A comprehensive assessment of the impact of a colorectal cancer screening program in a northern Italian area

Abstract

Background: The impact of a faecal immunochemical test-based colorectal cancer (CRC) screening program in terms of patient prognosis could be affected by lead-time bias, which artificially increases the survival of screen-detected patients due to the early diagnosis.

Aims: To provide a description of the impact of the CRC screening program in the Trentino Region (Italy), including the Cure Fraction (CF), a prognostic indicator not affected by lead-time bias.

Methods: The program started in 2008, inviting the resident population aged 50-69 years. In this retrospective cohort study, 1,697 CRC diagnosed between 2003 and 2014 in patients aged 50-69 years were classified as pre-screening (PS), screen-detected (SD), interval cancers (IC) and not-screen-detected (NSD). We compared groups by stage at diagnosis and CF. Trends in CRC mortality were reported.

Results: The proportion of stage I among SD cases was 51%, higher than PS (19%; OR 4.66, 95%CI 3.50-6.20), NSD (20.6%; OR 3.96, 95%CI 2.95-5.32) and IC (33.3%; OR 2.11, 95%CI 1.10-4.04). The CF of PS, NSD and SD cases was respectively 57% (95%CI 54-60%), 60% (95%CI 58-63%) and 93% (95%CI 89-96%). CRC mortality dropped from 40.7 to 25.6\100,000.

Conclusion: The program significantly improved the prognosis of patients, decreasing CRC mortality and incidence of advanced CRCs.

Keywords: Cancer epidemiology; Cancer prevention; Colorectal cancer screening; Hemoccult.