Incidence of childhood cancer in Latin America and the Caribbean: coverage, patterns, and time trends / Incidencia del cáncer infantil en América Latina y el Caribe: cobertura de los registros, patrones y tendencias a lo largo del tiempo / Incidência de câncer infantil na América Latina e no Caribe: cobertura, padrões e tendências temporais

ABSTRACT Objective. To provide a comprehensive overview of geographical patterns (2001-2010) and time trends (1993-2012) of cancer incidence in children aged 0-19 years in Latin America and the Caribbean (LAC) and interpret the findings in the context of global patterns. Methods. Geographical variations in 2001-2010 and incidence trends over 1993-2012 in the population of LAC younger than 20 years were described using the database of the third volume of the International Incidence of Childhood Cancer study containing comparable data. Age-specific incidence per million person-years (ASR) was calculated for population subgroups and age-standardized (WSR) using the world standard population. Results. Overall, 36 744 unique cases were included in this study. In 2001-2010 the overall WSR in age 0-14 years was 132.6. The most frequent were leukemia (WSR 48.7), central nervous system neoplasms (WSR 23.0), and lymphoma (WSR 16.6). The overall ASR in age group 15-19 years was 152.3 with lymphoma ranking first (ASR 30.2). Incidence was higher in males than in females, and higher in South America than in Central America and the Caribbean. Compared with global data LAC incidence was lower overall, except for leukemia and lymphoma at age 0-14 years and the other and unspecified tumors at any age. Overall incidence at age 0-19 years increased by 1.0% per year (95% CI [0.6, 1.3]) over 1993-2012. The included registries covered 16% of population aged 0-14 years and 10% of population aged 15-19 years. Conclusions. The observed patterns provide a baseline to assess the status and evolution of childhood cancer occurrence in the region. Extended and sustained support of cancer registration is required to improve representativeness and timeliness of data for childhood cancer control in LAC.

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RESUMO Objetivo. Apresentar uma visão abrangente dos padrões geográficos (2001 a 2010) e das tendências temporais (1993 a 2012) da incidência de câncer em crianças e jovens de 0 a 19 anos na América Latina e no Caribe (ALC) e interpretar os resultados no contexto de padrões mundiais. Métodos. Foram descritas variações geográficas de 2001 a 2010 e tendências de incidência de 1993 a 2012 na população com menos de 20 anos da ALC usando informações comparáveis da base de dados do terceiro volume do estudo International Incidence of Childhood Cancer. Foram calculadas taxas de incidência específica por idade por milhão de pessoas-ano (ASR, na sigla em inglês) para subgrupos populacionais e taxas padronizadas por idade usando a população padrão mundial (WSR, na sigla em inglês). Resultados. No total, foram incluídos 36 744 casos únicos. No período de 2001 a 2010, a WSR para todos os tumores combinados na faixa etária de 0 a 14 anos foi de 132,6. Os diagnósticos mais frequentes foram leucemia (WSR de 48,7), neoplasias do sistema nervoso central (WSR de 23,0) e linfoma (WSR de 16,6). A ASR para todos os tumores combinados na faixa etária de 15 a 19 anos foi de 152,3, e a maior taxa foi a de linfoma (ASR de 30,2). A incidência foi maior no sexo masculino do que no sexo feminino e maior na América do Sul do que na América Central e no Caribe. De modo geral, em comparação com as estimativas mundiais, a incidência na ALC foi menor, exceto para leucemia e linfoma entre 0 e 14 anos e para outros tumores e tumores não especificados em qualquer idade. A taxa de incidência na faixa etária de 0 a 19 anos aumentou em 1,0% ao ano (IC de 95% [0,6, 1,3]) entre 1993 e 2012. Os registros incluídos cobriam 16% da população de 0 a 14 anos e 10% da população de 15 a 19 anos. Conclusões. Os padrões observados servem de referência para avaliar o status e a evolução da ocorrência de câncer infantil na região. É necessário garantir um apoio ampliado e consistente aos registros de câncer para aprimorar a representatividade e a disponibilidade das informações em tempo adequado para o controle do câncer infantil na ALC.

