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.
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.
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.
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.
- • A case-control study was conducted to examine cervical cancer risk factors.
- • Risk was 2.5 times higher in women with no Pap-smears vs. at least one in 7 years.
- • Risk increase was also associated with lower education and being divorced/widowed.
- • Large regional risk differences were seen in women with and without a Pap-smear.
- • The results suggested problems with the quality of Pap-smear and/or clinical follow-up.
Population-based cervical cancer (CC) screening programmes with Pap-smear as the main primary screening test have contributed to a rapid decline in CC incidence and mortality in many countries worldwide. However, this has not been the case in several Baltic and Eastern-European countries , mainly due to low participation rates and absence of quality assurance in organised screening programme, lack of centralised screening registration and no reliable screening indicators .
Although the national CC screening programme in Estonia started in 2006, CC incidence has remained high and well above the European Union average (27.4/100,000 vs. 12.8/100,000 in 2020, respectively) . Furthermore, the mortality rates in Estonia are even four times higher than in neighbouring Finland and more than twice as high as in Sweden . An age-period-cohort analysis in Estonia showed an increasing risk in successive birth-cohorts born after 1940s with no period effects to suggest any impact of opportunistic or organised screening . The participation of targeted annual birth cohorts in organised CC screening has consistently remained below 50% , compared to the nearly 70% rate in Finland . At the same time there is evidence of high uptake of opportunistic screening as the total 5-year Pap-smear coverage in the screening target age group in Estonia (age 30–55) is as high as 81%, which is quite similar to the coverage of screening age group (age 30–64) in Sweden (86%) and Finland (86%) .
Previously, there had been no studies to examine the association between individual Pap-smear history and CC risk in Estonia. Therefore, it was unknown whether CC cases occur among the minority of women with no previous Pap-smears or those with a recent Pap-smear.
The aim of the study was to examine the reasons for high CC incidence in Estonia, by comparing the history of having no Pap-smears during the past seven years between CC cases and healthy controls. As a secondary objective, we estimated the effect of sociodemographic factors on CC risk.