The impact of under-reporting of cases on the estimates of childhood cancer incidence and survival in Estonia

Incidence, survival, and mortality of cancer in children and young adolescents in Belgium and the Netherlands in 2004-2015: A comparative population-based study

International comparisons of cancer surveillance measures may provide insight into inequalities in registration practices, etiological factors, and treatment strategies. This study aimed to compare incidence, survival, and mortality of cancer in children and young adolescents between Belgium and the Netherlands. All children (0-14 years) and young adolescents (15-17 years) diagnosed with cancer between 2004 and 2015 were selected from the population-based cancer registries of Belgium (N = 4739) and the Netherlands (N = 7322). Differences in incidence and mortality were expressed as standardized rate ratios (SRR; BE/NL). Five-year observed survival was calculated using the Kaplan-Meier method. During 2004-2015, the overall cancer incidence among children and young adolescents was similar in both countries. Incidence of neuroblastoma was significantly higher in Belgian children (2010-2015: SRR = 1.3, 95% CI 1.0-1.6). Five-year survival of all malignant cancers was comparable in 2010-2015, exceeding 80% in both age groups. Remarkable differences in survival existed in children for malignant central nervous system (CNS) tumors in 2004-2009 (BE = 62%, NL = 45%), for acute myeloid leukemia (BE = 68%, NL = 78%) and rhabdomyosarcomas (BE = 60%, NL = 79%) in 2010-2015, and for neuroblastoma in both periods (2004-2009: BE = 76%, NL = 64%; 2010-2015: BE = 82%, NL = 64%). Overall cancer mortality in children decreased by approximately 3 percent-points annually in both countries, but was slightly lower in Belgium in 2004-2009 (SRR = 0.9, 95% CI 0.7-1.0). Despite differences for specific cancer types, overall cancer incidence, survival, and mortality were comparable between Dutch and Belgian children and young adolescents in 2010-2015. Variability in screening, diagnosis, and registration practices probably explains the observed differences in incidence and survival of neuroblastoma and malignant CNS tumors.

The impact of incomplete registration on survival rate of children with very rare tumors

Pediatric very rare tumors (VRTs) represent a heterogeneous subset of childhood cancers, with reliable survival estimates depending dramatically on each (un)registered case. The current study aimed to evaluate the number of VRTs among Lithuanian children, to assess the impact of the registration status on survival rates and to track changes in treatment outcomes over the 16-year study period. We performed a population-based retrospective study across children below 18 years old diagnosed with VRTs in Lithuania between the years 2000 and 2015. The identified cases were cross-checked with the Lithuanian Cancer Registry—a population-based epidemiology cancer registry—for the fact of registration and survival status. The overall survival was calculated in relation to the registration status and treatment period. Thirty-seven children with VRTs were identified within the defined time frame. Six of them (16.2%) were not reported to the Lithuanian Cancer Registry at diagnosis. The probability of overall survival at 5 years (OS_5y) differed significantly between the registered (n = 31) and unregistered (n = 6) cohorts: 51.6% versus 100%, respectively (p = 0.049). A 5-year survival estimate for children diagnosed with a VRT at the age of 0–14 years differed by 10 percentage points according to the registration completeness: 52.1% calculated for the entire cohort versus 42.1% for registered patients only. The OS_5y has not improved over the analyzed period: 61.1% in 2000–2007 versus 57.9% in 2008–2015 (p = 0.805). The survival continued to decline beyond 5 years post-diagnosis due to late cancer-related adverse events: 59.5% of patients were alive at 5 years as compared to 44.3% at 10 years. The OS_5y of children affected by VRT was lower than in more common childhood cancers. The survival rate of the unregistered patients may lead to misinterpretation of treatment outcomes. Meticulous registration of VRTs is crucial for correct evaluation of treatment outcomes, especially across small countries with few cases.

28-year incidence and time trends of childhood leukaemia in former East Germany compared to West Germany after German reunification: A study from the German Childhood Cancer Registry

BACKGROUND

The aetiology of childhood leukaemia is largely unknown. Analyses of geographical differences may enhance aetiologic insights. The reunification of Germany in 1990 provides a unique opportunity to evaluate incidence patterns and time trends in two merging countries with substantial lifestyle, social and socioeconomic differences. With this study we provide an extensive assessment of 28-year incidence patterns and temporal trends after the German reunification.

METHODS

We identified all children diagnosed with a lymphoid leukaemia (LL) or acute myeloid leukaemia (AML) before the age of 15 years between 1991 and 2018 using the German Childhood Cancer Registry (N = 14,922), and evaluated the incidence pattern and temporal trends in former East Germany compared to West Germany by subtype, age at diagnosis and sex.

RESULTS

Incidence rates of LL were substantially lower (around 20 %) in Eastern Germany compared to Western Germany at the time of reunification. This was followed by a remarkable increase in Eastern Germany across both sexes and age groups until around 2000, when incidence rates reached the same levels as those in Western German federal states. Thereafter, incidence rates remained rather stable with some indications of a slightly decreasing tendency in both Eastern and Western Germany (estimated annual percentage changes (EAPC) 2005-2018: East Germany = -0.8 %; West Germany = -0.4 %), driven by the 0- to 4-year olds. Overall, AML incidence rates were stable over time in Western Germany, while EAPC for Eastern Germany indicated an increasing tendency (EAPC 1991-2018 = 1.3 %) driven by the older children, mostly during the early 2000s and in most recent years.

CONCLUSION

The underlying mechanisms driving the childhood leukaemia rates remain inconclusive. Linkage studies including individual and clinical data would be valuable in evaluating the impact of a population's social, socioeconomic and lifestyle changes on the risk of childhood leukaemia and disease aetiology overall.