EBV, HCMV, HHV6, and HHV7 screening in bone marrow samples from children with acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is the most common cancer in childhood worldwide and Mexico has reported one of the highest incidence rates. An infectious etiology has been suggested and supported by epidemiological evidences; however, the identity of the involved agent(s) is not known. We considered that early transmitted lymphotropic herpes viruses were good candidates, since transforming mechanisms have been described for them and some are already associated with human cancers. In this study we interrogated the direct role of EBV, HCMV, HHV6, and HHV7 human herpes viruses in childhood ALL. Viral genomes were screened in 70 bone marrow samples from ALL patients through standard and a more sensitive nested PCR. Positive samples were detected only by nested PCR indicating a low level of infection. Our result argues that viral genomes were not present in all leukemic cells, and, hence, infection most likely was not part of the initial genetic lesions leading to ALL. The high statistical power of the study suggested that these agents are not involved in the genesis of ALL in Mexican children. Additional analysis showed that detected infections or coinfections were not associated with prognosis.

Allergy and acute leukaemia in children with Down syndrome: a population study. Report from the Mexican inter-institutional group for the identification of the causes of childhood leukaemia.

BACKGROUND: Allergies have been described as protective factors against the development of childhood acute leukaemia (AL). Our objective was to investigate the associations between allergy history and the development of AL and acute lymphoblastic leukaemia (ALL) in children with Down syndrome (DS). METHODS: A case-control study was performed in Mexico City. The cases (n=97) were diagnosed at nine public hospitals, and the controls (n=222) were recruited at institutions for children with DS. Odds ratios (OR) were calculated. RESULTS: Asthma was positively associated with AL development (OR=4.18; 95% confidence interval (CI): 1.47-11.87), whereas skin allergies were negatively associated (OR=0.42; 95% CI: 0.20-0.91). CONCLUSION: Our findings suggest that allergies and AL in children with DS share biological and immune mechanisms. To our knowledge, this is the first study reporting associations between allergies and AL in children with DS.

Breastfeeding and early infection in the aetiology of childhood leukaemia in Down syndrome.

BACKGROUND: For a child to develop acute leukaemia (AL), environmental exposure may not be sufficient: interaction with a susceptibility factor to the disease, such as Down syndrome (DS), may also be necessary. We assessed whether breastfeeding and early infection were associated with the risk of developing AL in children with DS. METHODS: Children with DS in Mexico City, and either with or without AL, were the cases (N=57) and controls (N=218), respectively. Population was divided in children with AL and with acute lymphoblastic leukaemia (ALL) and also in children < or = 6 and >6 years old. RESULTS: Breastfeeding and early infections showed moderate (but not significant) association for AL, whereas hospitalisation by infection during the first year of life increased the risk: odds ratios (confidence interval 95%) were 0.84 (0.43-1.61), 1.70 (0.82-3.52); and 3.57 (1.59-8.05), respectively. A similar result was obtained when only ALL was analysed. CONCLUSION: We found that breastfeeding was a protective factor for developing AL and ALL, and during the first year of life, infections requiring hospitalisation were related to a risk for developing the disease in those children with DS >6 years of age. These data do not support the Greaves's hypothesis of early infection being protective for developing ALL.

Epidemiology of cancer in children under one year of age in Mexico City.

In this work, the epidemiology of cancer in children under one year of age in Mexico City is described. A survey (observational, descriptive and prolective study) from 1 January 1996 to 31 December 1999 was conducted at two paediatric hospitals of the Instituto Mexicano de Seguro Social in Mexico City (IMSS-MC). To calculate both the general and the by sex incidence (rates are given per 10) all new cases recorded for children under one year of age (numerator) and Mexico City population served by the IMSS (denominator) were used. When the total of 34 cases that fulfilled the requirements was analysed, an incidence of 194.5 was obtained. Leukaemia occupied first place with a rate of 68.6 and hepatic and germinal cells tumours occupied second place with an incidence of 28.6, whereas peripheral nervous system tumours (neuroblastoma) showed a very low rate (11.4). Overall, the male/female ratio for tumours was 1.4:1, with the ratio varying with different types of tumours. Cancer incidence in this population was shown to be close to that in developed countries, but differed in the distribution of the type of tumour: leukaemia had a very high incidence and that for neuroblastoma was very low.

[Factors that influence non-donation of blood in relatives of patients at a pediatric hospital]. / Factores que influyen en la no-donación de sangre en los familiares de pacientes de un hospital pediátrico.

