Cancer patient survival in Estonia 1995-2009: time trends and data quality.

BACKGROUND: Survival from most cancers in Estonia has been consistently below European average. The objective of this study was to examine recent survival trends in Estonia and to quantify the effect on survival estimates of the temporary disruption of the Estonian Cancer Registry (ECR) practices in 2001-2007 when death certificates could not be used for case ascertainment. PATIENTS AND METHODS: ECR data on all adult cases of 16 common cancers diagnosed in Estonia during 1995-2008 and followed up for vital status until 2009 were used to estimate relative survival ratios (RSR). We used cohort analysis for patients diagnosed in 1995-1999 and 2000-2004; and period hybrid approach to obtain the most recent estimates (2005-2009). We compared five-year RSRs calculated from data sets with and without death certificate initiated (DCI) cases. RESULTS: A total of 64328 cancer cases were included in survival analysis. Compared with 1995-1999, five-year age-standardized RSR increased 20 percent units for prostate cancer, reaching 76% in 2005-2009. A rise of 10 percent units or more was also seen for non-Hodgkin lymphoma (five-year RSR 51% in 2005-2009), and cancers of rectum (49%), breast (73%) and ovary (37%). The effect of including/excluding DCI cases from survival analysis was small except for lung and pancreatic cancers. CONCLUSIONS: Relative survival continued to increase in Estonia during the first decade of the 21st century, although for many cancers, a gap between Estonia and more affluent countries still exists. Cancer control efforts should aim at the reduction of risk factors amenable to primary prevention, but also at the improvement of early diagnosis and ensuring timely and optimal care to all cancer patients.

Testicular cancer in Europe and the USA: survival still rising among older patients.

BACKGROUND: Despite high curability, some testicular cancer (TC) patient groups may have increased mortality. We provide a detailed age- and histology-specific comparison of population-based relative survival of TC patients in Europe and the USA. Design Using data from 12 European cancer registries and the USA Surveillance, Epidemiology and End Results 9 database, we report survival trends for patients diagnosed with testicular seminomas and nonseminomas between 1993-1997 and 2003-2007. Additionally, a model-based analysis was used to compare survival trends and relative excess risk (RER) of death between Europe and the USA adjusting for differences in age and histology. RESULTS: In 2003-2007, the 5-year relative survival of patients with testicular seminoma was at least 98% among those aged <50 years, survival of patients with nonseminoma remained 3%-6% units lower. Despite improvements in the relative survival of nonseminoma patients aged ≥ 50 years by 13%-18% units, survival remained markedly lower than the survival of seminoma patients of the same age. Model-based analyses showed increased RERs for nonseminomas, older, and European patients. CONCLUSIONS: There remains little room for survival improvement among testicular seminoma patients, especially for those aged <50 years. Older TC patients remain at increased risk of death, which seems mainly attributable to the lower survival among the nonseminoma patients.

Changes in incidence, survival and mortality of prostate cancer in Europe and the United States in the PSA era: additional diagnoses and avoided deaths.

BACKGROUND: We describe changes in prostate cancer incidence, survival and mortality and the resulting impact in additional diagnoses and avoided deaths in European areas and the United States. METHODS: Using data from 12 European cancer registries and the Surveillance, Epidemiology and End Results program, we describe changes in prostate cancer epidemiology between the beginning of the PSA era (USA: 1985-1989, Europe: 1990-1994) and 2002-2006 among patients aged 40-64, 65-74, and 75+. Additionally, we examine changes in yearly numbers of diagnoses and deaths and variation in male life expectancy. RESULTS: Incidence and survival, particularly among patients aged <75, increased dramatically, yet both remain (with few exceptions in incidence) lower in Europe than in the United States. Mortality reductions, ongoing since the mid/late 1990 s, were more consistent in the United States, had a distressingly small absolute impact among patients aged 40-64 and the largest absolute impact among those aged 75+. Overall ratios of additional diagnoses/avoided deaths varied between 3.6 and 27.6, suggesting large differences in the actual impact of prostate cancer incidence and mortality changes. Ten years of remaining life expectancy was reached between 68 and 76 years. CONCLUSION: Policies reflecting variation in population life expectancy, testing preferences, decision aids and guidelines for surveillance-based management are urgently needed.

Prognostic value of morphology and hormone receptor status in breast cancer - a population-based study.