Improvement in childhood cancer survival in Lithuania over three decades

Background

Population-based EUROCARE-5 studies demonstrated that childhood cancer survival rates in Lithuania were 10-20% lower than the European mean. We aimed to analyse the change in the outcome of treatment of paediatric malignancies in Lithuania over 30 years.

Methods

A single-centre retrospective analysis of children below 18 years of age treated for cancer at Vilnius University Hospital Santaros Klinikos between 1982 and 2011 was carried out. The minimal requirement of 5-year follow-up after diagnosis was specified for survival estimation. The vital status was assessed using data from the population-based Lithuanian Cancer Registry. To evaluate changes over time, the entire cohort was split into three groups according to the time of diagnosis: 1982-1991, 1992-2001, and 2002-2011.

Results

A total of 1268 children met the inclusion criteria. The shortest median follow-up was 8.9 (IQR 6.4-11.5) years for patients treated in the third decade. The 5-year overall survival of the entire cohort increased from 37.3% (95% CI 30.2-44.3) in 1982-1991 to 70.7% (95% CI 66.4-74.1) in 2002-2011 (p < 0.0001). The same trend was evident when calculated separately for leukaemia (p < 0.0001), lymphoma (p < 0.0005), and solid tumours (p < 0.004). The percentage of cure rose from zero in the early years of the period analysed to 80% in 2010 and 2011. The improvement in the treatment outcome was attributable to the reduction of treatment-related mortality from 45.8% in 1982-1991 to 12.4% in 2002-2011 and disease recurrence from 30.4% to 19.6% for the same periods, respectively.

Conclusions

Significant progress in the cure rate of children treated for cancer at our institution was observed over 30 years. Collaborative national and international clinical and research efforts are crucial to ensure further advances in care and cure.

Childhood cancer incidence and survival trends in Estonia (1970-2016): a nationwide population-based study

Background

Childhood cancers represent a small proportion of all cancers but are still a major public health problem. The study analysed long-term trends in childhood cancer incidence and survival in Estonia in relation to societal and health care transition.

Methods

Data on all malignant tumours, diagnosed in children aged 0–14 during 1970–2016, were derived from the Estonian Cancer Registry. Age-standardised (World standard) incidence rates were calculated by ICCC-3 site groups and joinpoint regression was used to estimate annual percentage change (APC) for incidence trends. Cohort and period approach were used to estimate 5-year survival. Internal age standardisation was applied.

Results

A total of 1628 incident cancer cases were diagnosed during the study period and overall incidence increased significantly at a rate of 0.5% per year. Significant increases were seen for neuroblastoma and germ cell tumours, for lymphoid leukemias and some CNS sub-sites. At the same time, decline in incidence was seen in almost all subgroups of unspecified neoplasms. The overall 5-year survival improved from 24% in 1970–1979 to 73% in 2010–2016, with the largest changes occurring in the 1990s and 2000s. For many sites, survival increase thereafter has been marginal.

Conclusion

In this first comprehensive population-based study of childhood cancer incidence and survival in Estonia, long-term trends are shown in the context of societal and health care changes. Even though the increasing incidence of some sites may, at least partially, be explained by improved diagnostics reflected in the decreased incidence of unspecified neoplasms, the overall cancer incidence in children seems to be rising. Rapid progress in diagnosis and care have improved childhood cancer survival immensely, but deficit in Estonia persists compared to other European countries. Results of the study accentuate the need for a more in-depth analysis of clinical data, but also for the prioritization of childhood cancer in Estonia, to ensure access to standard care and innovative treatments.

Ascertainment of cancer in longitudinal research: The concordance between the Rotterdam Study and the Netherlands Cancer Registry

Complete and accurate registration of cancer is needed to provide reliable data on cancer incidence and to investigate aetiology. Such data can be derived from national cancer registries, but also from large population‐based cohort studies. Yet, the concordance and discordance between these two data sources remain unknown. We evaluated completeness and accuracy of cancer registration by studying the concordance between the population‐based Rotterdam Study (RS) and the Netherlands Cancer Registry (NCR) between 1989 and 2012 using the independent case ascertainment method. We compared all incident cancers in participants of the RS (aged ≥45 years) to registered cancers in the NCR in the same persons based on the date of diagnosis and the International Classification of Diseases (ICD) code. In total, 2,977 unique incident cancers among 2,685 persons were registered. Two hundred eighty‐eight cancers (9.7%) were coded by the RS that were not present in the NCR. These were mostly nonpathology‐confirmed lung and haematological cancers. Furthermore, 116 cancers were coded by the NCR, but not by the RS (3.9%), of which 20.7% were breast cancers. Regarding pathology‐confirmed cancer diagnoses, completeness was >95% in both registries. Eighty per cent of the cancers registered in both registries were coded with the same date of diagnosis and ICD code. Of the remaining cancers, 344 (14.5%) were misclassified with regard to date of diagnosis and 72 (3.0%) with regard to ICD code. Our findings indicate that multiple sources on cancer are complementary and should be combined to ensure reliable data on cancer incidence.

What's new?

While national cancer registries and population‐based cohort studies are the primary sources of data on cancer risk and incidence, the degree to which these data sets are concordant remains unknown. In this investigation, the authors evaluated concordance between the population‐based Rotterdam Study and the Netherlands Cancer Registry. The two data sets were highly concordant for pathology‐confirmed cancers and cancer site. Non‐pathology‐confirmed cancers, however, were under‐registered in the Netherlands Cancer Registry, potentially resulting in underestimation of cancer incidence. The findings highlight the important role that different sources of cancer diagnosis registration serve in providing reliable estimates of cancer incidence.