Lymphoma and lymphoid leukemia incidence in Florida children: ethnic and racial distribution

Epidemiology of childhood acute leukemias in marginalized populations of the central-south region of Mexico: results from a population-based registry

Introduction

Acute leukemias (AL) are the main types of cancer in children worldwide. In Mexico, they represent one of the main causes of death in children under 20 years of age. Most of the studies on the incidence of AL in Mexico have been developed in the urban context of Greater Mexico City and no previous studies have been conducted in the central-south of the country through a population-based study. The aim of the present work was to identify the general and specific incidence rates of pediatric AL in three states of the south-central region of Mexico considered as some of the marginalized populations of Mexico (Puebla, Tlaxcala, and Oaxaca).

Methods

A population-based study was conducted. Children aged less than 20 years, resident in these states, and newly diagnosed with AL in public/private hospitals during the period 2021-2022 were identified. Crude incidence rates (cIR), standardized incidence rates (ASIRw), and incidence rates by state subregions (ASIRsr) were calculated. Rates were calculated using the direct and indirect method and reported per million children under 20 years of age. In addition, specific rates were calculated by age group, sex, leukemia subtype, and immunophenotype.

Results

A total of 388 cases with AL were registered. In the three states, the ASIRw for AL was 51.5 cases per million (0-14 years); in Puebla, it was 53.2, Tlaxcala 54.7, and Oaxaca de 47.7. In the age group between 0-19 years, the ASIRw were 44.3, 46.4, 48.2, and 49.6, in Puebla, Tlaxcala, and Oaxaca, respectively. B-cell acute lymphoblastic leukemia was the most common subtype across the three states.

Conclusion

The incidence of childhood AL in the central-south region of Mexico is within the range of rates reported in other populations of Latin American origin. Two incidence peaks were identified for lymphoblastic and myeloid leukemias. In addition, differences in the incidence of the disease were observed among state subregions which could be attributed to social factors linked to the ethnic origin of the inhabitants. Nonetheless, this hypothesis requires further investigation.

Trends in Pediatric Cancer Care in Florida From 1981-2020: Changing Patterns in a Growing and Increasingly Diverse Population

Background The Florida Association of Pediatric Tumor Programs (FAPTP) has used the Statewide Patient Information Reporting System (SPIRS) since 1981 to track all new cases of pediatric cancer. We reviewed the last 40 years of data to see how pediatric cancer care has evolved. Methods We retrospectively analyzed SPIRS data from 1981 through 2020 in five-year increments, looking at numbers of new diagnoses, care delivery sites, and trial enrollment in Children's Oncology Group (COG) studies. Results From 1981-2020 Florida's population increased almost 88% while the pediatric population only grew 61%. New pediatric cancer diagnoses increased 326% to over 1,000 new cases/year. The percentage of patients treated at FAPTP centers grew from 30% to 57% with an annual percentage change (APC) of 10.3% (95% Confidence Interval [CI] of 0.6 to 20.9%). The rate of COG clinical trial enrollment decreased from 32% in 1981-1985 to 20% in 2016-2020, for an APC of 8.91% (95% CI of -13.3 to -4.3%). Conclusions The striking increase in pediatric cancer cases in Florida over the last 40 years was out of proportion to the population growth. More patients received care at FAPTP centers, but a lower percentage were enrolled on COG trials.

Pediatric Plasma Cell Neoplasms: A Population-Based Study

INTRODUCTION

Plasma cell neoplasms are exceptionally rare in the pediatric population; the demographic characteristics and the clinical outcomes of plasma cell neoplasms in this population are currently poorly understood. The aim of this study was to provide a comprehensive analysis of pediatric plasma cell neoplasms, based on the United-States Surveillance, Epidemiology, and End Results (SEER) program registries.

MATERIALS AND METHODS

All pediatric patients (aged less than 20 years) diagnosed with a malignant plasma cell neoplasm were retrieved from the SEER Program database (18 registries), collecting patient records between 2000 and 2018. The plasma cell neoplasm type, sex, age at diagnosis, year of diagnosis, race and origin, primary disease site, follow-up duration, and vital status at the last known contact were retrieved and analyzed.

