Environmental factors and childhood acute leukemias and lymphomas

Evidence of spatial clustering of childhood acute lymphoblastic leukemia cases in Greater Mexico City: report from the Mexican Inter-Institutional Group for the identification of the causes of childhood leukemia

Background

A heterogeneous geographic distribution of childhood acute lymphoblastic leukemia (ALL) cases has been described, possibly, related to the presence of different environmental factors. The aim of the present study was to explore the geographical distribution of childhood ALL cases in Greater Mexico City (GMC).

Methods

A population-based case-control study was conducted. Children <18 years old, newly diagnosed with ALL and residents of GMC were included. Controls were patients without leukemia recruited from second-level public hospitals, frequency-matched by sex, age, and health institution with the cases. The residence address where the patients lived during the last year before diagnosis (cases) or the interview (controls) was used for geolocation. Kulldorff's spatial scan statistic was used to detect spatial clusters (SCs). Relative risks (RR), associated p-value and number of cases included for each cluster were obtained.

Results

A total of 1054 cases with ALL were analyzed. Of these, 408 (38.7%) were distributed across eight SCs detected. A relative risk of 1.61 (p<0.0001) was observed for the main cluster. Similar results were noted for the remaining seven ones. Additionally, a proximity between SCs, electrical installations and petrochemical facilities was observed.

Conclusions

The identification of SCs in certain regions of GMC suggest the possible role of environmental factors in the etiology of childhood ALL.

The global burden of lymphoma: estimates from the Global Burden of Disease 2019 study

OBJECTIVES

The aim of this study was to describe the global trends in the burden of lymphoma from 1990 to 2019.

STUDY DESIGN

The data used in this study were from the Global Burden of Disease 2019 study.

METHODS

This study described the age-standardised rates of incidence, prevalence, mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life years (DALYs) of lymphoma (non-Hodgkin and Hodgkin's lymphoma, NHL and HL, respectively) annually from 1990 to 2019, stratified by sociodemographic index (SDI) and 21 world regions. The estimated annual percentage changes in these indexes were calculated.

RESULTS

In 2019, the age-standardised rates of HL per 100,000 population were lower than those of NHL in terms of incidence (1.1 vs 6.7 per 100,000 person-years, respectively) and prevalence (0.3 vs 5.7 per 100,000 person-years, respectively) but not mortality (21.6 vs 3.2 per 100,000 person-years, respectively). From 1999 to 2019, the global incidence of HL decreased and the incidence of NHL increased, and the prevalence of both HL and NHL increased, but the mortality rates decreased. When stratified by SDI, the incidence of HL decreased in all but middle-SDI regions, the mortality rate of HL decreased in all regions, and both the incidence and mortality rate of NHL increased in all but high-SDI regions. The prevalence of HL and NHL increased in all SDI regions, especially in middle-SDI regions. YLLs and DALYs of HL in all SDI regions and those of NHL in high-SDI regions decreased. YLDs slightly increased in middle- to high-SDI regions.

CONCLUSIONS

Lymphoma remains a major public health issue, and better prevention, precise identification, and promising treatments are vitally important.

Proteomic responses in the human dopaminergic LUHMES cell line to imidacloprid and its metabolites imidacloprid-olefin and desnitro-imidacloprid

Neonicotinoids (neonics) are amongst the most commonly used class of pesticides globally. In the United States, imidacloprid (IMI) is extensively used for agriculture and in other common applications such as house-hold pest control. Regular exposure to IMI, and several of its known metabolites including IMI-olefin and desnitro-imidacloprid (DN-IMI), has been shown to be harmful to many organisms including mammals, birds, and fish. Studies show that neonics bind human nicotinicacetylcholine receptors (nAChRs) and cause cellular toxicity. In the dopaminergic Lund human mesencephalic (LUHMES) cell line, IMI and other neonics (10-100 μM) have been recently shown to activate intracellular calcium signaling through nAChRs. Thus, we examined proteomic responses of LUHMES cells to a 48-h treatment with 50 μM IMI, IMI-olefin, or DN-IMI. Our findings show differential effects of these neonics on cellular protein expression. Bioinformatic analysis of significantly altered proteins indicates an effect of IMI, IMI-olefin, and DN-IMI on protein synthesis and ribosomal function. These findings suggest a role for protein synthesis and transcriptional regulation in neonic-mediated dopaminergic neurotoxicity.

Demographic and treatment risk factors of cancer-specific mortality among children and adolescent leukemia patients: a population-based study

Leukemia is the 15th most commonly diagnosed cancer and the 11th leading cause of cancer mortality. The high mortality rate of leukemia could be attributed to numerous factors. Therefore, we aimed to identify the demographic and treatment risk factors influencing mortality among patients diagnosed with leukemia. Patients' data from 1975 to 2016 were collected from the Surveillance, Epidemiology, and End Results (SEER) database. We used the Person's chi-square test to examine the associations among the categorical variables. Kaplan-Meier and Cox regression were applied for univariate and multivariate analyses. Standardized mortality ratios were utilized to compare the mortality rates of leukemia patients and the general US population. We carried out the statistical analysis using SPSS software. A total of 18,880 patients with leukemia were studied. The leukemia incidence was increased in children than in adolescents. Acute lymphoid leukemia (ALL) was the most common type diagnosed among children and adolescents: 10,331 and 4112 patients, respectively. All mortality ratios were significantly higher in leukemia patients compared to the US population. The risk of mortality among leukemia patients was higher among adolescents, females, Black, urban areas with a 20,000 population, and patients not receiving chemotherapy. In contrast, the mortality risk was decreased in patients with higher family incomes, those not treated with radiation, and diagnosed from 2000 to 2016. In conclusion, Leukemia's incidence increases with time. Adolescents, males, Black, in some urban areas, and patients who have not received chemotherapy had the highest mortality risk among leukemia patients.

