Interpreting Survival Differences and Trends

Cancer Patient Survival in the Elderly in Italy

Aims and background

Italy, like most western populations, is sharply aging and changing its age structure with a striking increase in the oldest segment of the elderly. Since age is related to an exponential growth of cancer incidence rates and to a worsening of prognosis, the progressive aging of the population will constitute, in the future, an issue increasingly more important for public health. The present study is the first effort to present and analyze survival rates in Italian elderly cancer patients in order to provide a starting point for the development of better clinical strategies addressed to the aged.

Materials and methods

The presented data come from a large data set consisting of survival data relating to 25,798 men and 20,479 women, aged 65–84 years at diagnosis, collected by Italian cancer registries participating in the ITACARE project. Relative survival rates of patients have been calculated by sex, quinquennial age classes and the considered entire age class for overall malignant neoplasms and the 10 most frequent cancer sites in the elderly.

Results

When all Italian data for all cancers in the 65–84 year age group were pooled, survival rates at 5 years from the diagnosis was 27% and 39% in men and women, respectively. As regards specific sites, survival rates below 50% were observed for lung, stomach and ovary cancer at 1 year from diagnosis. At 5 years from diagnosis, the rates were less than 50% for colon, prostate, cervix, multiple myeloma, non-Hodgkin's lymphoma and melanoma (only in men). The best survival at 5 years from diagnosis (above 50%) was in women for melanoma and corpus uteri and breast cancer. For all cancers, the prognosis for women was better in each considered age group even though a dramatic decrease in survival with age was observed in both sexes. In general, a similar decline in survival with increasing age characterized all considered specific sites. However, at closer observation, the patterns of a decrease revealed some differences. The ratio between the survival rates of 55–64 vs 65–84 year age class indicated that the sites with the greatest advantage of survival for younger patients (ratio >1.5) were ovary, lung and melanoma (only in men), whereas the least advantage was observed for colon, corpus uteri, breast and prostate. By calendar periods, excluding non-Hodgkin's lymphoma for women, an increase in survival was observed for all considered sites, improving an encouraging successful trend in diagnostic and therapeutic progresses.

Studying Survival of Cancer Patients in Different Populations: Its Potential and Role

Rationale

Survival figures from a population-based study incorporate the overall practice in diagnosis, cure and clinical follow-up for a specific disease within a given health care system. Being the outcome of a number of individual, social and economical aspects, population-based survival may be thought as index for measuring the level of a country's development.

Data

The EUROCARE project, a European Cancer Registries (CR) concerted action, provided reliable information on survival for more than 800,000 cancer patients from 11 European countries. A great deal of epidemiologic information has derived from EUROCARE. Women had a longer survival than men for all studied tumour sites, except for the colon. European survival variability was fairly high for several cancers, but it was lower for cancers with a relatively good prognosis and those sensitive to treatment. The ranking of populations of cancer survival tended to be fairly stable for many cancers: CR of Switzerland and Finland ranked high and Polish CR low. Denmark, Italian and France CR did not substantially differ from the European survival average. For most cancers, prognosis improved during the studied period (years of diagnosis: 1978–1985). Survival figures for colon (r = 0.74, males; r = 0.73, women) and female breast cancer (r = 0.57) well correlated with the national health expenditure of different participating countries. The ITACARE study, a new Italian Cancer Registries collaborative project involving more than 100,000 cancer patients, was set up to study survival differences within the country. Survival of cancer patients was not homogeneous in 7 studied Italian regions (the estimated 5-year relative survival for all malignant neoplasms combined ranked from 37.8% in CR of Sicily to 42.1% in those of Emilia-Romagna). The lowest levels of regional health expenditures were accompanied by the lowest levels of prognosis for overall cancers. However, a relatively low correlation among patient cancer survival and the regional health expenditure (r = 0.21) was found, suggesting that other factors such as different efficiency in managing cancer may play a role in explaining the intracountry differences.

