Route to diagnosis of colorectal cancer and association with survival within the context of a bowel screening programme

Objectives: Bowel cancer screening has been introduced to improve colorectal cancer outcomes; how-ever, a significant proportion of cases continue to present with TNM Stage III-IV disease and/or emer-gently. This study analyses the prior interaction with screening of patients diagnosed with colorectal cancer and factors associated with non-screening diagnosis. Study design: This was a retrospective observational study. Methods: All patients diagnosed with colorectal cancer in the West of Scotland from 2011 to 2014 were identified. Through data linkage to the Scottish Bowel Cancer Screening Programme, we analysed patient interaction with screening within 2 years before cancer diagnosis. Results: In total, 6549 patients were diagnosed with colorectal cancer, 1217 (19%) via screening. Screening participation was associated with earlier TNM stage, reduced emergency presentations and improved 3-year survival (all P < 0.001). Failure to diagnose through screening was predominantly due to non-invitation (37%), non-return of screening test (29%) or negative test (13%). Three hundred fifty-one patients were below screening age, 79% of whom were aged 40-49 years and 2035 patients were above screening age. Factors associated with non-return of screening test included age, sex, SIMD (all P < 0.001) and raised Charlson score (P = 0.030). Factors associated with negative screening result included sex, anaemia, differentiation, right-sided tumours and venous invasion (P < 0.001). Conclusion: Within Scotland, <20% of colorectal cancer is diagnosed through screening despite the ex-istence of a population screening programme. Measures must be taken to improve screening partici-pation including encouragement of those of routine screening age and those age >= 75 years in good health to participate in screening with consideration given to extending screening to under 50s. A sig-nificant false-negative rate of testing was observed in the present study and this requires further investigation within a population undergoing screening through faecal immunochemical testing. (c) 2022 The Author(s). Published by Elsevier Ltd on behalf of The Royal Society for Public Health. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).