For a sound use of health care data in epidemiology: evaluation of a calibration model for count data with application to prediction of cancer incidence in areas without cancer registry.

There is a growing interest in using health care (HC) data to produce epidemiological surveillance indicators such as incidence. Typically, in the field of cancer, incidence is provided by local cancer registries which, in many countries, do not cover the whole territory; using proxy measures from available nationwide HC databases would appear to be a suitable approach to fill this gap. However, in most cases, direct counts from these databases do not provide reliable measures of incidence. To obtain accurate incidence estimations and prediction intervals, these databases need to be calibrated using a registry-based gold standard measure of incidence. This article presents a calibration model for count data developed to predict cancer incidence from HC data in geographical areas without cancer registries. First, the ratio between the proxy measure and incidence is modeled in areas with registries using a Poisson mixed model that allows for heterogeneity between areas (calibration stage). This ratio is then inverted to predict incidence from the proxy measure in areas without registries. Prediction error admits closed-form expression which accounts for heterogeneity in the ratio between areas. A simulation study shows the accuracy of our method in terms of prediction and coverage probability. The method is further applied to predict the incidence of two cancers in France using hospital data as the proxy measure. We hope this approach will encourage sound use of the usually imperfect information extracted from HC data.

Performance of two formal tests based on martingales residuals to check the proportional hazard assumption and the functional form of the prognostic factors in flexible parametric excess hazard models.

Net survival, the one that would be observed if the disease under study was the only cause of death, is an important, useful, and increasingly used indicator in public health, especially in population-based studies. Estimates of net survival and effects of prognostic factor can be obtained by excess hazard regression modeling. Whereas various diagnostic tools were developed for overall survival analysis, few methods are available to check the assumptions of excess hazard models. We propose here two formal tests to check the proportional hazard assumption and the validity of the functional form of the covariate effects in the context of flexible parametric excess hazard modeling. These tests were adapted from martingale residual-based tests for parametric modeling of overall survival to allow adding to the model a necessary element for net survival analysis: the population mortality hazard. We studied the size and the power of these tests through an extensive simulation study based on complex but realistic data. The new tests showed sizes close to the nominal values and satisfactory powers. The power of the proportionality test was similar or greater than that of other tests already available in the field of net survival. We illustrate the use of these tests with real data from French cancer registries.

Incidence trends for potentially human papillomavirus-related and -unrelated head and neck cancers in France using population-based cancer registries data: 1980-2012.

Human papillomavirus (HPV) has been recently recognised as a carcinogenic factor for a subset of head and neck cancers (HNC). In Europe, France has one of the highest incidence rates of HNC. The aim of this study is to explore changes in HNC incidence in France, potentially in relation with infection by HPV. HNC were classified into two anatomical groups: potentially HPV-related and HPV-unrelated. Trends over the period 1980-2012 were analysed by an age-period-cohort model based on data from eleven French cancer registries. Among men, the age-standardised incidence rate (ASR) of HNC decreased in both groups, but less so for HPV-related sites as compared to unrelated sites, especially in recent years (annual percentage change [APC] over the period 2005-2012: -3.5% vs. -5.4%). Among women, the ASR increased in both groups, but more rapidly for HPV-related as compared to unrelated sites (APC over the period 2005-2012: +1.9% vs. -0.4%). This preferential growth of HPV-related versus unrelated HNC was observed in the cohorts born from 1930 to 1935. The differences in trends between possible HPV-related and HPV-unrelated sites suggest an increasing incidence of HNC due to HPV infection. The difference was less marked in men as compared to women, most likely because of a higher contamination in the HPV-related group by cancers due to tobacco or alcohol consumption. The pattern observed is consistent with observations made in other countries, with studies of HPV prevalence in HNC and the evolution of sexual behaviour in France.

Ovarian cancer in France: trends in incidence, mortality and survival, 1980-2012.