RESULTS

The age-adjusted incidence rate of plasma cell neoplasms for 1,000,000 person-years was 0.06 for the pediatric population (compared with 90.6 for the adult population). The types of pediatric plasma cell neoplasms predominantly consisted of plasmacytomas, with 11 solitary extraosseous plasmacytoma (42.3%) and 7 solitary bone plasmacytoma (26.9%), while plasma cell myelomas represented only a minority of the neoplasms (8 patients; 30.8%). Most plasmacytomas were localized in the head and neck region. Hispanic patients represented 50% of the pediatric plasma cell neoplasm cases (but only 11.1% of adult cases, P < .01). Female-to-Male ratio was 1.36. Five-year overall survival rates were 88.2% (95% confidence interval [95% CI]: 74.2%-100%) for pediatric plasmacytoma and 36.5% (95% CI: 12.4%-100%) for pediatric plasma cell myeloma (P = .013).

CONCLUSION

This first population-based study of pediatric plasma cell neoplasms underlines the rarity of this entity and demonstrates its unique characteristics, including the significant predominance of plasmacytomas, of female patients, and of patients from hispanic origin, and the poor clinical outcomes of pediatric plasma cell myeloma patients.

Persistently high incidence rates of childhood acute leukemias from 2010 to 2017 in Mexico City: A population study from the MIGICCL

Introduction

Over the years, the Hispanic population living in the United States has consistently shown high incidence rates of childhood acute leukemias (AL). Similarly, high AL incidence was previously observed in Mexico City (MC). Here, we estimated the AL incidence rates among children under 15 years of age in MC during the period 2010-2017.

Methods

The Mexican Interinstitutional Group for the Identification of the Causes of Childhood Leukemia conducted a study gathering clinical and epidemiological information regarding children newly diagnosed with AL at public health institutions of MC. Crude age incidence rates (cAIR) were obtained. Age-standardized incidence rates worldwide (ASIRw) and by municipalities (ASIRm) were calculated by the direct and indirect methods, respectively. These were reported per million population <15 years of age; stratified by age group, sex, AL subtypes, immunophenotype and gene rearrangements.

Results

A total of 903 AL cases were registered. The ASIRw was 63.3 (cases per million) for AL, 53.1 for acute lymphoblastic leukemia (ALL), and 9.4 for acute myeloblastic leukemia. The highest cAIR for AL was observed in the age group between 1 and 4 years (male: 102.34 and female: 82.73). By immunophenotype, the ASIRw was 47.3 for B-cell and 3.7 for T-cell. The incidence did not show any significant trends during the study period. The ASIRm for ALL were 68.6, 66.6 and 62.8 at Iztacalco, Venustiano Carranza and Benito Juárez, respectively, whereas, other municipalities exhibited null values mainly for AML.

Conclusion

The ASIRw for childhood AL in MC is among the highest reported worldwide. We observed spatial heterogeneity of rates by municipalities. The elevated AL incidence observed in Mexican children may be explained by a combination of genetic background and exposure to environmental risk factors.

Primary Cutaneous B-Cell Lymphomas in Children and Adolescents: A SEER Population-Based Study

BACKGROUND

Although primary cutaneous B-cell lymphomas (PCBCL) comprise 25% of all cutaneous lymphomas, their incidence in the pediatric population is unknown, and the information on pediatric PCBCL has mostly been gathered from individual case reports or series from single centers.

PATIENTS AND METHODS

This was a population-based, retrospective cohort study of patients in 18 cancer registries in the United States diagnosed between 2000 to 2016 through the Surveillance, Epidemiology, and End Results (SEER) program. Age-adjusted incidence rates were calculated for PCBCL in pediatric (<20 years) and adult (≥20 years) populations. Demographic, clinical, and pathological characteristics of PCBCL were compared between the two groups.

RESULTS

A total of 48 pediatric and 5128 adult PCBCL cases were included. Median age at diagnosis was 16.5 years and 65 years in the two groups, respectively. The major histologic subtypes of pediatric cases were marginal zone lymphoma (77.1%), followed by diffuse large B-cell lymphoma (12.5%) and follicle center lymphoma (10.4%), which were equally distributed in adults. The age-adjusted pediatric PCBCL incidence rate (per 1,000,000 person-years) was 0.12 (95% CI 0.09-0.16). The incidence in the adult population was approximately 40-fold higher than the one observed in the pediatric group (IRR 41.4, 95% CI 31.2-56.2). All 48 pediatric cases were alive during a median follow-up time of 48 months.

