Effect of Pap-smear and sociodemographic factors on cervical cancer risk in Estonia: A population-based case-control study

Background: Like many Eastern-European countries, Estonia struggles with ineffective cervical cancer (CC) screening. Despite a long-term organised screening programme and high overall Pap-smear coverage, CC incidence and mortality remain very high. The aim of the study was to examine the reasons for high CC incidence in Estonia by analysing the effect of Pap-smears and sociodemographic factors on CC risk.

Methods: In this population-based case-control study, women aged ≥ 25 years with an in situ/invasive CC diagnosed in Estonia in 2011-2017 were defined as cases. Using a density sampling scheme, controls were randomly selected from general population. To estimate CC risk associated with having no Pap-smears during seven years before diagnosis (cases) or index date (controls), place of residence, interruption in health insurance, and several sociodemographic factors, multivariate logistic regression was used to calculate odds ratios (OR) with 95% confidence intervals (CI). Individual-level data from three population-based registries were used.

Results: Among 1439 cases and 4317 controls, proportion of women with no Pap-smears was 53% and 35%, respectively. Women with no Pap-smears were at higher risk for CC (OR=2.35; 95% CI: 1.85-2.98). CC risk was increased among women who were younger, living in more remote regions, lower-educated, or divorced/widowed. Interruption in health insurance was associated with a 23% risk increase. Regional differences in CC risk were observed among screened women.

Conclusion: To reduce the risk of CC in Estonia, efforts are necessary to increase screening coverage among high-risk women and ensure the quality of CC screening programme. Screening approaches and communication should be tailored to the needs of different population groups. Further studies are warranted to identify the reasons for regional differences in CC risk.