OBJECTIVE: The aim of this epidemiological study was to describe the incidence, mortality and survival of ovarian cancer (OC) in France, according to age, period of diagnosis, and histological type. METHODS: Incidence and mortality were estimated from 1980 to 2012 based on data in French cancer registries and from the Centre for Epidemiology of Causes of Death (CépiDc-Inserm) up to 2009. Net survival was estimated from registry data using the Pohar-Perme method, on cases diagnosed between 1989 and 2010, with date of last follow-up set at 30 June 2013. RESULTS: In 2012, 4615 cases of OC were diagnosed in France, and 3140 women died from OC. World population age-standardized incidence and mortality rates declined by respectively 0.6% and 1.2% per year between 1980 and 2012. Net survival at 5years increased slightly, from 40% for the period 1989-1993 to 45% for the period 2005-2010. Net survival varied considerably according to histological type. Germ cell tumors had better net survival at 10years (81%) compared to epithelial tumors (32%), sex cord-stromal tumors (40%) and tumors without biopsy (8%). CONCLUSIONS: Our study shows a decline in incidence and mortality rates from ovarian cancer in France between 1980 and 2012, but net survival remains poor overall, and improved only slightly over the whole study period.

Multidimensional penalized splines for survival models: illustration for net survival trend analyses.

BACKGROUND: In descriptive epidemiology, there are strong similarities between incidence and survival analyses. Because of the success of multidimensional penalized splines (MPSs) in incidence analysis, we propose in this pedagogical paper to show that MPSs are also very suitable for survival or net survival studies. METHODS: The use of MPSs is illustrated in cancer epidemiology in the context of survival trends studies that require specific statistical modelling. We focus on two examples (cervical and colon cancers) using survival data from the French cancer registries (cases 1990-2015). The dynamic of the excess mortality hazard according to time since diagnosis was modelled using an MPS of time since diagnosis, age at diagnosis and year of diagnosis. Multidimensional splines bring the flexibility necessary to capture any trend patterns while penalization ensures selecting only the complexities necessary to describe the data. RESULTS: For cervical cancer, the dynamic of the excess mortality hazard changed with the year of diagnosis in opposite ways according to age: this led to a net survival that improved in young women and worsened in older women. For colon cancer, regardless of age, excess mortality decreases with the year of diagnosis but this only concerns mortality at the start of follow-up. CONCLUSIONS: MPSs make it possible to describe the dynamic of the mortality hazard and how this dynamic changes with the year of diagnosis, or more generally with any covariates of interest: this gives essential epidemiological insights for interpreting results. We use the R package survPen to do this type of analysis.

Comparison of 2 Methods for Estimating Multiple Sclerosis-Related Mortality.

BACKGROUND AND OBJECTIVES: Determining whether multiple sclerosis (MS) causes death is challenging. Our objective was to contrast 2 frameworks to estimate probabilities of death attributed to MS (PMS) and other causes (Pother): the cause-specific framework (CSF), which requires the causes of death, and the excess mortality framework (EMF), which does not. METHODS: We used data from the Observatoire Français de la Sclérose en Plaques (OFSEP, n = 37,524) and from a comparative subset where causes of death were available (4,004 women with relapsing-onset MS [R-MS]). In CSF, the probabilities were estimated using the Aalen-Johansen method. In EMF, they were estimated from the excess mortality hazard, which is the additional mortality among patients with MS as compared with the expected mortality in the matched general population. PMS values were estimated at 30 years of follow-up, (1) with both frameworks in the comparative subset, by age group at onset, and (2) with EMF only in the OFSEP population, by initial phenotype, sex, and age at onset. RESULTS: In the comparative subset, the estimated 30-year PMS values were greater using EMF than CSF: 10.9% (95% CI 8.3-13.6) vs 8.7% (6.4-11.8) among the youngest and 20.4% (11.3-29.5) vs 16.2% (8.7-30.2) for the oldest groups, respectively. In the CSF, probabilities of death from unknown causes ranged from 1.5% (0.7-3.0) to 6.4% (2.5-16.4), and even after their reallocation, PMS values remained lower with CSF than with EMF. The estimated probabilities of being alive were close using the 2 frameworks, and the estimated POther (EMF vs CSF) was 2.6% (2.5-2.6) vs 2.1% (1.2-3.9) and 18.1% (16.9-19.3) vs 26.4% (16.5-42.2), respectively, for the youngest and oldest groups. In the OFSEP population, the estimated 30-year PMS values ranged from 7.5% (6.4-8.7) to 24.0% (19.1-28.9) in patients with R-MS and from 25.4% (21.1-29.7) to 36.8% (28.3-45.3) in primary progressive patients, depending on sex and age. DISCUSSION: EMF has the great advantage of not requiring death certificates, their quality being less than optimal. Conceptually, it also seems more relevant because it avoids having to state, for each individual, whether death was directly or indirectly caused by MS or whether it would have occurred anyway, which is especially difficult in such chronic diseases.