CONCLUSIONS

Pediatric PCBCL is a very rare disease affecting mostly adolescents of both sexes. The major histologic subtype is marginal zone lymphoma, and the prognosis is favorable.

Space-time clustering of childhood leukemia in Colombia: a nationwide study

BACKGROUND

Leukemia is the most common cancer in childhood. The estimated incidence rate of childhood leukemia in Colombia is one of the highest in America and little is known about its spatial distribution.

PURPOSE

To explore the presence of space-time clustering of childhood leukemia in Colombia.

METHODS

We included children less than 15 years of age with confirmed diagnosis of acute leukemia reported to the national surveillance system for cancer between 2009 and 2017. Kulldorff's spatio-temporal scan statistics were used with municipality and year of diagnosis as units for spatial and temporal analysis.

RESULTS

There were 3846 cases of childhood leukemia between 2009 and 2017 with a specific mean incidence rate of 33 cases per million person-years in children aged 0-14 years. We identified five spatial clusters of childhood leukemia in different regions of the country and specific time clustering during the study period.

CONCLUSION

Childhood leukemia seems to cluster in space and time in some regions of Colombia suggesting a common etiologic factor or conditions to be studied.

2016 US lymphoid malignancy statistics by World Health Organization subtypes

Collectively, lymphoid neoplasms are the fourth most common cancer and the sixth leading cause of cancer death in the United States. The authors provide contemporary lymphoid neoplasm statistics by subtype based on the 2008 World Health Organization classifications, including the most current US incidence and survival data. Presented for the first time are estimates of the total numbers of US lymphoid neoplasm cases by subtype as well as a detailed evaluation of incidence and survival statistics. In 2016, 136,960 new lymphoid neoplasms are expected. Overall lymphoma incidence rates have declined in recent years, but trends vary by subtype. Precursor lymphoid neoplasm incidence rates increased from 2001 to 2012, particularly for B-cell neoplasms. Among the mature lymphoid neoplasms, the fastest increase was for plasma cell neoplasms. Rates also increased for mantle cell lymphoma (males), marginal zone lymphoma, hairy cell leukemia, and mycosis fungoides. Like incidence, survival for both mature T-cell lymphomas and mature B-cell lymphomas varied by subtype and by race. Patients with peripheral T-cell lymphomas had among the worst 5-year relative survival (36%-56%, depending on race/sex), while those with mycosis fungoides had among the best survival (79%-92%). For B-cell lymphomas, 5-year survival ranged from 83% to 91% for patients with marginal zone lymphoma and from 78% to 92% for those with hairy cell leukemia; but the rates were as low as 47% to 63% for patients with Burkitt lymphoma and 44% to 48% for those with plasma cell neoplasms. In general, black men had the lowest survival across lymphoid malignancy subtypes. These contemporary incidence and survival statistics are useful for developing management strategies for these cancers and can offer clues regarding their etiology. CA Cancer J Clin 2016;66:443-459. © 2016 American Cancer Society.

Childhood leukemia incidence in California: High and rising in the Hispanic population

BACKGROUND

High rates of childhood leukemia incidence have been reported in Latin America and among Hispanic children in the United States. California's large Hispanic population affords an important opportunity to perform a detailed analysis of the leukemia burden among Hispanic children.

METHODS

Leukemias diagnosed among non-Hispanic white (NHW), Hispanic, African American (AA), and Asian/Pacific Islander (API) children aged birth to 19 years between January 1, 1990 and December 31, 2012 were obtained from the California Cancer Registry (11,084 cases). Age-adjusted incidence rates, standardized rate ratios (SRRs), and secular trends in incidence (annual percent change [APC]) were analyzed by subtype, race/ethnicity, sex, and age.