OBJECTIVE: To identify factors that influence refusing to donating blood. MATERIAL AND METHODS: Prospective case and control study. Hospitalized patients' relatives were interviewed with a questionnaire to evaluate their knowledge of blood and personal attitudes toward blood donation. Cases were all relatives who did not donate blood and controls who did. RESULTS: A total of 121 individuals was studied, 30 cases and 91 controls. Age of the cases was 32.3 +/- 8.1 years and controls was 28.8 +/- 7.9 years (p = 0.04). Risk factors were female sex (OR = 6.3; 95%CI 2.4 to 17.1), being married (OR = 3.7 95%CI 1.3 to 10.5). No differences were present between the two groups in level of knowledge concerning blood. The average of positive attitudes toward blood donation was greater among relatives who donated blood (cases 5.9 +/- 1.6; controls 6.4 +/- 1.2; P = 0.049). Among the attitudes that influence refusing to donate blood were fear of getting dizzy at the sight of blood (OR = 5.2, 95%CI 1.3-21.4), fear of donating blood (OR = 2.2, 95%C, 0.8-6.0), and getting nervous at the sight of blood (OR = 4.1, 95%CI% 1.5-10.9). CONCLUSIONS: Among patient's relatives who donate blood positive personal attitudes toward blood donation have more weight than knowledge on the subject.

[Incidence of acute leukemia in children in Mexico City, from 1982 to 1991]. / Incidencia de las leucemias agudas en niños de la ciudad de México, de 1982 a 1991.

OBJECTIVE: To measure the incidence rate and trend of acute leukemia (AL) in political districts of Mexico City. MATERIAL AND METHODS: Descriptive longitudinal study conducted at six hospitals that care for nearly 97.5% of all cancer cases among children in Mexico City. Study data were collected in 1995 and 1996, and were analyzed in 1999, at the National Medical Center "Siglo XXI" Children's Hospital, of the Mexican Institute for Social Security. Calculations of acute leukemia annual incidence rates, standardized rates, and standardized morbidity rates (SMR) with 95% confidence intervals, were obtained for each district. Morbidity trends were assessed through average change rates. RESULTS: In this study we observed an increasing trend of acute lymphoblastic leukemia (ALL) incidence in five districts: Alvaro Obregon, Cuauhtemoc, Gustavo A. Madero, Iztacalco, and Venustiano Carranza. Acute myeloblastic leukemia (AML) showed no significantly statistic increase of incidence in any district. AML did show a significant SMR in Alvaro Obregon district (SMR = 2.91, 95% CI 1.63-4.80). Higher SMRs were found in the south and southwest areas of the city. CONCLUSIONS: Increasing incidence of ALL was observed in five districts of Mexico City. AML incidence was the highest in Alvaro Obregon district.

Validation of a prognostic index in the critically ill newborn.

OBJECTIVE: Elaborate and assess the degree of validity of a prognostic model for evaluating patients admitted to the Neonatal Intensive Care Unit (NICU). DESIGN: Cases and controls nested in a cohort. SETTING: NICU of two tertiary hospitals and another second level hospital. PATIENTS: The study was carried out in two phases. During the first phase (elaboration of a model), 336 newborns were studied; 112 belonged to the case group (dead patients) and 224 to the control group (live patients discharged). For the second phase (model validation), 300 patients were included that did not participate in the first phase, 100 cases and 200 controls. MEASUREMENTS: For each patient admitted to the study, clinical, paraclinical, perinatal and comorbidity factors were determined within the first 12 hours. Variables of statistical significance in the bivariate analysis were included in a logistic regression model with the objective of identifying a prognostic model. RESULTS: The variables that constituted the prognostic index were gestational age x birth weight, the paO2/FiO2 ratio x O2 saturation, arrest cardiac, major congenital malformations, septicemia and base excess. The model showed to have a sensitivity of 70% and a specificity of 91% during the elaboration cohort. In the validation cohort, sensitivity was 68% and specificity was 92%, a positive predictive value of 80%, negative predictive value of 85% and a correct classification rate was 84%. CONCLUSIONS: The Neonatal Mortality Prognostic Index (NMPI) developed in this study showed to be useful for the evaluation of hospital mortality for severely ill newborns admitted to NICU.

[Cryptosporidium parvum infection in malnourished and non malnourished children without diarrhea in a Mexican rural population]. / Infección por Cryptosporidium parvum en niños desnutridos y no desnutridos sin diarrea en una población rural mexicana.