How to produce sound predictions of incidence at a district level using either health care or mortality data in the absence of a national registry: the example of cancer in France.

BACKGROUND: In many countries, epidemiological surveillance of chronic diseases is monitored by local registries (LR) which do not necessarily cover the whole national territory. This gap has fostered interest in using non-registry databases (e.g., health care or mortality databases) available for the whole territory as proxies for incidence at the local level. However, direct counts from these databases do not provide reliable incidence measures. Accordingly, specific methods are needed to correct proxies and assess their epidemiological usefulness. METHODS: This study's objective was to implement a three-stage turnkey methodology using national non-registry data to predict incidence in geographical areas without an LR as follows: constructing a calibration model to make predictions including accurate prediction intervals; accuracy assessment of predictions and rationale for the criteria to assess which predictions were epidemiologically useful; mapping after spatial smoothing of the latter predictions. The methodology was applied to a real-world setting, whereby we aimed to predict cancer incidence, by gender, at the district level in France over the 2007-15 period for 24 different cancer sites, using several health care indicators and mortality. In the present paper, the spatial smoothing performed on predicted incidence of epidemiological interest is illustrated for two examples. RESULTS: Predicted incidence of epidemiological interest was possible for 27/34 solid site-gender combinations and for only 2/8 haematological malignancies-gender combinations. Mapping of smoothed predicted incidence provided a clear picture of the main contrasts in incidence between districts. CONCLUSIONS: The methodology implemented provides a comprehensive framework to produce valuable predictions of incidence at a district level, using proxy measures and existing LR.

Effects of Age and Disease Duration on Excess Mortality in Patients With Multiple Sclerosis From a French Nationwide Cohort.

OBJECTIVE: To determine the effects of current age and disease duration on excess mortality in multiple sclerosis (MS), we describe the dynamics of excess death rates over these 2 time scales and study the effect of age at MS clinical onset on these dynamics, separately in each initial phenotype. METHODS: We used data from 18 French MS expert centers participating in the Observatoire Français de la Sclérose en Plaques. Patients with MS living in metropolitan France and having a clinical onset between 1960 and 2014 were included. Vital status was updated on January 1, 2016. For each MS phenotype separately (relapsing onset [RMS] or primary progressive [PPMS]), we used an innovative statistical method to model the logarithm of excess death rates by a multidimensional penalized spline of age and disease duration. RESULTS: Among 37,524 patients (71% women, mean age at MS onset ± SD 33.0 ± 10.6 years), 2,883 (7.7%) deaths were observed and 7.8% of patients were lost to follow-up. For patients with RMS, there was no excess mortality during the first 10 years after disease onset; afterwards, whatever the age at onset, excess death rates increased with current age. From current age 70, the excess death rate values converged and became identical whatever the age at disease onset, which means that disease duration had no more effect. Excess death rates were higher in men, with an excess hazard ratio of 1.46 (95% confidence interval 1.25-1.70). In contrast, in patients with PPMS, excess death rates rapidly increased from disease onset, and were associated with age at onset, but not with sex. CONCLUSIONS: In RMS, current age has a stronger effect on MS mortality than disease duration, while their respective effects are not clear in PPMS.

Multidimensional penalized splines for incidence and mortality-trend analyses and validation of national cancer-incidence estimates.