Residential Exposure to PM2.5 Components and Risk of Childhood Non-Hodgkin Lymphoma in Denmark: A Nationwide Register-Based Case-Control Study

In a recent study, we observed an increased risk of childhood non-Hodgkin lymphoma (NHL) associated with exposure to fine atmospheric particulate matter (PM_2.5) and black carbon (BC). In this nationwide register-based case-control study, we focus on specific components of PM_2.5 in relation to childhood NHL in Denmark (1981–2013) by identifying all incidents of childhood NHL cases in the Danish Cancer Registry (n = 170) and four (cancer-free) randomly selected controls matched by date of birth and sex. We applied PM_2.5 concentrations and the following sub-components: secondary organic aerosols (SOA), secondary inorganic aerosols (SIA; i.e., NO₃⁻, NH₄⁺ and SO₄²⁻), BC, organic carbon (OC) and sea salt. We calculated a time-weighted exposure average from birth to index-date at all addresses. Odds ratios (ORs) were adjusted for register-based socio-demographic variables. We observed adjusted ORs and 95% confidence intervals (95% CI) of 2.05 (1.10, 3.83) per interquartile range (IQR, 4.83 µg/m³) PM_2.5 and 1.73 (0.68, 4.41) per IQR (3.71 µg/m³) SIA, 0.95 (0.71, 1.29) per IQR (0.05 µg/m³) SOA, 1.22 (1.02, 1.46) per IQR (0.39 µg/m³) BC, 1.02 (0.83, 1.26) per IQR (0.56 µg/m³) OC and 1.01 (0.79, 1.30) per IQR (0.87 µg/m3) sea salt, respectively. The estimates were attenuated after adjustment for PM_2.5, whereas the OR for PM_2.5 remained increased regardless of adjustment for specific components. The findings indicate that the previously observed relation between PM_2.5 and childhood NHL may be related to BC (as reported in our previous study) but also partly to SIA, but the role of specific chemical components of PM_2.5 remains ambiguous.

Childhood Leukemia in Small Geographical Areas and Proximity to Industrial Sources of Air Pollutants in Three Colombian Cities

Acute leukemia is the most common childhood cancer and has been associated with exposure to environmental carcinogens. This study aimed to identify clusters of acute childhood leukemia (ACL) cases and analyze their relationship with proximity to industrial sources of air pollution in three capital cities in Colombia during 2000-2015. Incident ACL cases were obtained from the population cancer registries for the cities of Bucaramanga, Cali, and Medellín. The inventory of industrial sources of emissions to the air was obtained from the regional environmental authorities and industrial conglomerates were identified. The Kulldorf's circular scan test was used to detect city clusters and to identify clusters around industrial conglomerates. Multivariable spatial modeling assessed the effect of distance and direction from the industrial conglomerates controlling for socioeconomic status. We identified industrials sectors within a buffer of 1 km around industrial conglomerates related to the ACL clusters. Incidence rates showed geographical heterogeneity with low spatial autocorrelation within cities. The spatio-temporal tests identified one cluster in each city. The industries located within 1 km around the ACL clusters identified in the three cities represent different sectors. Exposure to air pollution from industrial sources might be contributing to the incidence of ACL cases in urban settings in Colombia.

Maternal exposure to pesticides and risk of childhood lymphoma in France: A pooled analysis of the ESCALE and ESTELLE studies (SFCE)

BACKGROUND

Few studies have assessed the relation between maternal prenatal pesticides use and childhood lymphoma risk, some reporting a positive association with non-Hodgkin lymphoma (NHL). We investigated the association between maternal exposure to pesticides during pregnancy and childhood Hodgkin (HL) and non-Hodgkin lymphoma.

METHODS

We pooled data from the two French national population-based case-control studies ESCALE (2003-2004) and ESTELLE (2010-2011). Data on domestic and occupational exposures to pesticides during pregnancy were obtained through standardised maternal interviews. Logistic regression models were used to compute odds ratios (OR) and 95% confidence intervals (CI) for HL and NHL, by pesticide category adjusted for potential confounders. Analyses by histological subtypes were also performed.

RESULTS

We included 328 H L, 305 non-Hodgkin NHL and 2,415 controls. Around 40% of control mothers reported having used pesticides during index pregnancy, of whom 95% reported insecticides use. Maternal use of herbicides and fungicides occurred mostly in combination with insecticides. Insecticides use was more frequently reported in cases than controls (OR_NHL = 1.6 [95%CI 1.3-2.1], p = 0.0001; OR_HL = 1.3 [95%CI 1.0-1.7], p = 0.03). This association appeared more marked for Burkitt lymphoma and mixed cellularity classical HL. No obvious association was observed with occupational pesticides exposure during pregnancy.

CONCLUSION

These results suggest that maternal domestic use of insecticides during pregnancy might be related to both childhood NHL and HL. Further larger studies are urgently needed.

