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; however, a significant proportion of cases continue to present with TNM Stage III-IV disease and/or emergently. 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 existence of a population screening programme. Measures must be taken to improve screening participation 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 significant 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.