Conclusions

Population-based survival figures may be used to study epidemiologic aspects, comparing different health systems, and may be interpreted as indexes for discussing inequalities in health in different populations.

Survival in Adult Italian Cancer Patients, 1978–1989

Aims

To present a systematic analysis of population-based cancer patient survival in Italy.

Methods

Population-based survival data have been made available from 10 Italian cancer registries within the ITACARE project. Data, collected and validated using a common protocol, included over 100,000 patients with cancer diagnosed between 1978 and 1989. Multivariate weighted analysis was used to provide relative survival estimates attributable to Italy at national level.

Results

Results are presented, according to a systematic frame, as the main object of the ITACARE study, involving crude and relative survival figures for adult Italian cancer patients, by age, sex, period of diagnosis and registry area. An estimate with reference to Italy as a whole is also presented by cancer site and for all malignant neoplasms combined. Age-standardized relative survival figures are presented to allow comparisons between Italian registries and also to give a basis for international comparisons with countries involved in the EUROCARE study.

Conclusions

For the fist time, population-based survival of cancer patients is made available in Italy on a large scale analysis of data from all the Italian cancer registries in a combined action. Estimates of cancer patient survival at a national level in Italy allow proper international comparisons with European countries and give elements of evaluation and discussion on the performance of the Italian health care system.

Variations in the Survival of Adult Cancer Patients in Italy

Aims

As part of the ITACARE project, the present study analyzed and compared population-based data on the survival of adult cancer patients in Italy, according to sex, age, period of diagnosis and geographical area.

Methods

Nine Italian population-based cancer registries provided data on all their cancer patients (total 90,431 cases) followed for at least 5 years and diagnosed during the period 1978–1989. About 10% of the Italian population is covered by these registries. The data was analyzed by means of a multivariate model.

Results

The major findings were that there was a general improvement in 5-year relative survival over the study period (from 33% to 39%) and that there were significant differences in survival between different areas of the country, particularly for cancer sites which respond well to treatment. In general, the area covered by the Ragusa (Sicily) registry was characterized by significantly worse survival than other registry populations. Other important findings were that for all malignant cancer sites 5-year relative survival decreased with age from 50% for the youngest age class (15–44 years) to 27% for the oldest age class (75+ years) and that women have a better prognosis for most cancer sites (overall 5-year relative survival in women 48% vs 32% in men).

Conclusions

The significant regional differences in survival may reflect unequal provision of care, particularly between northern-central Italy and the south. The reasons for the general survival improvement with time are not completely understood, whereas the marked overall sex difference is related to the fact that the commonest cancer in women (breast cancer) is eminently more treatable than the commonest malignancy in men (lung cancer). The unfavorable trend with increasing age may be due to increasing difficulty in applying complete therapy protocols as general health declines, sometimes in relation to an advanced cancer stage at diagnosis.

A Global Cancer Surveillance Framework Within Noncommunicable Disease Surveillance: Making the Case for Population-Based Cancer Registries

The growing burden of cancer among several major noncommunicable diseases (NCDs) requires national implementation of tailored public health surveillance. For many emerging economies where emphasis has traditionally been placed on the surveillance of communicable diseases, it is critical to understand the specificities of NCD surveillance and, within it, of cancer surveillance. We propose a general framework for cancer surveillance that permits monitoring the core components of cancer control. We examine communalities in approaches to the surveillance of other major NCDs as well as communicable diseases, illustrating key differences in the function, coverage, and reporting in each system. Although risk factor surveys and vital statistics registration are the foundation of surveillance of NCDs, population-based cancer registries play a unique fundamental role specific to cancer surveillance, providing indicators of population-based incidence and survival. With an onus now placed on governments to collect these data as part of the monitoring of NCD targets, the integration of cancer registries into existing and future NCD surveillance strategies is a vital requirement in all countries worldwide. The Global Initiative for Cancer Registry Development, endorsed by the World Health Organization, provides a means to enhance cancer surveillance capacity in low- and middle-income countries.

