# Effect of colonoscopy screening on the risk of colorectal cancer in China: a follow-up study

## TL;DR

This study in China found that colonoscopy screening reduces colorectal cancer risk but is limited by low participation and poor treatment adherence.

## Contribution

The study evaluates colonoscopy screening effectiveness in China, highlighting real-world limitations like low adherence and participation.

## Key findings

- Colonoscopy screening reduced CRC incidence by 63% compared to non-screened groups.
- Only 25.93% of CAN patients received treatment despite high follow-up rates.
- CRC mortality did not significantly differ between screened and non-screened groups.

## Abstract

Colorectal cancer (CRC) is one of the most common cancers worldwide. Colonoscopy is the gold standard for CRC screening, but its effectiveness in population-based programs requires further evaluation.

We conducted a follow-up study in Xuzhou, China. Participants were recruited from 2014 to 2021, with follow-up continuing until December 2023. The study comprised two components: 1) an active follow-up to assess treatment outcomes for patients with colorectal advanced neoplasia (CAN) detected during screening; 2) a passive follow-up to compare CRC incidence and mortality between participants who underwent colonoscopy and those who refused it.

The active follow-up included 196 participants, while 15,440 were included the passive follow-up (4,029 in the colonoscopy group and 11,411 in the non-colonoscopy group). 96.43% (189/196) CAN patients were actively followed. However, only 25.93% (49/189) received treatment. The CRC incidence density was 35.77 per 100,000 person-years in the colonoscopy group, which was significantly lower than the 95.50 per 100,000 in the non-colonoscopy group (IRR = 0.37, P = 0.011). 83.33% (5/6) of the CRC cases in the colonoscopy group were from the subgroup of CAN patients who did not receive treatment. There was no significant difference in CRC mortality between the two groups.

Colonoscopy screening is effective in reducing the risk of CRC. However, its real-world effectiveness has been compromised by the low participation rate and the poor treatment adherence among screen-positive patients. The impact of colonoscopy screening on reducing CRC mortality remains undetermined.