Identification of significant risks in pediatric acute lymphoblastic leukemia (ALL) through machine learning (ML) approach

Pediatric acute lymphoblastic leukemia (ALL) through machine learning (ML) technique was analyzed to determine the significance of clinical and phenotypic variables as well as environmental conditions that can identify the underlying causes of child ALL. Fifty pediatric patients (n = 50) included who were diagnosed with acute lymphoblastic leukemia (ALL) according to the inclusion and exclusion criteria. Clinical variables comprised of the blood biochemistry (CBC, LFTs, RFTs) results, and distribution of type of ALL, i.e., T ALL or B ALL. Phenotypic data included the age, sex of the child, and consanguinity, while environmental factors included the habitat, socioeconomic status, and access to filtered drinking water. Fifteen different features/attributes were collected for each case individually. To retrieve most useful discriminating attributes, four different supervised ML algorithms were used including classification and regression trees (CART), random forest (RM), gradient boosted machine (GM), and C5.0 decision tree algorithm. To determine the accuracy of the derived CART algorithm on future data, a ten-fold cross validation was performed on the present data set. The ALL was common in children of age below 5 years in male patients whole belonged to middle class family of rural areas. (B-ALL) was most frequent as compared with T-ALL. The consanguinity was present in 54% of cases. Low levels of platelets and hemoglobin and high levels of white blood cells were reported in child ALL patients. CART provided the best and complete fit for the entire data set yielding a 99.83% model fit accuracy, and a misclassification of 0.17% on the entire sample space, while C5.0 reported 98.6%, random forest 94.44%, and gradient boosted machine resulted in 95.61% fitting. The variable importance of each primary discriminating attribute is platelet 43%, hemoglobin 24%, white blood cells 4%, and sex of the child 4%. An overall accuracy of 87.4% was recorded for the classifier. Platelet count abnormality can be considered as a major factor in predicting pediatric ALL. The machine learning algorithms can be applied efficiently to provide details for the prognosis for better treatment outcome. Graphical Abstract Identification of significant risks in pediatric acute lymphoblastic leukemia (ALL) through machine learning (ML) approach.

Childhood leukaemia incidence and trends in a Middle Eastern country during 1980-2014: a population-based study

BACKGROUND

This retrospective cohort study examines the trends in childhood leukaemia age-standardized incidence rates (ASIRs) (per million person-years) using cases which were diagnosed at age 0-19 years from 1980 to 2014 and recorded in the Kuwait Cancer Control Center (KCCC) registry.

METHODS

Childhood leukaemia age-specific incidence rates overall and by sub-cohorts defined by age (0-4, 5-9, 10-14, and 15-19 years), sex (male, female) and nationality (Kuwaiti, non-Kuwaiti) were computed and age-standardized. Joinpoint regression models were used to evaluate trends in childhood leukaemia ASIRs. Average annual percent change (AAPC) and its 95% confidence interval (CI) were used to interpret the observed trends.

RESULTS

During the study period, 1077 childhood leukaemia cases of 32.3 million person-years were diagnosed. From 1980 to 2014, the average annual childhood leukaemia ASIR was 53.1 (95% CI 20.9, 85.2). Overall childhood leukaemia ASIRs significantly decreased on average by 6.8% per year (AAPC =  -6.8; 95% CI -12.1, -1.1; p = 0.02) from 1980 to 1993, but a marginally significant increase in ASIRs from 1993 to 2014 was recorded (AAPC = 2.5; 95% CI -0.5, 5.5; p = 0.10). During the entire period, childhood leukaemia ASIRs trends significantly (p < 0.05) increased among 6 of 16 sub-cohorts, which was more pronounced among females and 10-14-year-old children.

CONCLUSIONS

Overall, ASIRs significantly increased from 1993 to 2014, which specifically seems to be driven by an increase in ASIRs among females and 10-14 -year-old children. These increasing trends underscore the potential involvement of a range of exposures. Future studies on unravelling such factors may help develop preventive measures to minimize childhood leukaemia risk in this and similar settings in the region.

Infectious Agents in Bovine Red Meat and Milk and Their Potential Role in Cancer and Other Chronic Diseases

Red meat and dairy products have frequently been suggested to represent risk factors for certain cancers, chronic neurodegenerative diseases, and autoimmune and cardiovascular disorders. This review summarizes the evidence and investigates the possible involvement of infectious factors in these diseases. The isolation of small circular single-stranded DNA molecules from serum and dairy products of Eurasian Aurochs (Bos taurus)-derived cattle, obviously persisting as episomes in infected cells, provides the basis for further investigations. Gene expression of these agents in human cells has been demonstrated, and frequent infection of humans is implicated by the detection of antibodies in a high percentage of healthy individuals. Epidemiological observations suggest their relationship to the development multiple sclerosis, to heterophile antibodies, and to N-glycolylneuraminic acid (Neu5Gc) containing cell surface receptors.

Case-control study of paternal occupational exposures and childhood lymphoma in Great Britain, 1962-2010

BACKGROUND

This nationwide study investigates associations between paternal occupational exposure and childhood lymphoma.

METHODS

The UK National Registry of Childhood Tumours provided cases of childhood lymphoma born and diagnosed in Great Britain 1962-2010. Control births, unaffected by childhood cancer, were matched on sex, birth period and birth registration sub-district. Fathers' occupations were assigned to one or more of 33 exposure groups and also coded for occupational social class.

RESULTS

We analysed 5033 childhood lymphoma cases and 4990 controls. Total lymphoma and the subgroups Hodgkin, Burkitt and non-Hodgkin lymphoma were considered separately. No one exposure was significantly associated with increased risk within all subgroups and for total lymphoma. However, exposure to "ceramics and glass" was significantly associated with increased risk of total lymphoma, Hodgkin and non-Hodgkin lymphoma. Paternal lead exposure was associated with Burkitt lymphoma and exposure to metal fumes was associated with Hodgkin lymphoma.

CONCLUSIONS

This study provides no support for previous suggestions of an association between childhood lymphoma and paternal occupational exposure to pesticides, solvents/hydrocarbons or infections potentially transmitted by father's social contacts. An association with exposure to "ceramics and glass" was noted for the two major lymphoma subtypes together comprising 80% of total lymphoma.