A critical review of methods for assessing cancer survival disparities in indigenous population

PURPOSE

An increasing cancer burden among indigenous populations has led to a growing literature about survival disparities between indigenous and nonindigenous persons. We aim to describe and appraise methods used to measure cancer survival in indigenous persons in the United States, Canada, Australia, and New Zealand.

METHODS

We searched Medline, Web of Science, and EMBASE for articles published between 1990 and 2015 that estimated survival in populations indigenous to one of these four countries. We gathered information about data sources, analytical methods, and the extent to which threats to validity were discussed.

RESULTS

The search retrieved 83 articles. The most common approach to survival analysis was cause-specific survival (n = 49). Thirty-eight articles measured all-cause survival and 11 measured excess mortality attributable to cancer (relative survival). Three sources of information bias common to all studies (ethnic misclassification, incomplete case ascertainment, and incomplete death ascertainment) were acknowledged in a minority of articles.

CONCLUSIONS

The methodological considerations we present here are shared with studies of cancer survival across other subpopulations. We urge future researchers on this and related topics to clearly describe their data sources, to justify analytic choices, and to fully discuss the potential impact of those choices on the results and interpretation.

Comparability of stage data in cancer registries in six countries: lessons from the International Cancer Benchmarking Partnership

The International Cancer Benchmarking Partnership is investigating cancer survival differences between six high-income nations using population-based cancer registry data. Differences in overall survival are often explained by differences in the stage at diagnosis and stage-specific survival. Comparing stage at diagnosis using cancer registry data is challenging because of different regional practices in defining stage, despite the existence of international staging classifications such as TNM. This paper describes how stage data may be reconciled for international analysis. Population-based cancer registry data were collected for 2.4 million adults diagnosed with colorectal, lung, breast (women) or ovarian cancer during 1995-2007 in Australia, Canada, Denmark, Norway, Sweden and the United Kingdom. The stage data received were coded to a variety of international systems, including the TNM classification, Dukes' for colorectal cancer, FIGO for ovarian cancer, and to national "localised, regional, distant" categorisations. To optimise comparability for analysis, a rigorous and repeatable process was defined to produce a final stage variable for each patient. An algorithm was also defined to map TNM, Dukes' and FIGO to a "localised, regional, distant" categorisation. We recommend how stage data should be recorded and processed to optimise comparability in population-based international comparisons of stage-specific cancer outcomes. The process we describe to produce comparable stage data forms a benchmark for future research. The algorithm to convert between TNM and a "localised, regional, distant" categorisation should be valuable for international studies, until global consensus is achieved to adhere to a single staging system like TNM.

Cancer survival in Eastern and Western Germany after the fall of the iron curtain

Prior to the German reunification, cancer survival was much lower in East than in West Germany. We compare cancer survival between Eastern and Western Germany in the early twenty-first century, i.e. the second decade after the German reunification. Using data from 11 population-based cancer registries covering a population of 33 million people, 5-year age-standardized relative survival for the time period 2002-2006 was estimated for the 25 most common cancers using model-based period analysis. In 2002-2006, 5-year relative survival was very similar for most cancers, with differences below 3% units for 20 of 25 cancer sites. Larger, statistically significant survival advantages were seen for oral cavity, oesophagus, and gallbladder cancer and skin melanoma in the West and for leukemia in the East. Our study shows that within two decades after the assimilation of political and health care systems, the former major survival gap of cancer patients in Eastern Germany has been essentially overcome. This result is encouraging as it suggests that, even though economic conditions have remained difficult in Eastern Germany, comparable health care provision may nevertheless enable comparable levels of cancer survival within a relatively short period of time.

Survival from common and rare cancers in Germany in the early 21st century

BACKGROUND

Until recently, population-based data of cancer survival in Germany mostly relied on one registry covering ∼1 million people (1.3% of the German population). Here, we provide up-to-date cancer survival estimates for Germany based on data from 11 population-based cancer registries, covering 33 million people and compare them to survival estimates from the United States.

