Effectiveness of population-based colorectal cancer screening programme in down-staging.

ABSTRACT

BACKGROUND: This is the first evaluation study to assess the demographic characteristics of the colorectal cancer (CRC) cases detected in the prevalent round of the population-based Colorectal Cancer Screening Programme (CRCSP) in Hong Kong and to explore the effectiveness of the programme on the stage distribution of CRC. METHODS: This study covered the period between 28 September 2016 and 31 December 2018. Information on CRC diagnosis, age and stage at diagnosis were retrieved and reviewed by the Hong Kong Cancer Registry (HKCaR). The CRC detection rate among CRCSP-screened participants and incidence rate among the Hong Kong general population were calculated respectively. The odds ratio (OR) was calculated to measure the strength of association and quantify the effect of CRCSP on stage shift between CRCSP-detected CRC cases and an age-matched cohort of CRC cases diagnosed outside the programme. RESULTS: The CRC detection rate among participants of the CRCSP during the study period was 736.0/100,000, whereas the overall CRC incidence rate among general population of similar age groups was 393.7/100,000. For all ages and both sexes, the OR of stage I CRCSP-detected CRC compared to the CRC from the age-matched cohort was 3.91 (95%CI=3.41-4.48) and the OR dropped to 0.54 (95%CI=0.41-0.70) at stage IV. Meanwhile, the overall OR of CRCSP-detected CRC compared to CRC from the age-matched cohort dropped from 2.24 (95%CI=1.97-2.56) to 1.62 (95%CI=1.40-1.87) with increasing age. CONCLUSION: The present study has demonstrated the initial impact of the CRCSP on shifting the stage at diagnosis towards earlier stage. The benefit of stage-shift was similar for all ages from 60 to 77 in both sexes and seems to increase with younger age. Given the stage-dependent survival outcomes, this stage-shift could lead to a reduction in CRC-associated mortality in Hong Kong in future.