Minimally Invasive Treatment of Sporadic Burkitt's Lymphoma Causing Ileocaecal Invagination

Introduction

Primary NHL (non-Hodgkin lymphoma) of the colon represents only 0.2% to 1.2% of all colonic malignancies. Burkitt's lymphoma (BL) is usually a disease reported in children and young people, most of them associated with EBV or HIV infection. We describe a rare case of intestinal obstruction due to sporadic Burkitt's lymphoma causing ileocaecal invagination explaining our experience Methods. A 31-year-old man presented with diffuse colic pain and weight loss. Clinical examination revealed an abdominal distension with pain in the right iliac fossa. Colonoscopy documented a caecal large lesion with ulcerated mucosa. Computed tomography (CT) have shown a 60 × 50 mm right colic parietal lesion with signs of ileocolic intussusception.

Results

Laparoscopic right hemicolectomy was performed. Postoperative period was uneventful. CD20+ high-grade B-cell Burkitt's lymphoma was confirmed by immunohistochemistry (CD20+, CD79+, and CD10+) and FISH test (t (8;14) (q24; q32). The patient was subsequently treated with adjuvant combination chemotherapy (Hyper-CVAD) and is alive and disease-free at 8 months follow-up.

Discussion

Adult sporadic Burkitt's lymphoma (BL) causing intestinal obstruction due to ileocaecal intussusception is an extremely rare occurrence and a diagnostic dilemma. Despite the surgical approach is selected based on patient's conditions and surgeon's expertise, minimally invasive method could be preferred.

Childhood and adolescent lymphoma in Spain: incidence and survival trends over 20 years

BACKGROUND

Lymphoma is the third most common malignancy in children (0-14 years) and the first in adolescents (15-19 years). This population-based study-the largest ever done in Spain-analyses incidence and survival of lymphomas among Spanish children and adolescents.

PATIENTS AND METHODS

1664 lymphoma cases (1983-2007) for incidence and 1030 for survival (1991-2005) followed until 31/12/2010, were provided by 11 cancer registries. Age-adjusted incidence rates (ASRw) to the world standard population were obtained; incidence trends were modelled using the Joinpoint programme, observed survival (OS) was estimated with Kaplan-Meier and trends tested with a log-rank test. Results are presented according to the International Classification of Childhood Cancer-3.

RESULTS

In Spain, the ASRw_0-14 for lymphomas was 17.5 per 1.000.000 child-years and 50.0 the specific rate for adolescents. Overall incidence increased significantly during 1983-1997 with no increases thereafter. Patients over 9 years old showed significant rising trends for all subtypes, except for Burkitt lymphoma (BL) in adolescents. During 2001-2005 (age 0-19 years), 5-year OS was 94 (90-98), 73 (64-83) and 86 (78-94) for Hodgkin lymphoma (HL), non-Hodgkin lymphoma (NHL) and BL, respectively. No improvement in survival was found. The incidence in Spain was higher than overall European rates, but within the range of that in Southern Europe. Comparing OS in Spain 1991-1995 and 2001-2005 with results for Europe of the Automated Childhood Cancer Information System (ACCIS) (1988-1997) and the European cancer registry-based study on survival and care of cancer patients (EUROCARE) (2000-2007), it was similar for HL and lower for NHL and BL.

CONCLUSIONS

Systematic monitoring and analysis of lymphoma paediatric data would provide clinical and epidemiological information to improve the health care of these patients and the outcomes for these malignancies in Spain.

A Case of Jejunal Intussusception caused by Burkitt Lymphoma in an Acquired Immunodeficiency Syndrome Patient

Non-Hodgkin's lymphoma of B-cell type is the second most common neoplasm after Kaposi's sarcoma among patients with human immunodeficiency virus infection. Most non-Hodgkin's lymphoma cases that are associated with acquired immunodeficiency syndrome (AIDS) involve extranodal sites, especially the digestive tract and the central nervous system. We report a case of multiple jejunal intussusception caused by Burkitt lymphoma in a 42-year-old AIDS patient. Upper gastrointestinal endoscopy and surgical biopsy were performed and a complete diagnostic study including histological and immunohistochemical analyses showed Burkitt lymphoma.

Road Traffic Pollution and Childhood Leukemia: A Nationwide Case-control Study in Italy

BACKGROUND

The association of childhood leukemia with traffic pollution was considered in a number of studies from 1989 onwards, with results not entirely consistent and little information regarding subtypes.

AIM OF THE STUDY

We used the data of the Italian SETIL case-control on childhood leukemia to explore the risk by leukemia subtypes associated to exposure to vehicular traffic.

METHODS

We included in the analyses 648 cases of childhood leukemia (565 Acute lymphoblastic-ALL and 80 Acute non lymphoblastic-AnLL) and 980 controls. Information on traffic exposure was collected from questionnaire interviews and from the geocoding of house addresses, for all periods of life of the children.

RESULTS

We observed an increase in risk for AnLL, and at a lower extent for ALL, with indicators of exposure to traffic pollutants. In particular, the risk was associated to the report of closeness of the house to traffic lights and to the passage of trucks (OR: 1.76; 95% CI 1.03-3.01 for ALL and 6.35; 95% CI 2.59-15.6 for AnLL). The association was shown also in the analyses limited to AML and in the stratified analyses and in respect to the house in different period of life.

CONCLUSIONS

Results from the SETIL study provide some support to the association of traffic related exposure and risk for AnLL, but at a lesser extent for ALL. Our conclusion highlights the need for leukemia type specific analyses in future studies. Results support the need of controlling exposure from traffic pollution, even if knowledge is not complete.