We analysed the 5-year relative survival among 4473 breast cancer cases diagnosed in 1990-1992 from cancer registries in Estonia, France, Italy, Spain, the Netherlands and the UK. Among eight categories based on ICD-O codes (infiltrating ductal carcinoma, lobular plus mixed carcinoma, comedocarcinoma, 'special types', medullary carcinoma, not otherwise specified (NOS) carcinoma, other carcinoma and cancer without microscopic confirmation), the 5-year relative survival ranged from 66% (95% CI 61-71) for NOS carcinoma to 95% (95% CI 90-100) for special types (tubular, apocrine, cribriform, papillary, mucinous and signet ring cell); 27% (95% CI 18-36) for cases without microscopic confirmation. Differences in 5-year relative survival by tumor morphology and hormone receptor status were modelled using a multiple regression approach based on generalised linear models. Morphology and hormone receptor status were confirmed as significant survival predictors in this population-based study, even after adjusting for age and stage at diagnosis.

The incidence and survival of acute de novo leukaemias in Estonia and in a well-defined region of western Sweden during 1982-1996: a survey of patients aged > or =65 years.

OBJECTIVES: To compare the incidence and survival of acute de novo leukaemias with particular reference to political/socio-economic and environmental factors in two neighbouring countries over the three 5-year periods (1982-1996). PATIENTS: The present report covers only patients diagnosed when aged > or =65 years. SETTING: A well-defined area of Sweden, the so-called Western Swedish Health Care Region and Estonia. Population-wise, the western Swedish Region and Estonia are very similar; area-wise they are also well comparable. RESULTS: The number of acute de novo leukaemias was quite dissimilar in the two countries (Estonia, n = 137, Sweden, n = 354). The age standardized incidence rates regarding the total number of acute de novo leukaemias was 5.31 per 100,000 inhabitants/year for Estonia and 7.99 for Sweden, this difference being statistically significant. However, the difference was merely attributable to incidence rates as regards acute myeloblastic leukaemias (AML); on the contrary, differences as regards acute lymphoblastic leukaemias (ALL) and non-classifiable, undifferentiated or biphenotypic acute leukaemias (uAL) were negligible. The relative survival for the total material of patients was significantly higher for Swedish when compared with Estonian patients (P < 0.001). Thus, the relative survival for the total material of patients aged > or =65 years in Estonia at 1 year was 8.5% and at 3 years 3.5% respectively. The corresponding figures for the Swedish patients were considerably higher, 22.7 and 7.7% respectively. This difference, however, applied only for patients with AML (P < 0.001), whereas the results for patients with ALL and uAL were equally dismal. CONCLUSION: The results clearly reflect how political and socio-economic factors may influence the survival of acute leukemia patients in two neighbouring countries.

European health systems and cancer care.

INTRODUCTION: Data on the survival of all incident cases collected by population-based cancer registries make it possible to evaluate the overall performance of diagnostic and therapeutic actions on cancer in those populations. EUROCARE-3 is the third round of the EUROCARE project, the largest cancer registry population based collaborative study on survival in European cancer patients. The EUROCARE-3 study analysed the survival of cancer patients diagnosed from 1990 to 1994 and followed-up to 1999. Sixty-seven cancer registries of 22 European countries characterised by differing health systems participated in the study. This paper includes essays providing brief overviews of the state and evolution of the health systems of the considered countries and comments on the relation between cancer survival in Europe and some European macro-economic and health system indicators, in the 1990s. OVERVIEW OF THE EUROPEAN HEALTH SYSTEMS: The European health systems underwent a great deal of reorganisation in the last decade; a general tendency being to facilitate expanding involvement of the private sector in health care, a process which occurred mainly in the eastern countries (i.e. the Czech Republic, Estonia, Poland, Slovakia and Slovenia). In contrast, organisational changes in the northern European countries (i.e. Denmark, Iceland, Finland and Sweden) tended to confirm the established public sector systems. Other countries, including the UK and some southern European countries (i.e. England, Scotland, Wales, Malta and Italy) have reduced the public role while the systems remain basically public, at least at present. Our findings clearly suggest that cancer survival (all cancer combined) is related to macro-economic variables such as the gross domestic product (GDP), the total national (public and private) expenditure on health (TNEH) and the total public expenditure on health (TPEH). We found, however, that survival is related to wealth (GDP), but only up to a certain level, after which survival continues to be related to the level of health investment (both TNEH and TPEH). According to the Organisation for Economic Co-operation and Development (OECD), the TNEH increased during the 1990s in all EUROCARE-3 countries, while the ratio of TPEH to TNEH reduced in all countries except Portugal. CONCLUSIONS: Cancer survival depends on the widespread application of effective diagnosis and treatment modalities, but our enquiry suggests that the availability of these depends on macro-economic determinants, including health and public health investment. Analysis of the relationship between health system organisation and cancer outcome is complicated and requires more information than is at present available. To describe cancer and cancer management in Europe, the European Cancer Health Indicator Project (EUROCHIP) has proposed a list of indicators that have to be adopted to evaluate the effects on outcome of proposed health system modifications.

