Pap-smear and cervical cancer in Estonia: a population-based case-control study

Abstract

Abstract Backround Studies have shown the ineffectiveness of Estonian cervical cancer (CC) screening programme. To examine the reasons for high CC incidence in Estonia, a study was conducted, linking individual Pap-smear history to CC incidence. Methods In this population-based case-control study, cases were women aged ≥25 years with an in situ/invasive CC diagnosed in Estonia in 2011-2017, derived from cancer registry. Three controls per case were randomly selected from population registry using a density sampling scheme. Exposure was defined as no Pap-smears during seven years prior to diagnosis or index date compared to at least one smear. Multivariate logistic regression was used to calculate odds ratios (OR) with 95% confidence intervals (CI). Age, place of residence, citizenship, education, marital status and interruption in health insurance were also analysed. The analysis was done separately in screening age group (35-60 years). Results Among 1439 cases and 4317 controls, the proportion of women with no Pap-smears was 53% and 35%, respectively. In multivariate analysis, women with no Pap-smears were at a higher risk for CC (OR = 2.42; 95% CI: 1.97-2.97). In screening age group, the impact of no Pap-smears was stronger (OR = 2.62; 95% CI: 2.12-3.24). CC risk decreased with age, was two to three times higher in other regions compared to Northern Estonia; was higher for lower-educated women; and for divorced/widowed women compared to married women. Interruption in health insurance caused a 25% increase in risk. However in screening age group, women with no Pap-smears and an interruption in health insurance experienced a four-fold increase in CC risk. Conclusions The study confirmed the importance of screening in preventing CC, also revealing the independent effect of several social factors on CC risk. To reduce CC incidence in Estonia, immediate efforts are necessary to increase the effectiveness of screening, particularly among high-risk and hard-to-reach women. Key messages This case-control study of cervical cancer in Estonia identified high-risk groups: women with no Pap-smears, interruptions in health insurance, low education, and living outside the capital city area. Reduction in cervical cancer incidence in Estonia can be achieved through more effective screening and communication, tailored to the needs of different population groups, mainly high-risk women.