Parental Exposure to Workplace Carcinogens and the Risk of Development of Acute Leukemia in Infants. Case-Control Study

BACKGROUND AND AIMS

Occupational exposure of parents to carcinogens is of great interest in the etiology of leukemias. Evidence of the impact of such exposure on infants or small children is scarce. Here we estimated whether occupational exposure of parents to carcinogens could be a risk factor for leukemias in their children.

METHODS

Cases of acute leukemia (AL) in infants ≤24 months old diagnosed in Mexico City (1998-2013) were included in a population-based, case-control study. Each of the 195 cases was matched with at least one healthy child (n = 369). For each of four exposure windows studied, the degree of exposure to carcinogens was determined for both parents by using a validated occupational exposure index. An unconditional logistic regression was carried out.

RESULTS

Odds ratios (OR) and the 95% confidence intervals (CI) of the overall occupational exposure for parents during the four exposure windows indicated no association with risk of AL in their children. Pre-conception, the OR by the father 0.77 (0.49-1.21), by the mother 1.03 (0.50-2.11); during pregnancy, father 0.66 (0.38-1.15), mother 1.79 (0.46-6.90); during breastfeeding, father 0.75 (0.43-1.30), mother 0.96 (0.21-4.30); and after birth, father 0.74 (0.45-1.22), mother 0.90 (0.24-3.32). The statistical power of the sample size to identify an OR ≥2 and an exposure of ≥10% among controls was 78%.

CONCLUSIONS

These data support the idea that parents' occupational exposure during any of the periods studied was not a risk factor contributing to the etiology of AL in infants ≤24 months of age.

Estimating the Proportion of Childhood Cancer Cases and Costs Attributable to the Environment in California

OBJECTIVES

To estimate the proportion of cases and costs of the most common cancers among children aged 0 to 14 years (leukemia, lymphoma, and brain or central nervous system tumors) that were attributable to preventable environmental pollution in California in 2013.

METHODS

We conducted a literature review to identify preventable environmental hazards associated with childhood cancer. We combined risk estimates with California-specific exposure prevalence estimates to calculate hazard-specific environmental attributable fractions (EAFs). We combined hazard-specific EAFs to estimate EAFs for each cancer and calculated an overall EAF. Estimated economic costs included annual (indirect and direct medical) and lifetime costs.

RESULTS

Hazards associated with childhood cancer risks included tobacco smoke, residential exposures, and parental occupational exposures. Estimated EAFs for leukemia, lymphoma, and brain or central nervous system cancer were 21.3% (range = 11.7%-30.9%), 16.1% (range = 15.0%-17.2%), and 2.0% (range = 1.7%-2.2%), respectively. The combined EAF was 15.1% (range = 9.4%-20.7%), representing $18.6 million (range = $11.6 to $25.5 million) in annual costs and $31 million in lifetime costs.

CONCLUSIONS

Reducing environmental hazards and exposures in California could substantially reduce the human burden of childhood cancer and result in significant annual and lifetime savings.

Geographical Correlations between Indoor Radon Concentration and Risks of Lung Cancer, Non-Hodgkin's Lymphoma, and Leukemia during 1999-2008 in Korea

Indoor radon is the second most important risk factor for lung cancer and may also be a risk factor for hematopoietic cancers, particularly in children and adolescents. The present study measured indoor radon concentration nationwide at 5553 points during 1989–2009 and spatially interpolated using lognormal kriging. The incidences of lung cancer, non-Hodgkin’s lymphoma (NHL), and leukemia, stratified by sex and five-year age groups in each of the 234 administrative regions in the country during 1999–2008, were obtained from the National Cancer Registry and used to calculate the standardized incidence ratios. After considering regional deprivation index values and smoking rates by sex in each region as confounding variables, the cancer risks were estimated based on Bayesian hierarchical modeling. We found that a 10 Bq/m³ increase in indoor radon concentration was associated with a 1% increase in the incidence of lung cancer in male and a 7% increase in NHL in female children and adolescents in Korea aged less than 20 years. Leukemia was not associated with indoor radon concentration. The increase in NHL risk among young women requires confirmation in future studies, and the radon control program should consider children and adolescents.

Childhood hematologic cancer and residential proximity to oil and gas development

Background

Oil and gas development emits known hematological carcinogens, such as benzene, and increasingly occurs in residential areas. We explored whether residential proximity to oil and gas development was associated with risk for hematologic cancers using a registry-based case-control study design.

Methods

Participants were 0–24 years old, living in rural Colorado, and diagnosed with cancer between 2001–2013. For each child in our study, we calculated inverse distance weighted (IDW) oil and gas well counts within a 16.1-kilometer radius of residence at cancer diagnosis for each year in a 10 year latency period to estimate density of oil and gas development. Logistic regression, adjusted for age, race, gender, income, and elevation was used to estimate associations across IDW well count tertiles for 87 acute lymphocytic leukemia (ALL) cases and 50 non-Hodgkin lymphoma (NHL) cases, compared to 528 controls with non-hematologic cancers.

Findings

Overall, ALL cases 0–24 years old were more likely to live in the highest IDW well count tertiles compared to controls, but findings differed substantially by age. For ages 5–24, ALL cases were 4.3 times as likely to live in the highest tertile, compared to controls (95% CI: 1.1 to 16), with a monotonic increase in risk across tertiles (trend p-value = 0.035). Further adjustment for year of diagnosis increased the association. No association was found between ALL for children aged 0–4 years or NHL and IDW well counts. While our study benefited from the ability to select cases and controls from the same population, use of cancer-controls, the limited number of ALL and NHL cases, and aggregation of ages into five year ranges, may have biased our associations toward the null. In addition, absence of information on O&G well activities, meteorology, and topography likely reduced temporal and spatial specificity in IDW well counts.

