Childhood cancer burden: a review of global estimates

5-year net survival of children and adolescents diagnosed with cancer is approximately 80% in many high-income countries. This estimate is encouraging as it shows the substantial progress that has been made in the diagnosis and treatment of childhood cancer. Unfortunately, scarce data are available for low-income and middle-income countries (LMICs), where nearly 90% of children with cancer reside, suggesting that global survival estimates are substantially worse in these regions. As LMICs are undergoing a rapid epidemiological transition, with a shifting burden from infectious diseases to non-communicable diseases, cancer care for all ages has become a global focus. To improve outcomes for children and adolescents diagnosed with cancer worldwide, an accurate appraisal of the global burden of childhood cancer is a necessary first step. In this Review, we analyse four studies of the global cancer burden that included data for children and adolescents. Each study used various overlapping and non-overlapping statistical approaches and outcome metrics. Moreover, to provide guidance on improving future estimates of the childhood global cancer burden, we propose several recommendations to strengthen data collection and standardise analyses. Ultimately, these data could help stakeholders to develop plans for national and institutional cancer programmes, with the overall aim of helping to reduce the global burden of cancer in children and adolescents.

Incidence of childhood cancer in Costa Rica, 2000-2014: An international perspective

BACKGROUND

Estimating childhood cancer incidence globally is hampered by a lack of reliable data from low- and middle-income countries. Costa Rica is one of the few middle-income countries (MIC) with a long-term high quality nationwide population-based cancer registry.

METHODS

Data on incident cancers in children aged under 15 years reported to the Costa Rica National Cancer Registry between 2000 and 2014 were analyzed by diagnostic group, age, sex, and geographical region and compared with incidence data for Hispanic and Non-Hispanic White (NHW) children in California, USA.

RESULTS

During the 15-year period, 2396 cases of childhood cancer were reported in Costa Rica, resulting in an overall age-standardized incidence rate (ASR) of 140/million. Most frequent cancer types were leukemias (40.5%), malignant central nervous system (CNS) tumors (13.9%), and lymphomas (12.7%). The observed ASR of lymphoid leukemia (46.9/million) ranked high globally. Low rates were found for most solid tumors including malignant CNS tumors, sympathetic nervous system tumors, and soft tissue sarcomas. There was almost no change in incidence rates over time, while geographical variations were observed within Costa Rica. The overall cancer rate in Costa Rica was lower compared to NHW (176.1/million) and Hispanic (161.7/million) children in California.

CONCLUSION

Based on the longstanding registration system, the childhood cancer incidence rates were similar to those observed in other Latin American countries. While a degree of under-ascertainment of cases cannot be excluded, the markedly high leukemia rates, in particular of the lymphoid sub-type deserves further study in this population.

Changing geographical patterns and trends in cancer incidence in children and adolescents in Europe, 1991-2010 (Automated Childhood Cancer Information System): a population-based study

BACKGROUND

A deceleration in the increase in cancer incidence in children and adolescents has been reported in several national and regional studies in Europe. Based on a large database representing 1·3 billion person-years over the period 1991-2010, we provide a consolidated report on cancer incidence trends at ages 0-19 years.

METHODS

We invited all population-based cancer registries operating in European countries to participate in this population-based registry study. We requested a listing of individual records of cancer cases, including sex, age, date of birth, date of cancer diagnosis, tumour sequence number, primary site, morphology, behaviour, and the most valid basis of diagnosis. We also requested population counts in each calendar year by sex and age for the registration area, from official national sources, and specific information about the covered area and registration practices. An eligible registry could become a contributor if it provided quality data for all complete calendar years in the period 1991-2010. Incidence rates and the average annual percentage change with 95% CIs were reported for all cancers and major diagnostic groups, by region and overall, separately for children (age 0-14 years) and adolescents (age 15-19 years). We examined and quantified the stability of the trends with joinpoint analyses.

FINDINGS

For the years 1991-2010, 53 registries in 19 countries contributed a total of 180 335 unique cases. We excluded 15 162 (8·4%) of 180 335 cases due to differing practices of registration, and considered the quality indicators for the 165 173 cases included to be satisfactory. The average annual age-standardised incidence was 137·5 (95% CI 136·7-138·3) per million person-years and incidence increased significantly by 0·54% (0·44-0·65) per year in children (age 0-14 years) with no change in trend. In adolescents, the combined European incidence was 176·2 (174·4-178·0) per million person-years based on all 35 138 eligible cases and increased significantly by 0·96% (0·73-1·19) per year, although recent changes in rates among adolescents suggest a deceleration in this increasing trend. We observed temporal variations in trends by age group, geographical region, and diagnostic group. The combined age-standardised incidence of leukaemia based on 48 458 cases in children was 46·9 (46·5-47·3) per million person-years and increased significantly by 0·66% (0·48-0·84) per year. The average overall incidence of leukaemia in adolescents was 23·6 (22·9-24·3) per million person-years, based on 4702 cases, and the average annual change was 0·93% (0·49-1·37). We also observed increasing incidence of lymphoma in adolescents (average annual change 1·04% [0·65-1·44], malignant CNS tumours in children (average annual change 0·49% [0·20-0·77]), and other tumours in both children (average annual change 0·56 [0·40-0·72]) and adolescents (average annual change 1·17 [0·82-1·53]).

