Population-based incidence of childhood leukaemias and lymphomas in Spain (1993-2002)

Incidence and time trends of childhood hematological neoplasms: a 36-year population-based study in the southern European context, 1983-2018

BACKGROUND

Hematological neoplasms (HNs) are the first and most common childhood cancers globally. Currently, there is a lack of updated population-based data on the incidence of these cancers in the Spanish pediatric population. This study aimed to describe the incidence and incidence trends of HNs in children (0-14 years) in Spain using data from the Spanish Network of Cancer Registries and to compare the results with other southern European countries.

METHODS

Data were extracted from 15 Spanish population-based cancer registries between 1983 and 2018. Cases were coded according to the International Classification of Diseases for Oncology, third edition, first revision, and grouped according to the International Classification of Childhood Cancer, third edition. Crude rates (CRs), age-specific rates, and age-standardized incidence rates using the 2013 European population (ASRE) were calculated and expressed as cases per 1,000,000 child-years. Incidence trends and annual percentage changes (APCs) were estimated.

RESULTS

A total of 4,747 HNs were recorded (59.5% boys). Age distribution [n (%)] was as follows: <1 year, 266 (5.6%); 1-4 years, 1,726 (36.4%); 5-9 years, 1,442 (30.4%); and 10-14 years, 1,313 (27.6%). Leukemias were the most common group, with a CR and an ASRE of 44.0 (95%CI: 42.5; 45.5) and 44.1 (95%CI: 42.6; 45.7), respectively. The CR and ASRE of lymphomas were 20.1 (95%CI: 19.1; 21.1) and 20.0 (95%CI: 19.0; 21.1), respectively. The comparable incidence rates between our results and those of other southern European countries were similar for lymphomas, while some differences were observed for leukemias. From 1988 to 2016, the trend in leukemia incidence was stable for both sexes, with an APC of 0.0 (95%CI: -0.5; 0.7), whereas a constant overall increase was observed for lymphoma in both sexes, with an APC of 1.0 (95%CI: 0.4; 1.6).

CONCLUSION

Leukemias are the most common HNs in children, and their incidence has remained stable since 1988, whereas the incidence of lymphomas has increased every year. Lymphoma incidence is like that of other southern European countries, while leukemia incidence is similar only to that of southwestern European countries. Collaborative cancer registry projects allow for assessing epidemiological indicators for cancers such as HNs, which helps health authorities and clinicians provide more knowledge about these malignancies.

Pediatric Acute Promyelocytic Leukemia: Epidemiology, Molecular Features, and Importance of GST-Theta 1 in Chemotherapy Response and Outcome

Previous studies have suggested a variation in the incidence of acute promyelocytic leukemia (APL) among the geographic regions with relatively higher percentages in the Latin American population. We aimed to explore the population burden of pediatric APL, gathering information from the population-based cancer registry (PBCR) and the diagnosis of APL obtained through incident cases from a hospital-based cohort. The homozygous deletion in glutathione S-transferases (GSTs) leads to a loss of enzyme detoxification activity, possibly affecting the treatment response. Mutations in the RAS pathway genes are also considered to be a key component of the disease both in the pathogenesis and in the outcomes. We have assessed mutations in a RAS–MAP kinase pathway (FLT3, PTPN11, and K-/NRAS) and GST variant predisposition risk in the outcome. Out of the 805 children and adolescents with acute myeloid leukemia (AML) who are registered in the PBCR, 35 (4.3%) were APL cases. The age-adjusted incidence rate (AAIR) was 0.03 per 100,000 person-years. One-hundred and sixty-three patients with APL were studied out of 931 AML cases (17.5%) from a hospital-based cohort. Mutations in FLT3, KRAS, and NRAS accounted for 52.1% of the cases. Patients with APL presented a 5-year probability of the overall survival (OS) of 67.3 ± 5.8%. A GST-theta 1 (GSTT1) null genotype conferred adverse prognosis, with an estimated hazard ratio of 2.8, 95% confidence interval (CI) 1.2–6.9. We speculate that the GSTT1 polymorphism is associated with therapeutics and would allow better OS of patients with APL with a GSTT1 null genotype.

Non-Hodgkin Lymphoma Epidemiology in Children From 2 Socioeconomic Regions in Mexico: 20-Year Registry (1996-2015)

PURPOSE

We analyzed the epidemiologic characteristics of different types of non-Hodgkin Lymphoma (NHL), excluding Burkitt Lymphoma, in 2 Mexican regions with different socioeconomic status.