Conclusion

Because oil and gas development has potential to expose a large population to known hematologic carcinogens, further study is clearly needed to substantiate both our positive and negative findings. Future studies should incorporate information on oil and gas development activities and production levels, as well as levels of specific pollutants of interest (e.g. benzene) near homes, schools, and day care centers; provide age-specific residential histories; compare cases to controls without cancer; and address other potential confounders, and environmental stressors.

Breastfeeding as a Protective Effect Against Childhood Leukemia and Lymphoma

Background

Over the past several years, breastfeeding has been associated with many benefits as well as protective effects against many diseases. There is limited evidence for the relationship between breastfeeding and the incidence of leukemia.

Objectives

In this study, we evaluate the correlation of childhood leukemia and lymphoma with breastfeeding duration in children in southern Iran.

Patients and methods

Through this case control study, we compared 123 patients with leukemia and lymphoma to a control group of 137 healthy children. Statistical analysis was done using the Chi-square test and t-test as well as logistic regression methods. A P-value of less than 0.05 was considered significant.

Results

Our findings showed that breastfeeding duration had no significant difference between cases and controls. However, the rural living percentage in patients with leukemia and lymphoma was higher than in the control group (39.8% versus 14.6% [P < 0.001 and OR = 3.87]) and parents’ exposure to chemical materials during the war between Iran and Iraq was higher in sick patients (6.5% versus 0% [OR = 20.2%]).

Conclusions

The current study showed that breastfeeding duration has no protective effect against childhood leukemia and lymphoma. In addition, we suggest that some factors such as living in a rural area, smoking during pregnancy, parents’ exposure to chemical materials and low socioeconomic status can increase the incidence rate of childhood leukemia and lymphoma.

Parental, In Utero, and Early-Life Exposure to Benzene and the Risk of Childhood Leukemia: A Meta-Analysis

Benzene is an established cause of adult leukemia, but whether it is associated with childhood leukemia remains unclear. We conducted a meta-analysis in which we reviewed the epidemiologic literature on this topic and explored causal inference, bias, and heterogeneity. The exposure metrics that we evaluated included occupational and household use of benzenes and solvents, traffic density, and traffic-related air pollution. For studies of occupational and household product exposure published from 1987 to 2014, the summary relative risk for childhood leukemia was 1.96 (95% confidence interval (CI): 1.53, 2.52; n = 20). In these studies, the summary relative risk was higher for acute myeloid leukemia (summary relative risk (sRR) = 2.34, 95% CI: 1.72, 3.18; n = 6) than for acute lymphoblastic leukemia (sRR = 1.57; 95% CI: 1.21, 2.05; n = 14). The summary relative risk was higher for maternal versus paternal exposure, in studies that assessed benzene versus all solvents, and in studies of gestational exposure. In studies of traffic density or traffic-related air pollution published from 1999 to 2014, the summary relative risk was 1.48 (95% CI: 1.10, 1.99; n = 12); it was higher for acute myeloid leukemia (sRR = 2.07; 95% CI: 1.34, 3.20) than for acute lymphoblastic leukemia (sRR = 1.49; 95% CI: 1.07, 2.08) and in studies that involved detailed models of traffic pollution (sRR = 1.70; 95% CI: 1.16, 2.49). Overall, we identified evidence of associations between childhood leukemia and several different potential metrics of benzene exposure.

Residential Radon Exposure and Incidence of Childhood Lymphoma in Texas, 1995-2011

There is warranted interest in assessing the association between residential radon exposure and the risk of childhood cancer. We sought to evaluate the association between residential radon exposure and the incidence of childhood lymphoma in Texas. The Texas Cancer Registry (n = 2147) provided case information for the period 1995–2011. Denominator data were obtained from the United States Census. Regional arithmetic mean radon concentrations were obtained from the Texas Indoor Radon Survey and linked to residence at diagnosis. Exposure was assessed categorically: ≤25th percentile (reference), >25th to ≤50th percentile, >50th to ≤75th percentile, and >75th percentile. Negative binomial regression generated adjusted incidence rate ratios (aIRR) and 95% confidence intervals (CI). We evaluated lymphoma overall and by subtype: Hodgkin (HL; n = 1248), Non-Hodgkin excluding Burkitt (non-BL NHL; n = 658), Burkitt (BL; n = 241), and Diffuse Large B-cell (DLBCL; n = 315). There was no evidence that residential radon exposure was positively associated with lymphoma overall, HL, or BL. Areas with radon concentrations >75th percentile had a marginal increase in DLBCL incidence (aIRR = 1.73, 95% CI: 1.03–2.91). In one of the largest studies of residential radon exposure and the incidence of childhood lymphoma, we found little evidence to suggest a positive or negative association; an observation consistent with previous studies.

Antibiotic use from conception to diagnosis of child leukaemia as compared to the background population: A nested case-control study

BACKGROUND

The role of infection in the aetiology of childhood leukaemia is unknown. We used prescriptions of antibiotics from Danish pharmacies as a proxy measure for the occurrence of infections.

PROCEDURE

We investigated the association between exposure to antibiotics, from conception to leukaemia diagnosis, and the risk of leukaemia. Incident cases of leukaemia among children in Denmark, 1995-2008, with mothers having their earliest conception date in 1995, were individually matched to population controls by age, sex and municipality. Conditional logistic regression analyses assessed antibiotic redemptions in different time periods from conception up to 6 months before the diagnoses of all leukaemia types, acute lymphoblastic leukaemia [ALL] and ALL in 2- to 5-year-old children, adjusting for several potential confounders.