RESULTS

Compared with NHW children, the incidence of acute lymphoblastic leukemia (ALL) was higher among Hispanic (SRR, 1.32) and lower among AA (SRR, 0.55) and API (SRR, 0.91) children. From 1990 to 2012, the incidence of ALL increased overall (APC, 1.1%) and among males (APC, 1.0%), females (APC, 1.3%), Hispanics (APC, 1.1%), AAs (APC, 1.9%), AA males (APC, 2.8%), API males (APC, 1.9%), and Hispanic females (APC, 1.5%). The incidence of ALL increased among Hispanic males aged 15 to 19 years (APC, 2.5%) and Hispanic females aged birth to 4 years and 15 to 19 years (APCs of 2.2% and 1.9%, respectively). The incidence of acute myeloid leukemia did not appear to differ among racial/ethnic groups. From 1990 to 2012, the overall incidence of acute myeloid leukemia remained stable but increased among Hispanics (APC, 1.2%), females (APC, 1.0%), Hispanic females (APC, 2.3%), and Hispanic females aged 15 to 19 years (APC, 3.4%).

CONCLUSIONS

Notable differences in the incidence of childhood leukemia were observed among 4 racial/ethnic groups in California. Factors that may contribute to these differences include differential exposure to carcinogens and/or genetic susceptibility. Cancer 2016. © 2016 American Cancer Society. Cancer 2016;122:2867-2875. © 2016 American Cancer Society.

Understanding disparities in leukemia: a national study

PURPOSE

Disparities in solid tumors have been well studied. However, disparities in hematologic malignancies have been relatively unexplored on population-based levels. The purpose of this study is to examine the relationship between race/ethnicity and acute leukemia mortality.

METHODS

All patients with acute leukemia [acute lymphoblastic leukemia (ALL) and acute myelogenous leukemia (AML)] were identified in the Surveillance Epidemiology and End Results database, 1999-2008. Kaplan-Meier curves were generated to reflect survival probabilities by race/ethnicity. Multivariable Cox proportional hazard models estimated hazard of mortality by race with adjustment for individual (age, gender, year of diagnosis) and select genetic factors.

RESULTS

A total of 39,002 patients with acute leukemia were included in the study. Overall, there was a mortality disparity in acute leukemia for blacks (HR 1.17, p < 0.0001) and Hispanics (HR 1.13, p < 0.0001) compared with non-Hispanic whites. In stratified analysis, disparities in ALL were greater than AML; blacks (HR[ALL]1.45, p < 0.0001; HR[AML]1.12, p < 0.0011); Hispanics (HR[ALL]1.46, p < 0.0001; HR[AML]1.06, p < 0.0001). Adjustment for individual patient and select genetic factors did not explain disparities.

CONCLUSIONS

Blacks and Hispanics suffer decreased survival in acute leukemia as compared to others. Further investigation is needed to understand the drivers of poor cancer outcomes in these populations.

Childhood acute leukemias are frequent in Mexico City: descriptive epidemiology

Background

Worldwide, acute leukemia is the most common type of childhood cancer. It is particularly common in the Hispanic populations residing in the United States, Costa Rica, and Mexico City. The objective of this study was to determine the incidence of acute leukemia in children who were diagnosed and treated in public hospitals in Mexico City.

Methods

Included in this study were those children, under 15 years of age and residents of Mexico City, who were diagnosed in 2006 and 2007 with leukemia, as determined by using the International Classification of Childhood Cancer. The average annual incidence rates (AAIR), and the standardized average annual incidence rates (SAAIR) per million children were calculated. We calculated crude, age- and sex-specific incidence rates and adjusted for age by the direct method with the world population as standard. We determined if there were a correlation between the incidence of acute leukemias in the various boroughs of Mexico City and either the number of agricultural hectares, the average number of persons per household, or the municipal human development index for Mexico (used as a reference of socio-economic level).

Results

Although a total of 610 new cases of leukemia were registered during 2006-2007, only 228 fit the criteria for inclusion in this study. The overall SAAIR was 57.6 per million children (95% CI, 46.9-68.3); acute lymphoblastic leukemia (ALL) was the most frequent type of leukemia, constituting 85.1% of the cases (SAAIR: 49.5 per million), followed by acute myeloblastic leukemia at 12.3% (SAAIR: 6.9 per million), and chronic myeloid leukemia at 1.7% (SAAIR: 0.9 per million). The 1-4 years age group had the highest SAAIR for ALL (77.7 per million). For cases of ALL, 73.2% had precursor B-cell immunophenotype (SAAIR: 35.8 per million) and 12.4% had T-cell immunophenotype (SAAIR 6.3 per million). The peak ages for ALL were 2-6 years and 8-10 years. More than half the children (58.8%) were classified as high risk. There was a positive correlation between the average number of persons per household and the incidence of the pre-B immunophenotype (Pearson's r, 0.789; P = 0.02).