MATERIALS AND METHODS

In this surveillance study, we analyzed the incidence rates (cases per million children/year) of different types of NHL according to the ICCC3, registered in 1996-2015, from 2 different socioeconomic regions in Mexico: central and southern, with higher and lower status, respectively.

RESULTS

The principal NHL subgroups were precursor (IIb1), mature B cell (IIb2), mature T/NK cell, and no other specification (NOS; 42.3%, 15.8%, 14.1%, and 27.8%, respectively). In both regions, the overall incidence rates were similar (central=5.3, 95% confidence interval [CI], 4.6-6.1 vs. southern=6.3, 95% CI, 4.6-8.4); also, there were no differences by types (precursor cell LNH, 2.3 vs. 2.5; mature B cell, 0.9 vs. 0.8; mature T/NK cells, 0.8 vs. 0.8; and NOS, 1.4 vs. 2.3). In both regions, a decreasing trend was found (central= -0.17%, 95% CI, -0.03 to -0.3, P=0.04; southern= -0.32%, 95% CI, -0.07 to -0.57, P=0.02), with major reduction of NHL NOS from 1996 to 2000. In both regions, men predominated (2.1:1).

CONCLUSIONS

Socioeconomic status did not influence the incidence rates of NHL. In this study, we found a reduction of NHL NOS, possibly due to better typing.

RELINF: prospective epidemiological registry of lymphoid neoplasms in Spain. A project from the GELTAMO group

Lymphomas are a large, heterogeneous group of neoplasms with well-defined characteristics, and this heterogeneity highlights the importance of epidemiological data. Knowledge of local epidemiology is essential to optimise resources, design clinical trials, and identify minority entities. Given there are few published epidemiological data on lymphoma in Spain, the Spanish Lymphoma and Autologous Bone Marrow Transplant Group created the RELINF project. The aim of this project is to determine the frequencies and distribution of lymphoid neoplasms in Spain and to analyse survival. We developed an online platform for the prospective collection of data on newly diagnosed cases of lymphoma in Spain between January 2014 and July 2018; 11,400 patients were registered. Diffuse large B cell lymphoma (DLBCL) and follicular lymphoma (FL) were the most frequent lymphomas in our series. Marginal B cell lymphoma frequency was higher than that reported in other studies, representing more than 11% of mature B cell lymphomas. Peripheral T cell lymphoma not otherwise specified (PTCL-NOS) was the most common subtype of T cell lymphoma, and NK/T cell lymphomas were more frequent than expected (5.4% of total). Hodgkin's lymphoma accounted for 12% of lymphoproliferative syndromes. Overall survival was greater than 90% at 2 years for indolent B cell lymphomas, and approximately 60% for DLBCL, somewhat lower than that previously reported. Survival was poor for PTCL-NOS and angioimmunoblastic T cell lymphoma, as expected; however, it was somewhat better than that in other studies for anaplastic large cell anaplastic lymphoma kinase lymphomas. This is the first prospective registry to report the frequencies, distribution, and survival of lymphomas in Spain. The frequencies and survival data we report here are globally consistent with that reported in other Western countries. These updated frequencies and survival statistics are necessary for developing appropriate management strategies for neoplasias in the Spanish population.

Clinical and Epidemiological Characteristics of Burkitt Lymphomas in Pediatric Patients from Two Defined Socioeconomic Regions in Mexico

We analyzed clinical and epidemiological characteristics of Burkitt lymphoma (BL) in two defined socioeconomic regions in Mexico: high socioeconomic region (HSER; with two political jurisdictions) and low socioeconomic region (LSER; with three jurisdictions). Of the 63 cases registered in the Childhood Cancer Registry (1996-2013), 45 (71.4%) were from HSER and 18 (28.6%) from LSER. The incidence was higher in the LSER (3.1 vs. 1.4 cases per million children/year). The sporadic form and Stages III/IV predominated in both regions. Only one post-renal transplant (HSER) was found. The male/female ratio was higher in the LSER (5.0 vs. 1.4). The peak incidence was in the 1-4 age group for LSER, and in the 5-9 age group for HSER. This difference in the sporadic BL by socioeconomic regions may be related to different exposure factors.

Incidence of Childhood Hodgkin Lymphoma in Mexico by Histologic Subtypes and Socioeconomic Regions

BACKGROUND

Incidence rates of the histologic subtypes of Hodgkin lymphoma (HL) differed with socioeconomic conditions.

MATERIALS AND METHODS

HL cases from the Register of Childhood Cancer (below 15 y of age) for 2 socioeconomic regions were analyzed. Central region has a high socioeconomic index; and the southern region a low index. The incidence rates (cases per million children/year) were estimated according to histologic subtypes, age groups, sex, clinical stages, time to diagnosis, and overall survival by regions.