PATIENTS AND METHODS

Cancer patients diagnosed in 1997-2006 were included. Period analysis was employed to calculate 5-year relative survival for 38 cancers for 2002-2006. German and USA survival rates were compared utilizing the Surveillance, Epidemiology and End Results 13 database.

RESULTS

Five-year relative survival >80% was observed for testicular cancer (93.5%), skin melanoma (89.4%), cancers of the prostate (89.1%) and thyroid (87.8%), Hodgkin's lymphoma (84.5%) and cancers of the breast (83.7%) and endometrium (81.0%), which together account for almost 40% of cases. For the majority of cancers, German survival estimates were close to or below those in the United States. Exceptions with higher survival in Germany were cancers of the stomach, pancreas and kidney and Hodgkin's lymphoma.

CONCLUSIONS

German cancer survival estimates are mostly higher than the 2000-2002 pan-European estimates. Further research is needed to investigate causes responsible for differences between German and USA cancer survival rates.

Is detection of melanoma metastasis during surveillance in an early phase of development associated with a survival benefit?

Surveillance schedules in patients with cutaneous melanoma (CM) aim to detect metastatic spread in an early phase of development. Few studies investigated whether detection in an early phase is associated with prolonged survival and whether the observed longer survival times are a mere consequence of detection at an earlier time point (lead time bias). This is a long-term survival analysis of 1969 patients with stage I-III CM documented during 1996-1998 in the frame of a prospective surveillance study. Development of metastatic spread was detected in 112 patients during this period and classified as early phase or advanced phase based on tumor load and operability. The impact of lead time bias on differences in survival probabilities was examined using different statistical approaches. Of 59 patients with metastases detected in an early phase of development, 64.4% died of CM, of 43 patients with advanced phase metastases 86% died (P=0.013). The 10-year overall survival probability was 42.6% for early and 25.6% for advanced phase metastases (P=0.012). This comparison remained significant after adjustment for sojourn time. Multivariate analysis identified detection of early phase metastases (P=0.022) and stage at primary diagnosis (P<0.0001) as independent prognostic factors. In conclusion, this long-term follow-up study showed a factual gain in survival time for the detection of metastasis in an early phase of development beyond lead time bias. The classification of metastasis detected in early and advanced phase may be used in future studies aiming to improve melanoma surveillance.

What if cancer survival in Britain were the same as in Europe: how many deaths are avoidable?

Objective:

To estimate the number of deaths among cancer patients diagnosed in Great Britain that would be avoidable within 5 years of diagnosis if the mean (or highest) survival in Europe for patients diagnosed during 1985–1989, 1990–1994 and 1995–1999 were achieved.

Design:

Five-year relative survival for cancers in Great Britain compared with that from other countries in the EUROCARE-2, -3 and -4 studies. Calculation of excess deaths (those more than expected from mortality in the general population) that would be avoidable among cancer patients in Britain if relative survival were the same as in Europe.

Setting:

Great Britain (England, Wales, Scotland) and 13 other European countries.

Subjects:

2.8 million adults diagnosed in Britain with 1 of 39 cancers during 1985–1989 (followed up to 1994), 1990–1994 (followed up to 1999) and 1995–1999 (followed up to 2003).

Main outcome measure:

Annual number of avoidable deaths within 5 years of diagnosis. Percentage of the excess (cancer-related) deaths among cancer patients that would be avoidable.

Results:

Compared with the mean European 5-year relative survival, the largest numbers of avoidable deaths for patients diagnosed during 1985–1989 were for cancers of the breast (about 18% of the excess mortality from this cancer, 7541 deaths), prostate (14%, 4285), colon (9%, 4090), stomach (8%, 3483) and lung (2%, 3548). For 1990–1994, the largest numbers of avoidable deaths were for cancers of the prostate (20%, 7335), breast (15%, 6165), colon (9%, 4376), stomach (9%, 3672), lung (2%, 3735) and kidney (22%, 2644). For 1995–1999, most of the avoidable deaths were for cancers of the prostate (17%, 5758), breast (15%, 5475), lung (3%, 4923), colon (10%, 4295), stomach (9%, 3137) and kidney (21%, 2686).