Conclusions

The frequency of ALL in Mexico City is among the highest in the world, similar to those found for Hispanics in the United States and in Costa Rica.

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

The aim of this study was to estimate the incidence of leukaemias and lymphomas in children according to the International Classification of Childhood Cancer third edition (ICCC-3) in the population covered by the Girona, Valencia, and Zaragoza population-based cancer registries and compare it with the incidence rates in other European countries. All haematological malignancies (HMs) registered between 1993 and 2002 in children below 15 years of age were included in the study. Pathological and haematological diagnoses were reviewed, recoded according to International Classification of Diseases for Oncology-3 and reclassified on the basis of ICCC-3. Sex and age-adjusted incidence rates were calculated, using the world population as standard. Five hundred and seventy-one HMs were registered in the Girona, Valencia and Zaragoza Cancer Registries during the study period. According to ICCC-3, precursor cell leukaemias were the most frequent HMs in children and constituted 60% of all HMs (an age-adjusted incidence rate of 42.7 per million children-years). The second most frequent childhood HM was Hodgkin lymphoma (11.2% of all HMs), yielding an age-adjusted standardized incidence rate of 6.3 per million children-years. With regard to myeloid lineage, acute myeloid leukaemias were the most frequent with a rate of 7.9 per million children-years. The standardized incidence rates for lymphoid leukaemia (1.19) and Burkitt lymphoma (3.94) were statistically higher than the rates observed in Europe. Compared with European data, Spain has a high incidence of lymphoid leukaemias and lymphomas. In particular, a high incidence of Burkitt lymphoma was observed. The causes of this geographical variation are still unknown.

Childhood cancer in relation to parental race and ethnicity: a 5-state pooled analysis

BACKGROUND

Children of different racial/ethnic backgrounds have varying risks of cancer. However, to the authors' knowledge, few studies to date have examined cancer occurrence in children of mixed ancestry.

METHODS

This population-based case-control study examined cancer among children aged <15 years using linked cancer and birth registry data from 5 US states from 1978 through 2004. Data were available for 13,249 cancer cases and 36,996 controls selected from birth records. Parental race/ethnicity was determined from birth records. Logistic regression analysis was used to examine the association of cancer with different racial/ethnic groups.

RESULTS

Compared with whites, blacks had a 28% decreased risk of cancer (odds ratio [OR], 0.72; 95% confidence interval [95% CI], 0.65-0.80), whereas both Asians and Hispanics had an approximate 15% decrease. Children of mixed white/black ancestry also were found to be at decreased risk (OR, 0.71; 95% CI, 0.56-0.90), but estimates for mixed white/Asian and white/Hispanic children did not differ from those of whites. Compared with whites: 1) black and mixed white/black children had decreased ORs for acute lymphoblastic leukemia (OR, 0.39 [95% CI, 0.31-0.49] and OR, 0.58 [95% CI, 0.37-0.91], respectively); 2) Asian and mixed white/Asian children had decreased ORs for brain tumors (OR, 0.51 [95% CI, 0.39-0.68] and OR, 0.79 [95% CI, 0.54-1.16], respectively); and 3) Hispanic and mixed white/Hispanic children had decreased ORs for neuroblastoma (OR, 0.51 [95% CI, 0.42-0.61] and OR, 0.67 [95% CI, 0.50-0.90], respectively).

CONCLUSIONS

Children of mixed ancestry tend to have disease risks that are more similar to those of racial/ethnic minority children than the white majority group. This tendency may help formulate etiologic studies designed to study possible genetic and environmental differences more directly.

