.24% vs 23.42% and 26.30% vs 22.52%). Adherence to the adequate follow-up strategy stated by the guidelines currently in effect regarding the results of the index colonoscopy was 60.40% (N=90), negligence of the patients was responsible in 32.20% (N=19) in the non-adherent cases.

Conclusion

The incidence of PCCRC in our institution correlates with the data available worldwide. 75% of PCCRCs are missed lesions, and every third examination was carried out with insufficient bowel preparation and/or without coecal intubation and with inadequate follow-up strategy. The incidence of PCCRC can be lowered with quality colonoscopy and strict adherence to guidelines.