EUROCARE-3: survival of cancer patients diagnosed 1990-94--results and commentary.

EUROCARE-3 analysed the survival of 1815584 adult cancer patients diagnosed from 1990 to 1994 in 22 European countries. The results are reported in tables, one per cancer site, coded according to the International Classification of Diseases (ICD)-9 classification. The main findings of the tables are summarised and commented on in this article. For most solid cancers, wide differences in survival between different European populations were found, as also reported by EUROCARE-1 and EUROCARE-2, despite a remarkable (10%) overall increase in cancer survival from 1985 to 1994. Survival was highest in northern Europe (Sweden, Norway, Finland and Iceland), and fairly good in central-southern Europe (France, Switzerland, Austria and Spain). Survival was particularly low in eastern Europe, low in Denmark and the UK, and fairly low in Portugal and Malta. The mix of tumour stage at diagnosis explains much of the survival differences for cancers of the digestive tract, female reproductive system, breast, thyroid, and also skin melanoma. For tumours of the urinary tract and prostate, the differences were explained mainly by differences in diagnostic criteria and procedures. The case mix by anatomic subsite largely explains differences in survival for head and neck cancers. For oesophagus, pancreas, liver and brain cancer, with poor prognoses, survival differences were limited. Tumours, for which highly effective treatments are available, such as testicular cancer, Hodgkin's lymphoma and some haematological malignancies, had fairly uniform survival across Europe. Survival for all tumours combined (an indicator of the overall cancer care performance of a nation's health system) was better in young than old patients, and better in women than men. The affluence of countries influenced overall cancer survival through the availability of adequate diagnostic and treatment procedures, and screening programmes.

Cancer prevalence in Northern Europe: the EUROPREVAL study.

BACKGROUND: Information on cancer prevalence is of importance for health planning and resource allocation, but is not always available. In order to obtain such data in a comparable way a systematic evaluation of cancer prevalence in Europe was undertaken within the EUROPREVAL project. PATIENTS AND METHODS: Standardised data were collected from 38 population-based registries on almost 3 million cancer patients diagnosed between 1970 and 1992. The prevalence of 11 specific cancer types was estimated at the index date of 31 December 1992. This study deals with the northern countries Denmark, Estonia, Finland, Iceland and Sweden. RESULTS: There were large differences between these countries, Sweden having the highest prevalence rate of 3050 per 100 000 and Estonia the lowest, 1339 per 100 000. This difference is mainly due to a high proportion of cancers with favourable prognosis such as breast cancer, prostate cancer and melanoma, better survival and longer life expectancy in Sweden, whereas Estonia has a higher proportion of stomach and lung cancer with poor prognosis, worse survival and much shorter life expectancy, especially for males. For most tumour types, the Nordic countries did better than Estonia. There are indications that cancer patients in Estonia, as well as in Denmark, have a more advanced stage at diagnosis and that the Estonian health-care system is less efficient. CONCLUSIONS: Despite many similarities and a common historical background, the northern countries in Europe that participated in the EUROPREVAL study display quite different cancer patterns and prevalence. Reasons for these variations are discussed.

Study of completeness of registration at the Estonian cancer registry.

Every cancer registry should be able to quantify the level of completeness of registration. The current study describes a routine quality control procedure in the Estonian Cancer Registry (ECR) for assessing the completeness of registration. The registry's database was compared with the databases of the Tartu University Lung Clinic and the Maarjamõisa Hospital of the Tartu University Clinics, and active retrieval to obtain missing cancer cases diagnosed in 1998 was carried out. The overall completeness of case ascertainment based on this study was 90.8%. As a result of this procedure, 67 cases of malignant neoplasms (1.1% of the total number of incident cancer cases for 1998) and 11 cases of other reportable neoplasms were detected and recorded at the ECR. Cancers of the lung, thyroid gland and prostate were most frequently under-notified. For these sites, the number of cancer cases for 1998 for Estonia as a whole increased 2.6%, 11.8% and 2.2%, respectively. To conclude, the existence of electronic databases is a positive development, but cancer registrars still need to employ labour-intensive methods to validate diagnostic codes and to decide whether to include in the ECR cases found by active retrieval. Based on the findings of our study, which is the first one of its kind in Estonia, the completeness of cancer reporting varied by cancer site, and it appeared to be a substantial concern for several sites.