Genetic rearrangement MLL/AF4 is most frequent in children with acute lymphoblastic leukemias in Mexico City

One of the highest incidences of acute lymphoblastic leukemia (ALL) in the world has been reported in Mexico City. In the current study (26 cases), the frequencies of the most frequent genetic rearrangements TEL-AML1, MLL/AF4, BCR-ABL (major and minor) in ALL in children from Mexico City were determined. For the ALL, the frequency of MLL/AF4 was 65.4%, for TEL-AML1 and that of BCR/ABL was 3.8%. Only 6 of the 17 children with the MLL/AF4 rearrangement were less than 26 months old. The frequency reported for MLL/AF4 in Mexican children with ALL is one of the highest worldwide. These findings could potentially explain the higher frequency of ALL with poor prognosis for children in Mexico City.

Patterns of leukemia incidence in the United States by subtype and demographic characteristics, 1997-2002

OBJECTIVE

Efforts to prevent leukemia have been hampered by an inability to identify significant risk factors. Exploring incidence patterns of leukemia subtypes by sex and race/ethnic group may generate new etiologic hypotheses and identify high-risk groups for further study.

METHODS

Data from the North American Association of Central Cancer Registries for 1997-2002 were used to assess patterns of leukemia incidence by subtype, sex, age, race and ethnicity.

RESULTS

A total of 144,559 leukemia cases were identified, including 66,067 (46%) acute and 71,860 (50%) chronic leukemias. The highest rates of acute myeloid leukemia with and without maturation were observed in Asian-Pacific Islanders (API). Hispanics had a higher incidence of acute lymphocytic leukemia, particularly in childhood, and promyelocytic leukemia than did non-Hispanics. African-Americans had the highest rates of HTLV-1 positive adult T-cell leukemia/lymphoma. A sharp increase in the incidence of chronic myeloid leukemia was observed for both APIs and Hispanics, 85 years and older.

CONCLUSION

Known risk factors are unlikely to explain the observed disparities in leukemia incidence. Further studies of differences in environmental and genetic risk factors in these populations by specific leukemia subtype may provide clues to the etiologies of these malignancies.

Phase I and Phase II Enzyme Polymorphisms and Childhood Cancer

Childhood cancers continue to be challenging clinical entities whose etiology, demographic characteristics, clinical progression, treatment efficacy, and outcomes remain incompletely understood. Research suggests that multiple environmental and genetic factors may play crucial roles in the pathophysiology of many of these malignancies. Recent attention has been directed to the role of carcinogen metabolizing enzymes in the etiology and progression of cancer in both adults and children due to their multitude of polymorphic variants and their intimate interaction with environmental factors. In particular, xenobiotic metabolizing enzymes (XME), which are intimately involved in the activation and deactivation of many environmental carcinogens, have become an area of significant interest. Traditionally, these enzymes have been classified into either phase I or phase II enzymes depending on their substrates, activity, and occasionally based on their sequence in the metabolic pathways, and have been demonstrated to have numerous polymorphic variants. Phase I enzymes predominantly consist of cytochrome enzymes responsible for mixed function oxidase activity, whereas phase II enzymes are frequently conjugation reactions necessary for drug metabolism or the further metabolism of phase I enzyme products. Current research has discovered numerous interactions between polymorphisms in these enzymes and changes in cancer susceptibility, treatment efficacy, and clinical outcomes in childhood cancer. Furthermore, studies of polymorphisms in these enzymes have demonstrated to have synergistic/antagonistic interactions with other XME polymorphisms and demonstrate variable influences on disease pathophysiology depending on the patient's ethnic background and environmental milieu. Continuing research on the role of polymorphisms in phase I and phase II enzymes will likely further elucidate the intimate role of these polymorphisms with environmental factors in the etiology of childhood cancer.

Improved outcome in South African children of mixed ethnicity treated for all

A historical cohort study with an analytical component was conducted to determine whether risk-appropriate chemotherapy can improve survival in children of mixed ethnicity with ALL. Eighty-one coloured children treated for ALL in South Africa were divided into 2 groups: group A (n = 39), treated prior to 1992, and group B (n = 42), treated after 1992. A comparison was made of survival, treatment complications, and supportive measures. The two groups were comparable. The mean nadirs of the white cell count (p < .01), platelet count (p = .01), and hemoglobin value (p < .01) were significantly lower in group B. The survival rate of 37% in group A improved to 66% in group B (p = .025). The results show that a risk-adapted regimen increased survival in children of mixed ethnicity in the Western Cape, despite increased hematological toxicity and episodes of febrile neutropenia.

