Cancer in Estonia: Rates and Validity

Estonia is a small country in the north-eastern Europe, with its history dating back more than 5 000 years. This thesis gives an overview of the history, development and current cancer registration process in the Estonian Cancer Registry. Cancer registration in Estonia dates back to 1953, when it mostly adhered to cancer registration principles of the Soviet Union which the country was part of. Since 1970s the cancer registration principles diverged from the Soviet ones. The current procedure of cancer registration in Estonia (which restored its independence in 1991) operates on principles that are quite similar to those used in the Western countries. Over the recent years, the Estonian Cancer Registry has established itself as a high standard cancer registry with a rather extensive use of data. Up to now, no special studies concerning the quality of cancer registration have been carried out in Estonia. The three studies performed in the framework of this thesis looked at different quality characteristics of Estonian Cancer Registry data, such as validity and completeness of cancer registrations items, as well as completeness of coverage. The data quality in the Estonian Cancer Registry was found to be good in general. The Estonian Cancer Registry data were used to analyse trends and variations in cancer incidence and mortality for all cancers as well as by most frequent sites. The analysis showed that total cancer incidence and mortality in Estonia increased during 1985-1997. From specific cancer sites, incidence and mortality of all urologic cancers increased. At the same time, decline in lung cancer incidence in men and stomach cancer incidence in both sexes were observed. Cancer incidence and mortality in Estonia was compared with that for the Nordic and the Baltic countries. The comparison revealed that Estonia is positioned rather high for the incidence of all smoking related cancers as well as stomach, kidney and prostate cancers. Cancer incidence between ethnic Estonians and Russians was compared to illustrate the use of the ECR data. This study showed that ethnic differences exist. For example, there is a higher incidence of cancers of stomach and pancreas in Russians compared to Estonians in Estonia for both sexes, and lung cancer for men. Recommendations for improvements in cancer registration system in Estonia as well as for further studies on the quality of cancer registrations and for the Estonian health care system were given.