INTERPRETATION

Improvements in the diagnosis and registration of cancers over time could partly explain the observed increase in incidence, although some changes in underlying putative risk factors cannot be excluded. Cancer incidence trends in this young population require continued monitoring at an international level.

FUNDING

Federal Ministry of Health of the Federal German Government, the European Union's Seventh Framework Programme, and International Agency for Research on Cancer.

The influence of prenatal exposure to trans-fatty acids for development of childhood haematopoietic neoplasms (EnTrance): a natural societal experiment and a case-control study

BACKGROUND

Little is known about the causes of childhood cancer, partly as not many children develop cancer, although childhood cancer is a leading cause of death by disease in the young. The young age of the children suggests that risk factors for childhood cancer may be present during pregnancy. Previous studies have shown that exposure to trans-fat, a type of unsaturated fat common in industrially produced foods (iTFA), has adverse health effects in adults, including the risk of developing cancer. Haematopoietic neoplasms are the most common cancer types among European children under the age of 15 years. This study will bring new knowledge as to whether trans-fat and other fatty acids may also increase the risk of developing haematopoietic neoplasms during childhood.

METHODS

We will investigate if the Danish iTFA legislation ban, which radically reduced the use of iTFA in foodstuffs, influenced the risk of childhood haematopoietic neoplasms in children born either before or after the change in legislation, adjusting for relevant secular trends. Further, in a case-control study, we will examine if levels of fatty acids in dried blood spots from newborns can predict the risk of developing childhood haematopoietic neoplasms. Permission from the Danish Data Protection Agency and the Ethical Committee has been granted.

DISCUSSION

The results from this study will provide important information about fatty acids in the mother's diet as a contributor to development of haematopoietic neoplasms during childhood, which may result in relevant preventive action.

TRIAL REGISTRATION

Not relevant.

Cancer incidence and mortality among young adults aged 20-39 years worldwide in 2012: a population-based study

BACKGROUND

To date, the burden of cancer among young adults has rarely been studied in depth. Our aim was to describe the scale and profile of cancer incidence and mortality worldwide among 20-39 year-olds, highlighting major patterns by age, sex, development level, and geographical region.

METHODS

We did a population-based study to quantify the burden of young adult cancers worldwide. We defined young adult cancers as those occurring between the ages of 20 and 39 years because these individuals will have passed puberty and adolescence, but not yet experienced the effects of hormonal decline, immune response deterioration, or organ dysfunction associated with chronic health conditions. Global, regional, and country-specific (n=184) data estimates of the number of new cancer cases and cancer-associated deaths that occurred in 2012 among young adults were extracted in four 5-year bands from the International Agency for Research on Cancer's GLOBOCAN 2012 for all cancers combined and for 27 major types as defined by the International Classification of Disease, tenth revision. We report the number of new cancer cases and cancer-associated deaths overall and by sex alongside corresponding age-standardised rates (ASR) per 100 000 people per year. We also present results using four levels of the Human Development Index (HDI; low [least developed], medium, high, and very high [most developed]), which is a composite indicator for socioeconomic development comprising life expectancy, education, and gross national income.

FINDINGS

975 396 new cancer cases and 358 392 cancer-associated deaths occurred among young adults worldwide in 2012, which equated to an ASR of 43·3 new cancer cases per 100 000 people per year and 15·9 cancer-associated deaths per 100 000 people per year. The burden was disproportionally greater among women and the most common cancer types overall in terms of new cases were female breast cancer, cervical cancer, thyroid cancer, leukaemia, and colorectal cancer; in terms of deaths, female breast cancer, liver cancer, leukaemia, and cervical cancer were the main contributors. When assessed by development level and geographical region, the cancer profile varied substantially; generally, the burden of infection-associated cancers was greater in regions under transition. Cancer incidence was elevated in very high-HDI regions compared with low-HDI regions (ASR 64·5 vs 46·2 cancer cases per 100 000 people per year); however, the mortality burden was 3 times higher in low-HDI regions (ASR 25·4 vs 9·2 cancer-associated deaths per 100 000 people per year), reflecting differences in cancer profiles and inferior outcomes.