Incidence of leukemias in children from El Salvador and Mexico City between 1996 and 2000: population-based data

BACKGROUND

There are very few studies that report the incidence of acute leukemias in children in Latin America. This work assesses the incidence of acute leukemias, between 1996 and 2000, in children from 0-14 years old who were attended at the Mexican Social Security Institute in Mexico City and in children from 0-11 years old in El Salvador.

METHODS

DESIGN

Population-based data. Hospitals: In San Salvador, El Salvador, Hospital Nacional de Niños "Benjamin Bloom", the only center in El Salvador which attends all children, younger than 12 years, with oncologic disease. The Pediatric Hospital and the General Hospital of the Mexican Social Security Institute in Mexico City, the only centers in Mexico City which attend all those children with acute leukemia who have a right to this service.

DIAGNOSIS

All patients were diagnosed by bone marrow smear and were divided into acute lymphoid leukemia (ALL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and unspecified leukemias (UL). The annual incidence rate (AIR) and average annual incidence rate (AAIR) were calculated per million children. Cases were stratified by age and assigned to one of four age strata: 1) <1 year; 2) 1-4 years; 3) 5-9 years, or 4) 10-14 or 10-11 years, for Mexico City and El Salvador, respectively.

RESULTS

The number of cases was 375 and 238 in El Salvador and Mexico City, respectively. AAIRs in Mexico City were 44.9, 10.6, 2.5, 0.5, and 58.4 per million children for ALL, AML, CML, UL, and total leukemias, respectively. The AAIRs in El Salvador could not be calculated because the fourth age stratum in El Salvador included children only from 0-11 years old. The incidence rates for the Salvadorian group of 0-11 year olds were 34.2, 7.1, 0.6, 0.2, and 43.2 per million children for ALL, AML, CML, UL, and total leukemias, respectively.

CONCLUSION

Reported AIRs for each age group in El Salvador were similar to those from other American countries. The AAIR of ALL in Mexico City is one of the highest reported for North America.

Epidemiology and genetics of childhood cancer

Childhood cancer is rare everywhere in the world, with age-standardized annual incidence usually between 70 and 160 per million at age 0-14 years. Greater variation is seen between populations for some specific tumour types. Some of the largest variations are geographical and are attributable to environmental factors, whereas variation mainly on ethnic lines seems likely to be a marker of genetic predisposition. A wide range of familial and genetic syndromes is associated with an increased risk of childhood cancer. Virtually all the excess risk of cancer among first-degree relatives of children with cancer can be accounted for by known hereditary syndromes. Studies of weak predisposition and gene-environment interaction have so far shown limited consistency. There are very few established environmental or exogenous risk factors and most of these are infective agents. Many putative risk factors can hardly ever be investigated epidemiologically except by interview or questionnaire studies. Some recent examples illustrate the continuing problems of participation bias and recall bias.

Pattern of Epstein-Barr virus association in childhood non-Hodgkin's lymphoma: Experience of University of Malaya Medical Center

The pattern of childhood non-Hodgkin's lymphoma (NHL) usually differs in adults. The most common subtypes are lymphoblastic, Burkitt's and anaplastic large cell lymphoma. Recent data indicate that a higher risk of developing lymphoma is associated in children of certain ethnic origins. The difference is probably related to the underlying etiological factors of these diseases, and Epstein-Barr virus (EBV) is a strong candidate. The present study aims to determine the disease pattern of childhood lymphomas in the University Hospital Kuala Lumpur, for a direct comparison to the reported data of adults from the same medical center. A total of 69 and 34 childhood NHL and Hodgkin's lymphomas, respectively, were retrieved. The most common subtypes were lymphoblastic (23 cases), Burkitt's (25 cases) and anaplastic large cell lymphomas (9 cases). Epstein-Barr virus association was more prevalent in B-cell (23%) than T-cell (12%) lymphomas. The most common EBV-associated tumor was Burkitt's lymphoma, and there was an increased risk of EBV association for Burkitt's lymphoma in Chinese patients. In conclusion, the pattern of childhood lymphoma in Malaysia is relatively similar to children elsewhere in the world. The EBV association of B- and T-NHL differs between children and adults from the same medical center because of differences in the subtype composition in these two age groups.