Overall, some 6600–7500 premature deaths would have been avoided each year among cancer patients diagnosed in Britain during 1985–1999 if the mean survival in Europe had been achieved. This represents 6–7% of cancer-related mortality. Compared with the highest European survival, avoidable premature mortality among cancer patients fell from about 12 800 deaths a year (12.2% of cancer-related mortality) to about 11 400 deaths a year (10.6%) over the same period.

A large component of the avoidable mortality is due to prostate cancer: excluding this cancer from comparison with the European mean survival reduces the annual number of avoidable deaths by 1000–1500, and the percentage of excess mortality by up to 1%. Compared with the highest survival, the annual number of avoidable deaths would be 1500–2000 fewer, and 1–2% lower as a percentage of excess mortality, but the overall trend in avoidable premature mortality among cancer patients would be similar, falling from 11.4% (1985–1989) to 10.3% (1990–1994) and 9.7% for those diagnosed during 1995–1999.

For several cancers, survival in Britain was slightly higher than the mean survival in Europe; this represented some 110–180 premature deaths avoided each year during the period 1985–2003.

Conclusions:

Avoidable premature mortality among cancer patients diagnosed in Britain during 1985–1999 has represented 6–7% of cancer-related mortality compared with the mean survival in Europe. Compared with the highest levels of survival in Europe, the reduction from 12.2% to 10.6% of cancer-related mortality reflects small but steady progress over the period 1985–2003.

Interpreting trends in cancer patient survival

Data on cancer patient survival are an invaluable tool in the evaluation of therapeutic progress against cancer as well as other lethal diseases. As with all quantitative information routinely used in evidence-based clinical management--including diagnostic tests, prognostic markers and comparisons of therapeutic interventions--data on patient survival require evaluation based on an understanding of the underlying statistical methodology, methods of data collection and classification, and, most notably, clinical and biologic insight. This article contains an introduction to the methods used for estimating cancer patient survival, including cause-specific survival, relative survival and period analysis. The methods, and their interpretation, are illustrated through presentation of trends in incidence, mortality and patient survival for a range of different cancers. Our aim was to lay out the strengths and limitations of survival analysis as a tool in the evaluation of progress in the diagnosis and treatment of cancer.

Long-term survival probabilities for childhood rhabdomyosarcoma. A population-based evaluation

BACKGROUND

Evidence from clinical trials has documented improvements in event-free survival from childhood rhabdomyosarcoma (RMS) since the 1970s; however, the survival experience of children enrolled on cancer clinical trials may not reflect the full range of patients treated in community settings. The current study evaluated 5-year survival and 10-year conditional survival for RMS from U.S. population-based cancer registry data.

METHODS

Public-use data from the Surveillance, Epidemiology, and End Results (SEER) program were used in life table and Cox regression analyses to evaluate RMS survival by patient age at diagnosis, gender, tumor histology, tumor site and stage, and major treatment eras among 848 children who were age < 20 years at the time of diagnosis, were a resident of 1 of 9 geographic reporting regions, and were diagnosed between 1973 and 2000.

RESULTS

The 5-year survival probabilities were found to be highest for younger-age children (ages 1-4 years: 77%), patients with localized disease (83%), those whose tumors had an embryonal histology (67%), and patients with orbital (86%) and genitourinary (80%) tumor sites. Poor prognosis was associated with diagnosis during infancy (47%) and adolescence (48%); metastatic disease at the time of presentation (31%); alveolar histology (49%); and tumors of the extremities (50%), retroperitoneum (52%), and trunk (52%). Conditional 10-year survival probabilities among those who survived > or = 5 years were 85% or higher. The probability of survival by stage at the time of diagnosis increased with each successive treatment era, suggesting a stage shift phenomenon over time.