RESULTS

A total of 120/360 (33.3%) leukaemia mothers and 1,081/3,509 (30.8%) control mothers redeemed antibiotics during pregnancy (P = 0.32). For children, the equivalent numbers were 276 (76.7%) and 2,665 (75.9%) (P = 0.76). Histograms of antibiotic redemptions showed no temporal differences between leukaemia mothers/children and controls, which was confirmed in adjusted regression analyses (OR [95% CI]: 1.02 [0.75-1.38]). Only antibiotics redeemed during the first year after birth differed from this (OR [95% CI] for ALL diagnosed in 2- to 5-year-old children: 0.46 [0.31-0.66]).

CONCLUSIONS

In this hypothesis generating study, the similar amount and pattern of antibiotic redemptions in children with and without leukaemia indicate that infections play a minor role in the aetiology of childhood leukaemia. However, less antibiotic redemptions during the first year of life conform to Greaves' 'delayed infection hypothesis'.

Prenatal recruitment of participants for a birth cohort study including cord blood collection: results of a feasibility study in Bremen, Germany

BACKGROUND

Prospective birth cohort studies comprising follow up of children from pregnancy or birth over a long period of time, and collecting various biological samples at different times through the life-course offer a promising approach to enhance etiologic knowledge of various diseases. Especially for those where early lifetime exposures and conditions are thought to play an important role. The collection and storage of biological samples is a critical component in epidemiological studies, notably for research regarding prenatal exposures to various environmental factors as well as for DNA extraction. Our feasibility study for a birth cohort within the scope of etiology of childhood leukemia with prospective sampling of mothers and their future newborns aimed to investigate the willingness of pregnant women to participate in a birth cohort study involving collection of blood and umbilical cord blood samples. The overall aim was to develop practice-based research recommendations for a possible German birth cohort study.

METHODS

The study was conducted in Bremen, Germany, between January 2012 and March 2013. Pregnant women were eligible for recruitment if (i) their expected date of delivery was during the study recruitment phase (September 2012-February 2013), (ii) they planned to give birth at the cooperating hospital's obstetric unit and (iii) their knowledge of the German language was sufficient to understand study materials, details of participation and to fill out the prenatal self-administered questionnaire. Maternal blood and umbilical cord blood samples to be used for later research activities were collected and stored at a stem cell bank already collaborating with the hospital. 22 primary care gynecologists were invited to enroll pregnant women for the study and cooperation with one hospital was established. Expectant women were recruited during the last trimester of pregnancy, either during one of their prenatal care visits at their primary care gynecologist or later on in hospital by the attending obstetricians or project staff.

RESULTS

Of the 22 invited primary care gynecologists requested to enroll pregnant women for the study, 8 gynecologists actually collaborated. A total of 200 eligible women were invited to participate in the study, 48 (24%) of whom agreed. 34 women were enrolled by primary care gynecologists, with one gynecologist enrolling 26 women. Twelve of 14 women recruited via hospitals were enrolled by study staff. A total of 41 women consented to the collection of umbilical cord blood and maternal blood samples, and samples could be stored for 54% of them. Reason for non-participation were the uncertainty whether or not the full study would be conducted and the fact that the participants were not willing to decide for their children whether or not genetic information (cord blood) can be stored for research purposes.

CONCLUSION

Enrolling parents in a birth cohort study that includes biosampling is a challenge, but participation can be improved through close collaboration with primary care gynecologists and maternity hospitals. Cord blood collection may impede participation, especially when maternity hospitals offer an alternative option for cord blood donation.

SETIL: Italian multicentric epidemiological case-control study on risk factors for childhood leukaemia, non hodgkin lymphoma and neuroblastoma: study population and prevalence of risk factors in Italy

BACKGROUND

Aetiology of childhood leukaemia and childhood neoplasm is poorly understood. Information on the prevalence of risk factors in the childhood population is limited. SETIL is a population based case-control study on childhood leukaemia, conducted with two companion studies on non-Hodgkin Lymphoma (NHL) and neuroblastoma. The study relies on questionnaire interviews and 50 Hz magnetic field (ELF-MF) indoor measurements. This paper discusses the SETIL study design and includes descriptive information.

METHODS

The study was carried out in 14 Italian regions (78.3% of Italian population aged 0-10). It included leukaemia, NHL and neuroblastoma cases incident in 0-10 year olds in 1998-2001, registered by the Italian Association of Paediatric Haematology and Oncology (AIEOP) (accrual over 95% of estimated incidence). Two controls for each leukaemia case were randomly sampled from the Local Health Authorities rolls, matched by gender, birthdate and residence. The same controls were used in NHL and neuroblastoma studies. Parents were interviewed at home on: physical agents (ELF-MF and ionizing radiation), chemicals (smoking, solvents, traffic, insecticides), occupation, medical and personal history of children and parents, infectious diseases, immunizations and associated factors. Occupational exposure was collected using job specific modules. ELF-MF was measured in the main rooms (spot measurement) and close to child's bed (48 hours measurement).

RESULTS

The study included: 683 leukaemia cases (87% ALL, 13% AnLL), 97 NHL, 155 neuroblastomas, and 1044 controls.

CONCLUSIONS

SETIL represents a data source on exposure of Italian children to a broad array of potential carcinogenic factors.