INTERPRETATION

The global cancer burden among 20-39 year-olds differs from that seen in younger or older ages and varies substantially by age, sex, development level, and geographical region. Although the cancer burden is lower in this age group than that observed in older ages, the societal and economic effects remain great given the major effects of premature morbidity and mortality. Targeted surveillance, prevention, and treatment are needed to reduce the cancer burden in this underserved age group.

FUNDING

International Agency for Research on Cancer (IARC) and European Commission's FP-7 Marie Curie Actions-People-COFUND.

International incidence of childhood cancer, 2001-10: a population-based registry study

BACKGROUND

Cancer is a major cause of death in children worldwide, and the recorded incidence tends to increase with time. Internationally comparable data on childhood cancer incidence in the past two decades are scarce. This study aimed to provide internationally comparable local data on the incidence of childhood cancer to promote research of causes and implementation of childhood cancer control.

METHODS

This population-based registry study, devised by the International Agency for Research on Cancer in collaboration with the International Association of Cancer Registries, collected data on all malignancies and non-malignant neoplasms of the CNS diagnosed before age 20 years in populations covered by high-quality cancer registries with complete data for 2001-10. Incidence rates per million person-years for the 0-14 years and 0-19 years age groups were age-adjusted using the world standard population to provide age-standardised incidence rates (WSRs), using the age-specific incidence rates (ASR) for individual age groups (0-4 years, 5-9 years, 10-14 years, and 15-19 years). All rates were reported for 19 geographical areas or ethnicities by sex, age group, and cancer type. The regional WSRs for children aged 0-14 years were compared with comparable data obtained in the 1980s.

FINDINGS

Of 532 invited cancer registries, 153 registries from 62 countries, departments, and territories met quality standards, and contributed data for the entire decade of 2001-10. 385 509 incident cases in children aged 0-19 years occurring in 2·64 billion person-years were included. The overall WSR was 140·6 per million person-years in children aged 0-14 years (based on 284 649 cases), and the most common cancers were leukaemia (WSR 46·4), followed by CNS tumours (WSR 28·2), and lymphomas (WSR 15·2). In children aged 15-19 years (based on 100 860 cases), the ASR was 185·3 per million person-years, the most common being lymphomas (ASR 41·8) and the group of epithelial tumours and melanoma (ASR 39·5). Incidence varied considerably between and within the described regions, and by cancer type, sex, age, and racial and ethnic group. Since the 1980s, the global WSR of registered cancers in children aged 0-14 years has increased from 124·0 (95% CI 123·3-124·7) to 140·6 (140·1-141·1) per million person-years.

INTERPRETATION

This unique global source of childhood cancer incidence will be used for aetiological research and to inform public health policy, potentially contributing towards attaining several targets of the Sustainable Development Goals. The observed geographical, racial and ethnic, age, sex, and temporal variations require constant monitoring and research.

FUNDING

International Agency for Research on Cancer and the Union for International Cancer Control.

Paediatric cancer stage in population-based cancer registries: the Toronto consensus principles and guidelines

Population-based cancer registries generate estimates of incidence and survival that are essential for cancer surveillance, research, and control strategies. Although data on cancer stage allow meaningful assessments of changes in cancer incidence and outcomes, stage is not recorded by most population-based cancer registries. The main method of staging adult cancers is the TNM classification. The criteria for staging paediatric cancers, however, vary by diagnosis, have evolved over time, and sometimes vary by cooperative trial group. Consistency in the collection of staging data has therefore been challenging for population-based cancer registries. We assembled key experts and stakeholders (oncologists, cancer registrars, epidemiologists) and used a modified Delphi approach to establish principles for paediatric cancer stage collection. In this Review, we make recommendations on which staging systems should be adopted by population-based cancer registries for the major childhood cancers, including adaptations for low-income countries. Wide adoption of these guidelines in registries will ease international comparative incidence and outcome studies.

Cancer Incidence in Five Continents: Inclusion criteria, highlights from Volume X and the global status of cancer registration

Cancer Incidence in Five Continents (CI5), a longstanding collaboration between the International Agency for Research on Cancer and the International Association of Cancer Registries, serves as a unique source of cancer incidence data from high-quality population-based cancer registries around the world. The recent publication of Volume X comprises cancer incidence data from 290 registries covering 424 populations in 68 countries for the registration period 2003-2007. In this article, we assess the status of population-based cancer registries worldwide, describe the techniques used in CI5 to evaluate their quality and highlight the notable variation in the incidence rates of selected cancers contained within Volume X of CI5. We also discuss the Global Initiative for Cancer Registry Development as an international partnership that aims to reduce the disparities in availability of cancer incidence data for cancer control action, particularly in economically transitioning countries, already experiencing a rapid rise in the number of cancer patients annually.