Variation in survival of children with central nervous system (CNS) malignancies diagnosed in Europe between 1978 and 1992: the EUROCARE study.

EUROCARE is a population-based survival study including data from European Cancer Registries. The present paper analyses survival after a malignant neoplasm of the central nervous system (CNS) in childhood (aged 0--14 years at diagnosis). The database includes 6130 cases from 34 population-based registries in 17 countries: 1558 were primitive neuroectodermal tumours (PNET) and 4087 astrocytoma, ependymoma or other gliomas: these morphologies were grouped in the analyses in order to reduce the diagnostic variability among the registries. 87% of cases were microscopically diagnosed (range among registries 71--100%) and losses to follow-up were limited to 2% (range 0--14%). Actuarial analyses indicate that the European (weighted) average of 5 years cumulative survival for cases diagnosed in 1978--1989 was 53% (95% confidence interval (CI) 49--57) for CNS neoplasms, 44% (95% CI 37--50) for PNET and 60% (95% CI 55--65) for the glioma-related types. Analysis of the sub-set of cases diagnosed in 1985--1989 revealed better results: cumulative survival at 5 years was 61% (95% CI: 55--65) for all CNS neoplasms; 48% (95% CI 41--56) for PNET and 68% (95% CI 62--73) for glioma-related types. Compared with older children, infants showed poorer prognosis: in 1978--1989 the 5-year survival rate was 33% (95% CI 23--45) and in 1985--1989 it was 46% (95% CI 34--59). Variability among countries was very large, with 5-year survival for CNS tumours diagnosed in 1985--1989 ranging from 28% in Estonia (95% CI 17--43) to 73% Sweden (95% CI 59--83) and 75% in Iceland (95% CI 35--95) and 73% in Finland (95% CI 66--79). Time trends were studied in a multivariate analysis observing a reduction in the risk of death in periods of diagnosis 1982--1985 (hazard ratio (HR)=0.85; 95% CI 0.78--0.93) and 1986--1989 (HR=0.70; 95% CI 0.64--0.77) compared with 1978--1981. The analysis were extended to 1990--1992 for the countries whose registries provided data for that period did not indicate any further progress. Results of this study confirm the large variability in European countries and indicate a positive trend in the survival probability for cases diagnosed in the 1980s.

Survival of children with neuroblastoma. time trends and regional differences in Europe, 1978--1992.

Neuroblastoma is one of the most common solid cancers in children. We present the data collected for the EUROCARE II study, describing survival patterns for children diagnosed in Europe 1985--1989 in detail, and exploring time trends from 1978 to 1992. On average, the mean 5-year survival rate was considerably higher in infants (79%) compared with older children (30--33%). The risk of death has dropped by 37% from 1978--1981 to 1990--1992. There is a pronounced difference between countries, with Scotland and England and Wales having two of the lowest survival rates (28% (95% confidence interval (CI) 14--48) and 36% (95% CI 31--41) 5-year survival rates, respectively). The survival rates in France, Germany and Italy (48--66% 5-year survival rate) were among the highest. This pattern corresponds to the incidence rates for these countries. It can be assumed that in neuroblastoma, both incidence and survival are related to the frequency of diagnosing asymptomatic cases with good prognosis among infants. However, one cannot ignore possible intercountry differences in the effectiveness of therapy.

Improved survival for patients with testicular cancer in Europe since 1978. EUROCARE Working Group.

Within the framework of EUROCARE, a population-based study on survival and care of cancer patients in Europe, we analysed survival of 7426 men with testicular cancer diagnosed between 1985 and 1989 in 17 countries. For comparison between the countries, survival rates were age-standardised to the age structure of the entire study population. Among the participating countries of Northern, Western, Central and Southern Europe and the U.K., the age-standardised 5-year relative survival rate varied from 89% (Finland) to 93% (Spain, Germany). In Eastern Europe, the rate ranged from 48% (Estonia) to 84% (Slovenia). Rates in Poland, Slovakia and Estonia were significantly lower than the summary rate for Europe (P < 0.05). Relative survival generally decreased with the age of patients at diagnosis. Based on the weighted analysis of pooled European data, the 5-year relative survival rate was 91% for patients aged 15-44 years; 85% for patients aged 55-64 years; and 59% for patients aged 75 years and over. The time trend in survival by 3-year periods between 1978 and 1989 was studied on the basis of 12,084 cases provided by 12 countries. From 1978-1980 to 1987-1989, the 5-year relative survival rate for Europe increased from 79 to 93% (P < 0.05). The inequalities in survival between the more developed European countries were more notable in the 1970s than in the 1980s, suggesting that the treatment for testicular cancer became standardised in the latter period. Poorer survival in Eastern Europe and particularly in Estonia, could be related to later introduction of the effective cytotoxic treatments, but also to longer diagnostic delay and limited availability of modern staging procedures.