BACKGROUND: Cancer-incidence and mortality-trend analyses require appropriate statistical modelling. In countries without a nationwide cancer registry, an additional issue is estimating national incidence from local-registry data. The objectives of this study were to (i) promote the use of multidimensional penalized splines (MPS) for trend analyses; (ii) estimate the national cancer-incidence trends, using MPS, from only local-registry data; and (iii) propose a validation process of these estimates. METHODS: We used an MPS model of age and year for trend analyses in France over 1990-2015 with a projection up to 2018. Validation was performed for 22 cancer sites and relied essentially on comparison with reference estimates that used the incidence/health-care ratio over the period 2011-2015. Alternative estimates that used the incidence/mortality ratio were also used to validate the trends. RESULTS: In the validation assessment, the relative differences of the incidence estimates (2011-2015) with the reference estimates were <5% except for testis cancer in men and < 7% except for larynx cancer in women. Trends could be correctly derived since 1990 despite incomplete histories in some registries. The proposed method was applied to estimate the incidence and mortality trends of female lung cancer and prostate cancer in France. CONCLUSIONS: The validation process confirmed the validity of the national French estimates; it may be applied in other countries to help in choosing the most appropriate national estimation method according to country-specific contexts. MPS form a powerful statistical tool for trend analyses; they allow trends to vary smoothly with age and are suitable for modelling simple as well as complex trends thanks to penalization. Detailed trend analyses of lung and prostate cancers illustrated the suitability of MPS and the epidemiological interest of such analyses.

Deaths with asthma in France, 2000-2005: a multiple-cause analysis.

Mortality from asthma has decreased in many countries since the 1990s. Mortality statistics are usually based only on the underlying cause of death. The objectives of this study were to describe the characteristics of deaths and the trends in asthma-related mortality using multiple-cause analysis. Data were obtained from the French Centre of Epidemiology on Medical Causes of Death. Because ICD-10 was implemented in 2000, the analysis covers the period 2000-2005. In 2004-2005, asthma was the underlying cause of 42% of deaths with certificates mentioning asthma. The age-standardised rates of death from asthma decreased from 2000 through 2005 (-12% and -11%/year in the 1-44 and 45-64 age groups, respectively). The decline for all deaths with asthma was less pronounced (-9%/year in the 1-44 age group and -8%/year in the 45-64). Among adults aged 65 or older, the decrease in asthma-related mortality was higher in men (-12%/year for underlying cause, -9% for multiple-cause) than women (-5% and -3%, respectively). Since 2002, age-standardised rates of asthma-related mortality have been higher in women than men. In people aged 1-44 years, in-hospital deaths have declined between 2000 and 2005 while the proportion of non-hospital deaths increased from 53% to 67%. Regardless of the definition used, the age-standardised rate of asthma-related deaths decreased from 2000 to 2005, and the faster decline for underlying cause than for multiple-cause mortality argues for a real decline in mortality attributable to asthma. Using multiple cause-of-death analysis provides additional information for asthma mortality surveillance.

Trends in probabilities of death owing to cancer and owing to other causes in patients with colon cancer.

BACKGROUND: It is of interest to both the clinicians and patients to estimate the probability of death owing to cancer in the presence of other causes as time elapses since diagnosis. The objective of this study was to depict for patients diagnosed with colon cancer between 1990 and 2010 in France, the probability of surviving up to 10 years after diagnosis and to disentangle the probability of death owing to cancer from that of death owing to other causes. PATIENTS AND METHODS: Individuals with cancer were described, up to 10 years after diagnosis, as belonging to one of three categories: those who died owing to a cause related to cancer, those who died owing to another cause and those who survived. Net survival, crude probabilities of death related to colon cancer, death related to another cause and survival were estimated by modeling excess mortality hazard. RESULTS: In women of all ages, 5 and 10-year net survival improved over calendar time. The 10-year probability of survival decreased when age increased in both sexes. It was higher in women than in men, and this difference increased with age. Crude probabilities of death related to colon cancer decreased between 1990 and 2010 for men and women, although this was not observed in the eldest men. CONCLUSION: Crude probability of death related to colon cancer is an important indicator for patients and health policy makers. Results of cancer screening should be faced to trends in probability of death related to colorectal cancer.

Flexible and structured survival model for a simultaneous estimation of non-linear and non-proportional effects and complex interactions between continuous variables: Performance of this multidimensional penalized spline approach in net survival trend analysis.