UNLABELLED: Cryptosporidium parvum is associated with diarrheic disease and mainly affects children and immunocompromised hosts. In most of the cases, cryptosporidiosis infection is asymptomatic in immunocompetent subjects. The objectives of the study were to determine the frequency of asymptomatic infection caused by the parasite in children with and without malnutrition and to determine the risk factors associated to infection. METHODS: Children from one to fifteen years old without diarrhea were included, somatometry were performed. The socioeconomic and sanitary conditions were investigated for each family and community. The Faust method and Kinyoun stain were employed identify parasites and Cryptosporidium parvum in feces. Odds ratio (OR), 95% confidence intervals (75% CI), chi 2 Mantel-Haenszel, Fisher exact test and chi 2 trends were calculated. RESULTS: One hundred thirty two children were included. In 10/132 (7.5%) cysts of Cryptosporidium were found, 7/71 in children with malnutrition (9.8%) and 3/61 without malnutrition (4.9%) p = 0.23. 69.7% of the children had parasitosis. According to the presence of C. parvum in feces, the different factors calculated were: Diarrhea in family OR = 5.82 (95%IC 0.86-39.18), not hand washing OR = 5.08 (95%IC 0.62-110.49), age less than 5 years old OR = 4.90 (95%IC 0.60-106.9), drinking non-potable water OR = 3.34 (95%IC 0.40-73.01) and malnutrition 2.11 (95%IC 0.46-10.89). Association was found between the number of people in the same house and the risk of infection (p = 0.005). The presence of diarrhea in the family (OR = 4.15, 95%IC 0.47-36.91) and drinking non-potable water (OR = 4.19, 95%IC 0.48-36.32) were the significant factors in the regression logistic model. CONCLUSIONS: The frequency of Cryptosporidium infection were 7.5%. Diarrhea in the family, overcrowding and drinking non-potable water were associated with C. parvum infection, malnutrition was not a significant risk factor.

[Descriptive epidemiology of malignant tumors in children]. / Epidemiología descriptiva de las neoplasias malignas en niños.

The object of this study is to present the descriptive epidemiology of cancer in children at the world and national levels. The international and national literature published on cancer in children was comprehensively reviewed, with emphasis on reports treating epidemiological aspects of time, place and person. For practical reasons and with the aim of integrating the information, only the more relevant publications were included. Incidence and child mortality were analyzed. Overall incidence is between 100 and 150 (annual rates = cases x 10(6) children). Specific incidence varies according to the type of cancer, the region and the country. The Latin American pattern of neoplasms is constituted by leukemias, lymphomas, and central nervous system tumors (CNST); in the Northamerican/European pattern the CNST appear in second place and in the African pattern, lymphomas show predominance. Incidence is higher among the younger than 5 year olds, from urban environments, and there is a 1% annual increase of cancer in Northamerican children. Child mortality has diminished remarkably, mainly in developed countries, whereas in developing or underdeveloped countries, incidence remains stable or shows a slight fall. The incidence of cancer in children is greater in developed countries, but in underdeveloped countries it may be underestimated. These countries have not managed to reduce the incidence of child mortality caused by cancer, as have the United States or Great Britain. Further studies on the epidemiology of cancer in children are necessary, since many data remain unknown.

[The trend in pregnancies terminated by a cesarean operation in Mexico during 1991-1995]. / Tendencia de los embarazos terminados por operación cesárea en México durante el periodo 1991-1995.