Cancer survival in Estonian migrants to Sweden.

OBJECTIVE: To quantify the eventual extra loss of life incurred to cancer patients in Estonia compared with those in Sweden that was possibly attributable to differences in society. DESIGN: Population based survival of cancer patients in Estonia was compared with that of Estonian immigrants to Sweden and that of all cancer patients in Sweden. The cancer sites studied were female breast and ovary, male lung and prostate, and male and female stomach and colon. SETTING: Data on incident cases of cancer were obtained from the population based Swedish and Estonian cancer registries. PARTICIPANTS: Data from Estonian patients in Sweden, Estonian patients in Estonia, and patients from the total Swedish population were included in the study. MAIN RESULTS: Differences in survival among the three populations, controlling for follow-up time and age at diagnosis, were observed in breast, colon, lung, ovarian, and prostate cancers. The survival rates of Estonians living in Sweden and the total population of Sweden were better than that of the Estonians living in Estonia. For cancers of the breast and prostate, the excess mortality in the older age group (75 and above) was much greater in Estonia than in the other populations. CONCLUSIONS: Most differences in cancer survival between Estonian and Swedish populations studied could be attributed to a longer delay in diagnosis, and also to inferior treatment (including access to treatment) in Estonia compared with Sweden. Estonia's lag in socioeconomic development, particularly in its public health organisation and funding, is probably the main source of the differences observed.

Bladder cancer in Estonia, 1968-1992: incidence, mortality, prevalence and survival.

This paper summarizes what is known about the occurrence and survival of bladder cancer in Estonia from 1968 to 1992. In 1988-92 the age standardized (world standard) incidence rate of bladder cancer was 11.1 per 100,000 person-years in males and 2.0 in females, and the age standardized mortality rate was 8.2 and 2.7, respectively; by July 1, 1990 the age standardized prevalence rate was 41.5 and 14.7, respectively. Between 1968-72 and 1988-92, incidence increased by 1.26 times (95% confidence interval 1.09 to 1.46) among males; incidence rates for females did not show a consistent trend. The time trends in mortality generally paralleled the trends in incidence. Higher rates of bladder cancer were found among males in five large towns. For patients diagnosed in 1983-87, the five-year relative survival was 32.4% (95% confidence interval 27.0 to 37.8) for males and 32.5% (23.8 to 41.2) for females; throughout the 20 years there was no improvement in survival. As the survival rates are less favorable than those in the Nordic countries, further hospital-based studies are needed to investigate the relation between survival and clinical characteristics.

Lung cancer in Estonia in 1968-87: time trends and public health implications.

Changes in lung cancer incidence and mortality in Estonia were studied for 20 years (1968-87). A steady upward trend was observed for men and women. The 1983-87/1968-72 age-standardized incidence rate ratio was 1.22 (95% confidence interval (CI) 1.15-1.29) in men and 1.34 (95% CI 1.16-1.54) in women. The corresponding mortality rate ratio was 1.26 (95% CI 1.18-1.34) in men and 1.35 (95% CI 1.16-1.57) in women. The age-specific incidence and mortality rates increased clearly towards the younger birth cohorts. For men and women, the increase was most evident for the age group 45-64 years. In women there was a more rapid increase in incidence and mortality than in men. It may be a result of a substantial increase of tobacco smoking, particularly among women, after the World War II. The high and still rising occurrence of lung cancer is closely related to the high prevalence of smoking; in addition, high tar yields in domestic cigarettes could have been responsible for an elevated lung cancer risk during the past decades. There is not tobacco control programme in Estonia, and existing legislation and regulations do not defend the non-smoking population.

Cancer incidence in Estonian migrants to Sweden.

