Changes in cervical cancer incidence following the introduction of organized screening in Italy.

Abstract Objective To quantify the impact of organized cervical screening programs (OCSPs) on the incidence of invasive cervical cancer (ICC), comparing rates before and after activation of OCSPs. Methods This population-based investigation, using individual data from cancer registries and OCSPs, included 3557 women diagnosed with ICC at age 25–74 years in 1995–2008. The year of full-activation of each OCSP was defined as the year when at least 40% of target women had been invited. Incidence rate ratios (IRRs) with 95% confidence intervals (95% CIs) were calculated as the ratios between age-standardized incidence rates observed in periods after full-activation of OCSPs vs those observed in the preceding quinquennium. Results ICC incidence rates diminished with time since OCSPs full-activation: after 6–8 years, the IRR was 0.75 (95% CI: 0.67–0.85). The reduction was higher for stages IB–IV (IRR = 0.68, 95% CI: 0.58–0.80), squamous cell ICCs (IRR = 0.74, 95% CI: 0.64–0.84), and particularly evident among women aged 45–74 years. Conversely, incidence rates of micro-invasive (stage IA) ICCs increased, though not significantly, among women aged 25–44 years (IRR = 1.34, 95% CI: 0.91–1.96). Following full-activation of OCSPs, micro-invasive ICCs were mainly and increasingly diagnosed within OCSPs (up to 72%). Conclusion(s) Within few years from activation, organized screening positively impacted the already low ICC incidence in Italy and favored down-staging.