CONCLUSIONS

Large variations in 5-year survival were evident depending on patient age and tumor characteristics. However, children who survived the first 5 years after diagnosis were found to have an excellent long-term prognosis. The patterns in RMS survival noted from the current population-based evaluation did not appear to differ substantially from those previously reported by major clinical trials.

Survival patterns for the top four cancers in Canada: the effects of age, region and period

This study examined the variations in survival rates (1989-1991) and the trends (1969-1991), by sex, age and province, for patients diagnosed with breast, colorectal, lung or prostate cancer in Canada and compared the Canadian rates with those of nine American SEER registries. Five-year age-standardized relative survival rates (ASRs) were calculated, and the trends were estimated from variance-weighted linear regression of the ASRs for five periods of diagnosis (1969-1973, 1974-1978, 1979-1983, 1984-1988 and 1989-1991). In 1989-1991, the ASR varied among provinces for each cancer except female colorectal cancer. The lowest survival rates were observed in the youngest patients (15-44) for breast and prostate cancers, and in the oldest patients (75-99) of both sexes for lung and colorectal cancers. Over the five periods, a major trend toward improved survival was observed for breast, prostate and colorectal cancers (P<0.008), whereas no changes were seen for lung cancer. The ASRs in the western region were higher than in the Atlantic region over time (P<0.02) for each cancer. From the third period onward, the ASRs for Canadian patients with lung cancer were similar to those for the US patients and lower than for Canadian patients with breast, prostate or colorectal cancer. The observed increases in ASR for breast and prostate cancer are likely due to the increased use of screenings and the improved treatment modalities.

Técnicas de análise de sobrevida

As técnicas estatísticas conhecidas como análise de sobrevida são utilizadas quando se pretende analisar um fenômeno em relação a um período de tempo, isto é, ao tempo transcorrido entre um evento inicial, no qual um sujeito ou um objeto entra em um estado particular e um evento final, que modifica este estado. Assim, descrevem não só, como sugerido por seu nome, se os pacientes vivem ou morrem, mas também outros desfechos dicotômicos tais como recaída da doença, desmame do lactente etc. Neste trabalho são abordadas técnicas de análise de sobrevida, comparando-as e comentando sua utilização, especialmente na área oncológica. São ainda apresentados e discutidos os tipos de estudos epidemiológicos e de fontes de dados sujeitos a este tipo de análise. Faz-se a diferença entre estudos com base hospitalar ou de séries clínicas e estudos de base populacional, além de se discutir a interpretação dos resultados obtidos.

Cancer patient survival--patterns, comparisons, trends--a population-based Cancer Registry study in Finland

The effects of primary site, sex, age, stage and histological type on cancer patient survival were analysed on the basis of the population-based material of the Finnish Cancer Registry from 1985 to 1994. In addition, trends in survival were constructed for the period 1955-1994. Detailed site-specific data are published as Supplement 12 to Vol. 38 of Acta Oncologica. Within a given site, the survival differences by gender were not large. However, because of different site distributions, the average prognosis for female patients, all sites taken together, was superior to that of males: the 5-year relative survival rates (RSR) were 58% and 43%, respectively. In general, older patients had a poorer outcome compared with younger patients (partly because of different stage and histology distributions). Stage was a strong determinant of patient survival. In some cancers with a poor average prognosis the 5-year RSR for localized tumours was reasonable, e.g. 61% for stomach cancer, males, 34% for gallbladder cancer, females, and 29% for lung cancer, males. Most of the survival rates clearly increased over time. In addition to improvements in cancer treatment, changes over time in several other factors affect the trends, such as changes in the stage distribution (early diagnosis as a result of health education, improved diagnostic methods, screening, etc.) and in the composition of the patient material because of changing definitions of cancer (e.g. papilloma versus papillary carcinoma of the bladder, occult carcinoma of the thyroid, and early prostate cancer). The large Cancer Registry material (466,000 patients) enabled accurate estimates of the survival rates of cancer patients in Finland. These rates reflect the effectiveness of the healthcare system as a whole and are useful for planning and evaluation purposes. However, the estimated survival rates are based on grouped data, and cannot be directly applied for predicting the prognoses of individual patients, although they can be used as guidelines.