Childhood central nervous system tumour mortality and survival in Southern and Eastern Europe (1983-2014): Gaps persist across 14 cancer registries

AIM

Childhood central nervous system (CNS) tumour registration and control programs in Southern and Eastern Europe remain thin, despite the lethal nature of the disease. Mortality/survival data were assembled to estimate the burden of malignant CNS tumours, as well as the potential role of sociodemographic survival determinants across 14 cancer registries of this region.

METHODS

Average age-adjusted mortality rates were calculated, whereas time trends were quantified through Poisson and Joinpoint regressions. Kaplan-Meier curves were derived for the maximum and the more recent (10 and 5 year) registration periods. Multivariate Cox regression models were used to assess demographic and disease-related determinants.

RESULTS

Variations in mortality (8-16 per million) and survival (5-year: 35-69%) were substantial among the participating registries; in most registries mortality trend was stable, whereas Bulgaria, having the highest starting rate, experienced decreasing annual mortality (-2.4%, p=0.001). A steep decrease in survival rates was evident before the second year of follow-up. After controlling for diagnostic subgroup, age, gender and diagnostic year, Greece seemed to present higher survival compared with the other contributing registries, although the follow-up period was short. Irrespective of country, however, rural residence was found to impose substantial adverse repercussions on survival (hazard ratio (HR): 1.2, 95% confidence interval (CI): 1.1-1.4).

CONCLUSION

Cross-country mortality and survival variations possibly reflect suboptimal levels of health care delivery and cancer control in some regions of Southern and Eastern Europe, notwithstanding questionable death certification patterns or follow-up procedures. Continuous childhood cancer registration and linkage with clinical data are prerequisite for the reduction of survival inequalities across Europe.

Childhood central nervous system tumours: Incidence and time trends in 13 Southern and Eastern European cancer registries

AIM

Following completion of the first 5-year nationwide childhood (0-14 years) registration in Greece, central nervous system (CNS) tumour incidence rates are compared with those of 12 registries operating in 10 Southern-Eastern European countries.

METHODS

All CNS tumours, as defined by the International Classification of Childhood Cancer (ICCC-3) and registered in any period between 1983 and 2014 were collected from the collaborating cancer registries. Data were evaluated using standard International Agency for Research on Cancer (IARC) criteria. Crude and age-adjusted incidence rates (AIR) by age/gender/diagnostic subgroup were calculated, whereas time trends were assessed through Poisson and Joinpoint regression models.

RESULTS

6062 CNS tumours were retrieved with non-malignant CNS tumours recorded in eight registries; therefore, the analyses were performed on 5191 malignant tumours. Proportion of death certificate only cases was low and morphologic verification overall high; yet five registries presented >10% unspecified neoplasms. The male/female ratio was 1.3 and incidence decreased gradually with age, apart from Turkey and Ukraine. Overall AIR for malignant tumours was 23/10(6) children, with the highest rates noted in Croatia and Serbia. A statistically significant AIR increase was noted in Bulgaria, whereas significant decreases were noted in Belarus, Croatia, Cyprus and Serbia. Although astrocytomas were overall the most common subgroup (30%) followed by embryonal tumours (26%), the latter was the predominant subgroup in six registries.

CONCLUSION

Childhood cancer registration is expanding in Southern-Eastern Europe. The heterogeneity in registration practices and incidence patterns of CNS tumours necessitates further investigation aiming to provide clues in aetiology and direct investments into surveillance and early tumour detection.

Uses of cancer registries for public health and clinical research in Europe: Results of the European Network of Cancer Registries survey among 161 population-based cancer registries during 2010-2012

AIM

To provide insight into cancer registration coverage, data access and use in Europe. This contributes to data and infrastructure harmonisation and will foster a more prominent role of cancer registries (CRs) within public health, clinical policy and cancer research, whether within or outside the European Research Area.

METHODS

During 2010-12 an extensive survey of cancer registration practices and data use was conducted among 161 population-based CRs across Europe. Responding registries (66%) operated in 33 countries, including 23 with national coverage.

