Trends in cervical cancer incidence and survival in Estonia from 1995 to 2014.

BACKGROUND

Cervical cancer (CC) incidence in Estonia is the third highest in Europe, even though an organised nation-wide screening program has been in place since 2006. The aim of the study was to analyse the incidence and survival of CC in Estonia, focusing on age, morphology and stage at diagnosis.

METHODS

Data from Estonian Cancer Registry were used to analyse age-standardized (world) and age-specific incidence for 1968-2014 rates. Joinpoint regression was used to estimate the annual percentage change (APC) for incidence trends. Age-period-cohort model was used to summarise time trends in terms of cohort and period effects. Relative survival ratios (RSR) were calculated for cases diagnosed in 1995-2014. Union for International Cancer Control version 7 of the TNM classification for malignant tumours was used to categorise stage.

RESULTS

The age-standardized incidence of CC increased since 1980s at a rate of 0.8% per year. A significant increase was seen for all age groups except for 70+. The incidence of squamous cell carcinoma mimicked the overall trend, while adenocarcinoma showed increase since mid-1990s (APC 6.7). Age-period-cohort modelling showed strong cohort effects with the lowest risk for birth-cohorts born around 1940 and significantly increasing risks for successive cohorts born thereafter. No period effects were seen. The proportion of stage IV cases increased from 13% in 2005-2009 to 18% in 2010-2014. A significant increase was seen in the overall 5-year RSR from 1995 to 1999 to 2010-2014 (58% vs 66%). In 2010-2014, the 5-year RSRs ranged from 89% in women aged 15-39 to 41% in age group 70+. For stages I to IV, the respective RSRs were 98, 74, 57 and 22%.

CONCLUSIONS

The inadequate uptake and insufficient quality of the Pap-smear based screening program has not brought along a decline in the incidence of CC in Estonia. Stage distribution has shifted towards later stages. New approaches are needed to prevent CC in Estonia.