RESULTS

The overall incidence was greater in the south (6.8 vs. 4.6), principally due to higher incidence of mixed cellularity subtype (3.8 vs. 1.0). In the south, the highest incidence was found in the 5- to 9-year-old group (9.2), whereas in the central region it was found in the 10- to 14-year-old group (7.4). There was a delay of ∼3 weeks in the time to diagnosis (P=0.36) in the south, but no difference in the percentage of advanced stages, adjusted by histologic subtype (61%, III and IV). The overall survival was 71%, differences were identified only for mixed cellularity cases (center=89.2 vs. south=61.5%, P=0.03).

CONCLUSIONS

Incidences of HL subtypes differed in relation to socioeconomic conditions in Mexico. In the south, the incidence of mixed cellularity was higher and there was an earlier peak of presentation.

Global characteristics of childhood acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) comprises approximately 5-10% of childhood acute myeloid leukemia (AML) cases in the US. While variation in this percentage among other populations was noted previously, global patterns of childhood APL have not been thoroughly characterized. In this comprehensive review of childhood APL, we examined its geographic pattern and the potential contribution of environmental factors to observed variation. In 142 studies (spanning >60 countries) identified, variation was apparent-de novo APL represented from 2% (Switzerland) to >50% (Nicaragua) of childhood AML in different geographic regions. Because a limited number of previous studies addressed specific environmental exposures that potentially underlie childhood APL development, we gathered 28 childhood cases of therapy-related APL, which exemplified associations between prior exposures to chemotherapeutic drugs/radiation and APL diagnosis. Future population-based studies examining childhood APL patterns and the potential association with specific environmental exposures and other risk factors are needed.

The Prognostic Significance of HbF in Childhood Haematological Malignancies

The degree of increase in foetal haemoglobin (HbF) synthesis in haematological malignancies may be associated with the degree of malignancy. The aim of the present study was to quantify HbF levels in various childhood haematological malignancies and also, to ascertain its prognostic significance by comparing the results with the already established standard prognostic factors. Newly diagnosed cases of haematological malignancies in the paediatric age group were included in the study. HbF levels were estimated in each case of the study group along with HbF levels of control group comprising healthy children of same age group. The estimation was done by HPLC and Modified Betke's method. 50 cases of newly diagnosed haematological malignancies were studied out of which most of the cases were of acute lymphoblastic leukaemia (ALL) [n = 30(60 %)] followed by acute myeloid leukaemia (AML) [n = 8(16 %)], Hodgkin's lymphoma [n = 7(14%)], non-Hodgkin's lymphoma [n = 5(10 %)]. Raised HbF levels were found in 43.3 % cases of ALL (13/30) and 37.5 % cases of AML (3/8). No significant rise in HbF level was found in cases of lymphomas. There was correlation between raised HbF level and poor prognostic factors in cases of ALL but no such correlation was found in cases of AML. HbF levels are often elevated in childhood leukaemias as compared to childhood lymphomas. Thus, the concentration of HbF in acute childhood leukaemia may be considered as a prognostic factor.

Acute leukemia incidence and patient survival among children and adults in the United States, 2001-2007

Since 2001, the World Health Organization classification for hematopoietic and lymphoid neoplasms has provided a framework for defining acute leukemia (AL) subtypes, although few population-based studies have assessed incidence patterns and patient survival accordingly. We assessed AL incidence rates (IRs), IR ratios (IRRs), and relative survival in the United States (2001-2007) in one of the first population-based, comprehensive assessments. Most subtypes of acute myeloid leukemia (AML) and acute lymphoblastic leukemia/lymphoma (ALL/L) predominated among males, from twice higher incidence of T-cell ALL/L among males than among females (IRR = 2.20) to nearly equal IRs of acute promyelocytic leukemia (APL; IRR = 1.08). Compared with non-Hispanic whites, Hispanics had significantly higher incidence of B-cell ALL/L (IRR = 1.64) and APL (IRR = 1.28); blacks had lower IRs of nearly all AL subtypes. All ALL/L but only some AML subtypes were associated with a bimodal age pattern. Among AML subtypes, survival was highest for APL and AML with inv(16). B-cell ALL/L had more favorable survival than T-cell ALL/L among the young; the converse occurred at older ages. Limitations of cancer registry data must be acknowledged, but the distinct AL incidence and survival patterns based on the World Health Organization classification support biologic diversity that should facilitate etiologic discovery, prognostication, and treatment advances.