Cancer survival trend analyses are essential to describe accurately the way medical practices impact patients' survival according to the year of diagnosis. To this end, survival models should be able to account simultaneously for non-linear and non-proportional effects and for complex interactions between continuous variables. However, in the statistical literature, there is no consensus yet on how to build such models that should be flexible but still provide smooth estimates of survival. In this article, we tackle this challenge by smoothing the complex hypersurface (time since diagnosis, age at diagnosis, year of diagnosis, and mortality hazard) using a multidimensional penalized spline built from the tensor product of the marginal bases of time, age, and year. Considering this penalized survival model as a Poisson model, we assess the performance of this approach in estimating the net survival with a comprehensive simulation study that reflects simple and complex realistic survival trends. The bias was generally small and the root mean squared error was good and often similar to that of the true model that generated the data. This parametric approach offers many advantages and interesting prospects (such as forecasting) that make it an attractive and efficient tool for survival trend analyses.

Lung cancer mortality in France. Trend analysis and projection between 1975 and 2012, using a Bayesian age-period-cohort model.

INTRODUCTION: Lung cancer is currently the most common cancer in the world and as such is an important public health concern. One of the main challenges is to foresee the evolution of trends in lung cancer mortality rates in order to anticipate the future burden of this disease as well as to plan the supply of adequate health care. The aim of this study is to propose a quantification of future lung cancer mortality rates by gender in France until the year 2012. METHODS: Lung cancer mortality data in France (1978-2002) were extracted from the National Statistics of Death and analyzed by 5-year age-groups and periods, using a Bayesian age-period-cohort model. DISCUSSION: Between 1978 and 2002, female lung cancer mortality rate rises by 3.3%year(-1). For men, a slow increase is observed until 1988-1992 followed by a declining trend. In 1998-2002, age-standardized mortality rates were, respectively, 45.5 and 7.6 per 100000 for males and for females. By 2008-2012 these figures would reach 40.8 (95% credibility interval (CI): 32.7, 50.0) and 12.1 (CI: 11.7, 12.6) per 100000, respectively, which represents among women a 4.7% annual increase (CI: 4.5, 5.0). RESULTS: Our results highlight the relevance of pursuing public health measures in order to cope more actively with tobacco smoking in the prevention strategy against lung cancer specifically among women.

Is breast cancer incidence increasing among young women? An analysis of the trend in France for the period 1983-2002.

The purpose of the study was to describe the trend in the incidence of breast cancer in women under 40 in France for the period 1983-2002 and compare it with the trend observed in other age groups. Data from seven cancer registries were analysed. Annual percentage changes were estimated in different age groups using Poisson regression. During the period 1983-2002, breast cancer incidence in women under 40 increased regularly, with an estimated annual percentage change of 0.65 (95% CI: 0.03-1.26). In women aged over 40, the increase is more significant, particularly among women aged 50-74 (2.93% per year). The increase in breast cancer incidence in women under 40 was low and steady over the 20-year period considered. Even though young women did not experience such a major change in diagnostic practices as the development of screening among women aged 50-74, it is difficult to distinguish the effects of possible changes in risk factors and in diagnostic practices in the slight increase observed.

Trends in net survival lung cancer in six European Latin countries: results from the SUDCAN population-based study.

Survival is a key measure of the effectiveness of a healthcare system. European Latin countries have some similarities in their health systems; it is thus interesting to examine their differences in survival from cancer, here, lung cancer. The aim of the SUDCAN collaborative study was to compare the trends in the 1- and 5-year net survival from lung cancer and the trends in the excess mortality rates between six European Latin countries (Belgium, France, Italy, Portugal, Spain and Switzerland). The data were extracted from the EUROCARE-5 database. First, the net survival was studied over the 2000-2004 period using Pohar-Perme estimator. For trend analyses, the study period was specific to each country. The results are reported from 1992 to 2004 in France, Italy, Spain and Switzerland and from 2000 to 2004 in Belgium and Portugal. The analyses were carried out using a flexible excess rate modelling. Overall, the 1-year net survival from lung cancer ranged between 36 (Spain) and 43% (Belgium and Switzerland) and the 5-year net survival ranged between 11 (Spain) and 15% (Belgium and Switzerland). Between 1992 and 2004, the age-standardized survival increased considerably at 1 year, but increased less at 5 years after diagnosis. This increase was observed at ages 60 and 70, but was less obvious at age 80. There was little difference in net survival from lung cancer between European Latin countries, particularly in the more recent years. However, survival was slightly lower in Spain and Portugal than in France, Italy, Belgium and Switzerland. High-resolution studies with data on treatment, stage at diagnosis and comorbidities are needed to understand the reasons for these differences.