In the last decades has been a worldwide trend to increase the number of cesarean sections as an alternative of obstetric resolution, phenomenon for which it was proposed a variety of explanation, this fact remains practically unknown in the institutions of the National Health System (NHS) in Mexico. To identify the trend of the pregnancy to end for cesarean sections during the years of 1991-1995 in the 32 states of de country, as well as of all the institutions of the National Health System. Descriptive, cross sectional and retrospective. We use the data of the Bureau of Statistics and Informatics of de Health Ministry of each one of the 32 states of the country, of the years 1991 to 1995, and of the number of cesarean sections made in the hospitals of the different institutions of the NHS. We started off with a data-base, to calculate frequency tables, and the specific rate of the cesarean section for each year, for each one of the states and institutions of the NHS. We calculate the secular trends using the annual rates of cesarean section, for each one of the states and institutions of the NHS. We also made bivariate analysis and estimated the odds ratio (OR) and 95% Confidence Interval (95% IC); and the statistic X2 for trend, setting the two tailed statistic significance level of 0.05. During the study period, there was 7,503,817 births in all hospitals of the NHS, of these births 1,929,865 (25.72%) was resolved by cesarean section. For the whole period it there was a clear trend to increment of the cesarean section, the rate for 1991 was 20.44%, and by 1995 was 28.58%, the raise for the period was 39.82%, with values of the OR for trend of 1.56; 95% IC (1.55-1.57). "P" < 0.05. The rate for institutions attending open population had an increment of 35.08% [OR trend 1.45; 95% IC (1.43-1.46), "p" < 0.05], of them the highest rate was for the State System of Health in 1995 with 29.78%, the rates for the remaining institutions varied from 16.57% for the IMSS/SOLIDARIDAD and 21.7% for the Health Ministry, all trends were statistically significant. In relation to the institutes attending closed population the raise was of 53.27% [OR trend 1.82; 95% IC (1.81-1.83), "p" < 0.05], with the highest rate for the National Defense Ministry which had a rate of 51-15%, the rates for the remaining institutions varied from 33.52% for the Mexican Institute of Social Security (IMSS) to 43.89% for the Institute of Safety and Social Services for the State Workers (ISSSTE), with exception of the Management of the Medical Services of the Mexican Oils (PEMEX) and the Marine Ministry (SECMAR), all trends were statistically significant. When the analysis of the cesarean section rates for the 32 states of the Mexican Republic was carried out, we found that in 1995, the national average rate was 28.58%, the lowest rate corresponded to the state of Zacatecas with 19.82% and the highest to the state of Nuevo León with 42.14%. There was a tendency to increment for all states which varied from 23.55% for the state Chiapas and 67.97% for the states of Querétaro, all increments were statistically significant. We conclude, that rates of cesarean section for both, institutions of NHS and states of the Mexican Republic, are of the highest in the world, no matter what big the interinstitutional and interstate variation are. The highest rates occurred in institutions attending closed population, and the states with a higher degree of socioeconomic development.

Malnutrition in childhood lymphoblastic leukemia: a predictor of early mortality during the induction-to-remission phase of the treatment.

BACKGROUND: Previous reports have shown that undernourished children with acute lymphoblastic leukemia (ALL) have a poorer long-term survival as compared with children with normal nourishment status. It has been shown that both the relapse and mortality rates of undernourished children with ALL are higher during the continuation phase of the chemotherapy and are apparently related to a poor tolerance of ablative chemotherapy. No previous articles have analyzed the early mortality rate of these patients. METHODS: We carried out a case-control study, and have studied the effect of severe malnutrition on the mortality of 17 children with ALL during the initial induction-to-remission phase of the treatment. These 17 cases were compared with 76 controls who had survived at least the phases of induction and consolidation. RESULTS: It was found that the chance of dying during the initial phase of the treatment was 2.6 times higher (confidence interval 95%: 0.55-11.89) in undernourished children with ALL than in those children with normal nourishment status. The risk of death increased with the severity of undernourishment (p = 0.04). CONCLUSIONS: These data confirm the prognostic value of malnutrition in children with ALL and suggest that undernourishment may also influence early mortality during the induction-to-remission phase of the treatment.

[Risk factors for the development of germ cell tumors in children]. / Factores de riesgo para el desarrollo de tumores de células germinales en niños.

The search for risk factors for development of germ cell tumors (GCT) in children who lived in Mexico City (MC). A protective, observational, case-control study was conducted in children under 15 years of age resident in MC, insurer by the Mexican Institute of Social Security. The study population was selected between January 1st, 1990 and December 31st, 1994. Parents of the children were interviewed with a 230-items precoded questionnaire, validated previously with a pilot study. For analysis were obtained simple frequencies and odds ratios (OR) and 95% confidence interval (95%CI). There were 21 cases and 105 controls. The most significant risk factors were winter conception (OR = 7.6, 95% CI 1.5-39.3; P = 0.007); low parental education level (OR = 2.9, 95% CI 1.1-7.5; P = 0.026); and parental combined dust and electricity exposure before pregnancy (OR = 26, 95% CI 2.28-1291.86; P = 0.0007). during (OR8.58, 95% CI 0.89-106.55; P = 0.041) and after pregnancy (OR = 9.66, 95% CI 0.99-120.22; P = 0.027). There was a protective effect with repetitive infections during infancy. In conclusion, Winter conception is in accordance with infectious etiology theory of GCT development. The low parental education level and the combined exposure to dust and electricity are very important. The protective effect of repetitive infections and other factors make necessary more epidemiologic studies in this field.

[Classification by levels of clinico-epidemiological research designs]. / Clasificación en niveles de los diseños de investigación clínico-epidemiológicos.

The objective was to identify the characteristics of epidemiologic designs enabling their classification. A critical review of the literature in the clinical epidemiologic area was done to establish the main differences between designs. A meeting with experts to discuss this controversial topic and obtain criteria by consensus was organized. We propose an integral classification based on levels with two fundamental shafts: intervention and explanatory reasoning.