Cancer incidence in Estonians who took refuge in Sweden in 1944-1945 has been compared with that in the total Swedish population and that among Estonians in Estonia in 1974-1985 using data from the Swedish and the Estonian countrywide population-based cancer registries. The vast majority of the Estonian immigrants studied had been living in Sweden for 30 years when the follow-up with respect to cancer incidence started in this investigation. In spite of the long residence in Sweden, differences in cancer incidence could be observed between these immigrants and the total Swedish population. The age-standardized incidence of stomach cancer was higher in the Estonian migrants than in the total Swedish population (SIR = 1.6 and 2.1 for males and females, respectively). Breast cancer incidence was lower in the migrant women (SIR = 0.75) and lung cancer incidence higher in migrant men (SIR = 1.5). An increased incidence of colorectal cancer was also found for both sexes in the migrant population (SIR = 1.4 for both males and females). A comparison between Estonians in Estonia and the total Swedish population revealed that the cancer incidence for the Estonians was lower than expected at age 70 and over. Male lung cancer and stomach cancer showed a higher incidence in the Estonian population than in the Swedish and in the migrant populations. The migrant population showed an intermediate incidence relative to Estonians in Estonia and the entire Swedish population. The colon-cancer risk in Estonian migrants to Sweden was higher than the risk for Estonians in Estonia and for the Swedish population. This contrasts with most findings in the present and other studies on intermediate risks of migrants compared to the risks in the country of origin and in the new country of residence.

Cervical cancer incidence and mortality trends in Finland and Estonia: a screened vs. an unscreened population.

Long term trends in the incidence of and mortality from invasive cervical cancer have been studied in Finland (1953-1987) and Estonia (1968-1987). The analyses are based on the data from the Finnish and Estonian Cancer Registries. An organised nationwide screening programme for cervical cancer was started in Finland in the early 1960s. In Estonia, no cytological screening programme has been introduced, and cervical malignancies are diagnosed in routine gynaecological practice. During 1968-1987, both the incidence of and mortality from cervical cancer were considerably higher in Estonia than in Finland. A decrease has taken place in the cervical cancer incidence and mortality in both countries since the mid-1960s, but whereas in Finland the decrease has been marked, in Estonia it has been less pronounced and levelled off in the 1980s. In 1987, the age-standardised (world population) incidence rate per 100,000 women was 14.0 in Estonia and 3.8 in Finland, and the age-standardised mortality rate was 6.0 and 1.6 per 100,000, respectively. The difference in the incidence of the disease in the two neighbouring countries can be partially attributed to socioeconomic factors. The main reason for the different slopes of the trend curves for cervical cancer is probably the difference in public health policies: an effective mass screening programme is being conducted in Finland but not in Estonia.

Cancer survival in Estonia from 1978 to 1987.

On the basis of the Estonian Cancer Registry's data bank, survival was examined for 36,020 incident cancer cases diagnosed from 1978 to 1987 in men and women residing Estonia. The number of cases, the proportion of cases with microscopic verification, the observed and relative 5-year survival rates, and the median survival time were determined for 25 most common cancer sites and all sites combined. The highest relative survival rates were documented for cancers of the lip, corpus uteri, and skin (melanoma, women). The lowest rates were found for acute myeloid leukemia (women), and cancers of the liver, pancreas, and esophagus (men). For most cancer sites, the survival rates of women exceeded those of men. The comparison of nationwide survival rates by selected sites in Estonia with those in Finland revealed that Estonian rates were lower. Existing information shows that the Estonian Cancer Registry has relatively good data resources for promoting more sophisticated survival studies.

On the background of differences in survival of female breast cancer patients in the German Democratic Republic and the Estonian SSR.

The aim of this study was to describe the age-specific survival patterns and to analyse the differences between the survival rates of female breast cancer patients in the German Democratic Republic in 1976-1977 and the Estonian SSR in 1968-1981. The estimated 5-year relative survival rate (RSR) was 64.1% in the GDR and 55.9% in Estonia. Patients aged 55 years or older at diagnosis had higher survival in the GDR (5-year RSR 62.6%) than in Estonia (49.5%). That result was clearly connected with higher proportion of advanced tumors among older patients in Estonia. For patients younger than 55 years the difference of the 5-year RSR between the both countries was not statistically significant (GDR 65.3%, Estonia 63.4%). The standardization of overall 5-year RSR by stage and age, but also only by stage of the disease produced virtually equal results for the GDR and Estonia. It means that the main source of the differences in overall breast cancer survival rates between the GDR and Estonia are the discrepancies in stage distribution, particularly in older age groups.