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 25-74years 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 6-8years, 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 45-74years. Conversely, incidence rates of micro-invasive (stage IA) ICCs increased, though not significantly, among women aged 25-44years (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.

Keywords: Cervical cancer; Incidence rate ratio; Organized screening; Pap-smear.