RESULTS

Population-based oncological surveillance started during the 1940-50s in the northwest of Europe and from the 1970s to 1990s in other regions. The European Union (EU) protection regulations affected data access, especially in Germany and France, but less in the Netherlands or Belgium. Regular reports were produced by CRs on incidence rates (95%), survival (60%) and stage for selected tumours (80%). Evaluation of cancer control and quality of care remained modest except in a few dedicated CRs. Variables evaluated were support of clinical audits, monitoring adherence to clinical guidelines, improvement of cancer care and evaluation of mass cancer screening. Evaluation of diagnostic imaging tools was only occasional.

CONCLUSION

Most population-based CRs are well equipped for strengthening cancer surveillance across Europe. Data quality and intensity of use depend on the role the cancer registry plays in the politico, oncomedical and public health setting within the country. Standard registration methodology could therefore not be translated to equivalent advances in cancer prevention and mass screening, quality of care, translational research of prognosis and survivorship across Europe. Further European collaboration remains essential to ensure access to data and comparability of the results.

Towards optimal clinical and epidemiological registration of haematological malignancies: Guidelines for recording progressions, transformations and multiple diagnoses

Haematological malignancies (HM) represent over 6% of the total cancer incidence in Europe and affect all ages, ranging between 45% of all cancers in children and 7% in the elderly. Thirty per cent of childhood cancer deaths are due to HM, 8% in the elderly. Their registration presents specific challenges, mainly because HM may transform or progress in the course of the disease into other types of HM. In the context of cancer registration decisions have to be made about classifying subsequent notifications on the same patient as the same tumour (progression), a transformation or a new tumour registration. Allocation of incidence date and method of diagnosis must also be standardised. We developed European Network of Cancer Registries (ENCR) recommendations providing specific advice for cancer registries to use haematology and molecular laboratories as data sources, conserve the original date of incidence in case of change of diagnosis, make provision for recording both the original as well as transformed tumour and to apply precise rules for recording and counting multiple diagnoses. A reference table advising on codes which reflect a potential transformation or a new tumour is included. This work will help to improve comparability of data produced by population-based cancer registries, which are indispensable for aetiological research, health care planning and clinical research, an increasing important area with the application of targeted therapies.

Registration of childhood cancer: Moving towards pan-European coverage?

Cancer is relatively rare in childhood, but it contributes considerably to childhood mortality, years of life lost per person and late effects in survivors. Large populations need to be covered to set up meaningful studies of these rare conditions. Cancer registries ensure cancer surveillance, thus providing the basis for research as well as policy decisions. In this paper we examine coverage of childhood population by cancer registries in Europe and encourage national cancer registration. Over 200 cancer registries in various stages of development were identified as collecting data on childhood cancer patients in Europe. They cover 52% of the childhood population in the World Health Organisation (WHO) European region and 83% in the European Union (EU). More than 80% of this coverage is ensured by nationwide data collection, which is ongoing in 29 European countries. Overall coverage of the childhood population could increase to around 98%, if the recently established cancer registries start producing results and others improve their quality and dissemination plans. Paediatric cancer registries are being established with increasing frequency even in the areas covered by general cancer registries, and they tend to be national. Compared with regional registration, national cancer registries are more cost-effective, record larger number of cases, they can achieve higher completeness, less biased incidence and survival estimates and they are conditioned for national and international research. National registration of childhood cancer should be the rule in Europe, so that accurate regional, nation-wide and international statistics can provide solid baselines for research, clinical practice and public health policy. Governmental support and stakeholders' involvement are indispensable to guarantee optimal data quality and completeness.

The European Cancer Observatory: A new data resource

Population-based cancer registries provide indispensable information on cancer incidence and survival, which cannot be obtained by any other means. It is clear that complete and effective use of these data is essential for cancer control, but sharing this information in a uniform, timely and user-friendly manner has been somewhat limited up to now. The European Cancer Observatory (ECO, http://eco.iarc.fr) has been developed in the framework of the EUROCOURSE project (EUROpe against Cancer: Optimisation of Use of Registries for Scientific Excellence in Research) as a comprehensive resource combining all the information currently available in Europe on cancer incidence, mortality, survival and prevalence. The website provides analytical and presentation tools to examine national estimates for 2012 in 40 European countries (EUCAN), data for 130 national or sub-national areas covered by cancer registries for up to 60 years, until 2011 (EUREG) and a planned mechanism for data download (European Cancer Incidence and Mortality (EUROCIM)). The generated statistics outline the considerable variability across Europe in the rates of all major cancer types and help identify key concerns that need to be addressed by public health policies e.g. the unprecedented rise of lung cancer incidence in women with its full impact expected within a decade or so. The support, maintenance and further development of the ECO website should be a high priority for European cancer policymakers, to continue providing this unique information to health professionals, researchers and the general public in Europe and beyond.