Survival of cancer patients in Finland 1955-1994

INTRODUCTION

The study of survival of cancer patients is essential for monitoring the effectiveness of cancer control. The previous monograph describing cancer patient survival in Finland was published by the Finnish Cancer Registry in 1981 and covered patients diagnosed in 1953-1974. This new supplement assesses cancer patient survival up to the year 1995.

MATERIAL AND METHODS

The study includes over 560000 tumours registered at the Finnish Cancer Registry with a date of diagnosis between 1955 and 1994. Patients were followed up to the end of 1995. Trends in relative survival rates are studied over four 10-year diagnostic periods from 1955 to 1994. In addition, detailed results are presented for patients diagnosed during 1985-1994, including relative survival rates tabulated by stage, sex, and age. Additional sections describe differences in cancer patient survival according to social class and region of residence and a comparison of cancer patient survival in Finland to other European countries.

RESULTS

Patient survival improved over time for almost all anatomical sites. The main exception is in cancer of the cervix uteri, where patient survival has decreased slightly from 1965-1974 to 1985-1994 due to the selective prevention of less aggressive tumours through cytologic screening. Very few differences in patient survival are observed between males and females. A substantial improvement in survival can be seen for childhood cancers.

CONCLUSION

The increasing survival rates reflect improvements that have taken place in various areas of cancer control, from health education and early diagnosis to treatment and aftercare. This study provides valuable reference information for both clinicians and health administrators, as well as a baseline for more detailed studies of patient survival for individual anatomical sites.

Improvement in survival of patients with cancer of the kidney in Europe. EUROCARE Working Group

Survival of adult patients with cancer of the kidney, renal pelvis, ureter and urethra (ICD-9 189) was analysed using data from the EUROCARE II study, a collaborative project of 45 population-based cancer registries in 17 European countries. For the period 1985-1989, more than 24000 patients were included and 5-year relative survival was 48%. Large variations were observed between countries with 5-year relative survival ranging from 57% in France, 53% in Italy and 51% in Spain to 35% in Denmark, 33% in Poland and 30% in Estonia. A number of registries also provided information on previous years and survival was seen to improve with time from 44% in 1978-1980 to 50% in 1987-1989. Age was an important determinant of survival with 5 year survival rates decreasing from 63% in patients aged 15-44 years to 36% in patients aged 75 years and older. Variation in survival rates by country or time is probably related to differences in the distribution of tumour stage at diagnosis. Evidence to confirm this theory is, however, lacking.

Introduction: the EUROCARE II Study

This introduction provides a general overview of the aims, methods and procedures used in the EUROCARE II study and the types of analyses presented in each article of this Special Issue of the European Journal of Cancer. The main aims of the EUROCARE II project are the updating of the survival database of the European Cancer Registries, the study of recent trends in relative survival rates and the interpretation of the survival differences observed both in time and across populations. Once having completed the preliminary stage of data checking, a total of 3,473,659 individual records from patients of all cancer sites, diagnosed between 1978 and 1989 and provided by 45 cancer registries in 17 European countries were accepted to build up the EUROCARE database. The quality of these data, in terms of the accuracy of the diagnosis and the validity of vital status assessment, was checked by indirect indicators, based on cross-validation analysis of consistency of the relevant variables. Statistical analysis was based on age-specific relative survival rates, computed for each cancer sites as the ratio of observed survival to the expected survival of the general population of the same area, gender and age, according to the Hakulinen method. An estimate of the European survival was computed as a weighted mean of the corresponding survival of the different countries, using as weights the expected yearly number of incident cases in each country. For comparison purposes, age-standardised survival was also calculated for Europe and for each country involved in the study.