摘要:Effective quality assurance is essential in any screening programme. This article provides a unique insight into key quality indicators of five rounds of the first population-based colorectal cancer screening programme implemented in Spain (2000–2012), providing the results according to the type of screening (prevalent or first screen and incident or subsequent screen) and test (guaiac or immunochemical). The total crude participation rate increased from 17.2% (11,011) in the first round to 35.9% (22,988) in the last one. Rescreening rate was very high (88.6% in the fifth round). Positivity rate was superior with the faecal immunochemical test (6.2%) than with the guaiac-based test (0.7%) (p