Trends in net survival from skin malignant melanoma in six European Latin countries: results from the SUDCAN population-based study.

In Europe as a whole, survival from skin malignant melanoma (SMM) has increased constantly since the 1980s. The aim of the SUDCAN collaborative study was to compare the trends in the 5-year net survival from SMM and in related excess mortality rate between six European Latin countries (Belgium, France, Italy, Portugal, Spain, and Switzerland). The data were extracted from the EUROCARE-5 database (end of follow-up: 01 January 2009). First, the net survival was studied over the 2000-2004 period using the Pohar-Perme estimator. For trend analyses, the study period was specific to each country. The results are reported from 1992 to 2004 in France, Italy, Spain, and Switzerland and from 2000 to 2004 in Belgium and Portugal. The analyses were carried out using a flexible excess rate modeling. Over the 2000-2004 period, the 5-year net survival from SMM ranged from 79 (Portugal) to 90% (Switzerland). In all countries, net survival was higher in women versus men and in young versus old age groups. From 1992 to 2004, the 5-year net survival increased the most in the countries with the lowest survivals in 1992 (+9% in Italy and Spain vs. +2% in Switzerland or +4% in France). The differences between countries decreased between 1992 and 2004. Although survival increased to a lower or higher extent in all countries during the period studied, significant differences in net survival from SMM persisted among the six countries studied. Health policies should mainly enhance early diagnosis by increasing public awareness and with screening campaigns. Furthermore, new immunotherapies, which will be approved soon hopefully, should also be used to improve the outcomes of SMM treatment.

New insights into survival trend analyses in cancer population-based studies: the SUDCAN methodology.

The main objective of the SUDCAN study was to compare, for 15 cancer sites, the trends in net survival and excess mortality rates from cancer 5 years after diagnosis between six European Latin countries (Belgium, France, Italy, Portugal, Spain and Switzerland). The data were extracted from the EUROCARE-5 database. The study period ranged from 6 (Portugal, 2000-2005) to 18 years (Switzerland, 1989-2007). Trend analyses were carried out separately for each country and cancer site; the number of cases ranged from 1500 to 104 000 cases. We developed an original flexible excess rate modelling strategy that accounts for the continuous effects of age, year of diagnosis, time since diagnosis and their interactions. Nineteen models were constructed; they differed in the modelling of the effect of the year of diagnosis in terms of linearity, proportionality and interaction with age. The final model was chosen according to the Akaike Information Criterion. The fit was assessed graphically by comparing model estimates versus nonparametric (Pohar-Perme) net survival estimates. Out of the 90 analyses carried out, the effect of the year of diagnosis on the excess mortality rate depended on age in 61 and was nonproportional in 64; it was nonlinear in 27 out of the 75 analyses where this effect was considered. The model fit was overall satisfactory. We analysed successfully 15 cancer sites in six countries. The refined methodology proved necessary for detailed trend analyses. It is hoped that three-dimensional parametric modelling will be used more widely in net survival trend studies as it has major advantages over stratified analyses.

Focus on an unusual rise in pancreatic cancer incidence in France.