Epidemiology of lymphomas in children residing in Mexico City.

BACKGROUND: The aim of this paper is to present the epidemiological characteristics of time, subject and place of lymphomas in children residing in Mexico City, Mexico (MC). METHODS: The type of study was a retrospective hospital survey. All records of children with lymphomas registered between 1982 and 1991 at the main hospitals that treat children with cancer in MC were reviewed. Neoplasms were classified into Hodgkin's disease (HD) and non-Hodgkin's lymphomas (NonHL). Trend and incidence by sex, age and area of residence in MC were evaluated. Time of diagnosis, as well as parental occupation and educational level, were registered. RESULTS: A trend was only observed for HD in the total group (r:0.62; P = 0.05). In 1991, incidence for HD was 6.12 (rates x 10(6)) and 3.87 for NonHL. The highest average incidence was found in children 5-9 years of age (5.40) for HD, and in the age groups of 1-4 and 5-9 (3.10 and 3.33, respectively), for NonHL. Incidence was higher among boys for both lymphoma categories, but the male-to-female ratio was much higher in HD. Time of diagnosis, incidence in terms of place of residence, and parental educational level and occupation also differed from one lymphoma category to the other. CONCLUSION: The epidemiology of HD is different from that of NonHL, both showing a pattern similar to that of Latin American children.

Prevalence of high blood pressure and associated coronary risk factors in an adult population of Mexico City.

BACKGROUND: Several studies have addressed arterial hypertension prevalence in Mexico. However, few include an analysis of other types of hypertension and their associated risk factors. The present work describes the prevalence of high blood pressure (HBP), isolated systolic hypertension (ISH) and diastolic hypertension (DH) and their association to certain risk factors of cardiovascular disease in an adult population of Mexico City. METHODS: A cross-sectional study was performed on 825 subjects aged between 20 and 90 years, selected by multistage cluster sampling. HBP was diagnosed by previous history if systolic blood pressure was > or = 140 mmHg and/or diastolic blood pressure > or = 90 mmHg. The measurements taken included body mass index, waist-to-hip ratio, systolic and diastolic blood pressure, levels of insulin, glucose, trigylycerides, total cholesterol, high and low density lipoprotein cholesterol, and lipoprotein(a). RESULTS: Prevalence adjusted by age for HBP was 19.4%, for ISH, 4.7%, and for DH, 4.1%. Age had an important influence on HBP and ISH with a highly significant X2t. The profile of metabolic variables was modified according to sex and type of hypertension. Thus, in DH, metabolic variables were more affected than in other types of hypertension. CONCLUSIONS: Results in HBP prevalence in the present study were lower than in other surveys performed in Mexico. It must be noted, however, that much care should be taken to choose the strategy of subject selection, since results of the prevalence of a disease depend on it to a great extent. The ISH and DH and their association to risk factors must be studied thoroughly because they constitute different clinical entities.

Incidence of malignant neoplasms in children attending Social Security Hospitals in Mexico City.

An increase in neoplasms in Mexican children has been reported. In 1991, the incidence in children from Mexico City (MC) was 70 (x 10(6) child/year), although this rate might be underestimated. The aim of the present study was to estimate the incidence of malignant neoplasms in children resident in MC attending Social Security (SS) hospitals. This study was a retrospective hospital survey. All records of childhood malignant neoplasms diagnosed between 1992 and 1993 in the two SS hospitals which attend childhood neoplasms in MC were reviewed. Histopathological diagnoses were reevaluated and incidence rates (x 10(6) child/ year) in terms of age, sex, and place of residence were estimated. A total of 667 cases were found for the period of study, of which 199 corresponded to residents of MC. The neoplasms with highest prevalence were leukemias (39.2%), lymphomas (17.6%), and central nervous system tumors (12.6%). A general incidence of 94.3 was found, which was highest in children under 5 years of age. Leukemias had an incidence of 36.4, lymphomas of 15.2, and central nervous system tumors of 12.0. Prevalence was higher in boys (male/female ratio of 1.6). As for the place of residence, the highest incidence corresponded to children living in the southern areas of MC. Eighty percent of the leukemias were acute lymphoblastic, while 54% of solid neoplasms were classified as stages III and IV. In conclusion, the incidence of malignant neoplasms in children resident in MC treated at SS hospitals is consistent with that found worldwide, and also with the Latin American pattern.