Background: Pancreatic cancer is one of the most lethal. Most countries have exhibited a stable or decreasing incidence over time. The aim of this study was to provide updated French temporal trends in pancreatic cancer incidence and mortality over the past three decades. Methods: Incidence was estimated using the French National Network of Cancer Registries (FRANCIM) and mortality using the French Mortality Statistics Office. World age-standardized incidence and mortality were modelled by age-period-cohort models. The net cumulative risk of developing pancreatic cancer by birth cohort was calculated, as were annual percentage changes (APCs) in incidence and mortality. Results: Between 1982 and 2012, age-standardized incidence increased from 4.8 in 1980 to 9.6 per 100 000 in men and from 2.3 to 6.8 in women. The mean APC was 2.3% (2.1-2.6) and 3.6% (3.3-3.9), respectively. The cumulative risk of developing pancreatic cancer before age 75 rose from 0.62% for males born around 1920 to 1.17% for those born around 1950. It was respectively 0.31% and 0.86% for women. Mortality did not vary in men (8.1 per 100 000). It slightly increased in women from 4.0 in 1982 to 5.4 in 2012. Conclusion: Pancreatic cancer incidence and mortality exhibited diverging trends. Incidence increased over the last 30 years in France whereas mortality did not vary in men and moderately increased in women. Incidence remained lower than mortality up to 2002. One cannot exclude the possibility that a similar trend may appear in other countries. Etiological studies are required to further explain this increase.

Trends in net survival from 15 cancers in six European Latin countries: the SUDCAN population-based study material.

The aim of the SUDCAN collaborative study was to compare the net survival from 15 cancers diagnosed in 2000-2004 in six European Latin countries and provide trends in net survival and dynamics of excess mortality rates up to 5 years after diagnosis from 1992 to 2004 in France, Italy, Spain, and Switzerland, and from 2000 to 2004 in Belgium and Portugal. This paper presents a detailed description of the data analyzed and quality indicators. Incident cases from Belgium, France, Italy, Portugal, Spain, and Switzerland were retrieved from 56 general or specialized population-based cancer registries that participated in the EUROCARE-5 database. Fifteen cancer sites were analyzed. The data were checked according to the EUROCARE protocol. The percentages of excluded cases, cases based on death-certificate only, cases lost to follow-up at 5 years after diagnosis, and the proportions of microscopically verified cases were evaluated across countries and cancer sites. Data exclusions for major flaws were negligible. Cases based on death-certificate only were quite rare, except for some poor-prognosis cancers in some countries. The site-specific proportions of microscopically verified cases were generally high, but slightly lower in Italy than elsewhere. The percentage of cases lost to follow-up at 5 years after diagnosis was generally low. The net survival analyses in 2000-2004 included 873 314 tumors, whereas trend analyses included 1 426 004 tumors. The quality of the data analyzed was generally good. In fact, the analyzed data have been already checked and accepted for EUROCARE-5. However, slight differences in quality indexes, for some cancers, should be kept in mind in the interpretation of survival comparisons across countries.

Trends in net survival from head and neck cancer in six European Latin countries: results from the SUDCAN population-based study.

The aim of the SUDCAN collaborative study was to compare the trends in 1- and 5-year net survival and the trends in the dynamics of the excess mortality rates in head and neck cancers between six European Latin countries (Belgium, France, Italy, Portugal, Spain and Switzerland). The data were extracted from the EUROCARE-5 database. First, the net survival was studied over the 2000-2004 period using the Pohar-Perme estimator. For trend analyses, the study period was specific to each country. The results are reported from 1992 to 2004 in France, Italy, Spain and Switzerland and from 2000 to 2004 in Belgium and Portugal. The analyses were carried out using a flexible excess rate modelling. There were significant differences between countries in 5-year age-standardized net survivals over the 2000-2004 period, ranging from 33 to 34% in France and Portugal from 42 to 44% in Switzerland and Italy, respectively. The age-standardized net survival improved considerably from 1992 to 2004 in Italy, Spain and Switzerland, but not in France because of lack of improvement in the elderly. The increase in net survival was linked to a decrease in the excess mortality rate up to 3-4 years after diagnosis. The net survival from head and neck cancers improved over the study period, but significant differences were still observed in 2004. Differences in sex ratio and anatomical distribution contributed only partially towards these disparities. Differences in stage at diagnosis, time to treatment and/or proportion of human papillomavirus-related cases are also probably involved in the survival disparities observed. Overall, the prognosis of these tumours remains poor.