Parental occupational pesticide exposure and the risk of childhood leukemia in the offspring: findings from the childhood leukemia international consortium

Maternal occupational pesticide exposure during pregnancy and/or paternal occupational pesticide exposure around conception have been suggested to increase risk of leukemia in the offspring. With a view to providing insight in this area we pooled individual level data from 13 case-control studies participating in the Childhood Leukemia International Consortium (CLIC). Occupational data were harmonized to a compatible format. Pooled individual analyses were undertaken using unconditional logistic regression. Using exposure data from mothers of 8,236 cases, and 14,850 controls, and from fathers of 8,169 cases and 14,201 controls the odds ratio (OR) for maternal exposure during pregnancy and the risk of acute lymphoblastic leukemia (ALL) was 1.01 [95% confidence interval (CI) 0.78, 1.30] and for paternal exposure around conception 1.20 (95% 1.06, 1.38). For acute myeloid leukemia (AML), the OR for maternal exposure during pregnancy was 1.94 (CI 1.19, 3.18) and for paternal exposure around conception 0.91 (CI 0.66, 1.24.) based on data from 1,329 case and 12,141 control mothers, and 1,231 case and 11,383 control fathers. Our finding of a significantly increased risk of AML in the offspring with maternal exposure to pesticides during pregnancy is consistent with previous reports. We also found a slight increase in risk of ALL with paternal exposure around conception which appeared to be more evident in children diagnosed at the age of 5 years or more and those with T cell ALL which raises interesting questions on possible mechanisms.

Parental occupational paint exposure and risk of childhood leukemia in the offspring: findings from the Childhood Leukemia International Consortium

PURPOSE

It has been suggested that parental occupational paint exposure around the time of conception or pregnancy increases the risk of childhood leukemia in the offspring.

METHODS

We obtained individual level data from 13 case-control studies participating in the Childhood Leukemia International Consortium. Occupational data were harmonized to a compatible format. Meta-analyses of study-specific odds ratios (ORs) were undertaken, as well as pooled analyses of individual data using unconditional logistic regression.

RESULTS

Using individual data from fathers of 8,185 cases and 14,210 controls, the pooled OR for paternal exposure around conception and risk of acute lymphoblastic leukemia (ALL) was 0.93 [95% confidence interval (CI) 0.76, 1.14]. Analysis of data from 8,156 ALL case mothers and 14,568 control mothers produced a pooled OR of 0.81 (95% CI 0.39, 1.68) for exposure during pregnancy. For acute myeloid leukemia (AML), the pooled ORs for paternal and maternal exposure were 0.96 (95% CI 0.65, 1.41) and 1.31 (95% CI 0.38, 4.47), respectively, based on data from 1,231 case and 11,392 control fathers and 1,329 case and 12,141 control mothers. Heterogeneity among the individual studies ranged from low to modest.

CONCLUSIONS

Null findings for paternal exposure for both ALL and AML are consistent with previous reports. Despite the large sample size, results for maternal exposure to paints in pregnancy were based on small numbers of exposed. Overall, we found no evidence that parental occupational exposure to paints increases the risk of leukemia in the offspring, but further data on home exposure are needed.

Cross-space-time clustering of childhood cancer in Great Britain: evidence for a common aetiology

Previously, we identified space-time clustering in certain childhood cancers. This study aimed to determine whether there was cross-space-time clustering between different diagnostic groups. A total of 32,295 cases were diagnosed during 1969–1993. Cross-space-time clustering was analyzed by a second-order procedure based on Diggle's method. Locations were birth and diagnosis addresses. The following space-time combinations were examined: address and date of birth; address at birth and date of diagnosis; address and date of diagnosis. Cross-space-time clustering analyses considered clustering pairs of cases from two different diagnostic groups. Formal statistical significance was taken as p < 0.00067 and marginal significance 0.01 > p ≥ 0.00067. Based on address at birth and date of diagnosis, there was statistically significant cross-clustering between cases of HL and intracranial and intraspinal embryonal tumors (IIET), both aged 0–14 years (p < 0.0001). Based on address and date of birth, there was marginally significant cross-clustering between cases of lymphoid leukemia (LL) aged 5-14 years and Hodgkin lymphoma (HL) aged 0–14 years (p = 0.0019). Based on address and date of diagnosis there was marginally significant cross-clustering between cases of LL aged 1–4 years and soft tissue sarcoma (STS) aged 0–14 years (p = 0.0041). Findings from this study are consistent with possible common aetiological factors between different diagnostic groups. They suggest a common aetiology for the following pairs of diagnostic groups: HL and IIET; older cases of LL and HL; younger cases of LL and STS. The possibility of common infectious mechanisms should be explored.

Domestic radon exposure and risk of childhood cancer: a prospective census-based cohort study

BACKGROUND

In contrast with established evidence linking high doses of ionizing radiation with childhood cancer, research on low-dose ionizing radiation and childhood cancer has produced inconsistent results.

OBJECTIVE

We investigated the association between domestic radon exposure and childhood cancers, particularly leukemia and central nervous system (CNS) tumors.

METHODS

We conducted a nationwide census-based cohort study including all children < 16 years of age living in Switzerland on 5 December 2000, the date of the 2000 census. Follow-up lasted until the date of diagnosis, death, emigration, a child's 16th birthday, or 31 December 2008. Domestic radon levels were estimated for each individual home address using a model developed and validated based on approximately 45,000 measurements taken throughout Switzerland. Data were analyzed with Cox proportional hazard models adjusted for child age, child sex, birth order, parents' socioeconomic status, environmental gamma radiation, and period effects.

RESULTS

In total, 997 childhood cancer cases were included in the study. Compared with children exposed to a radon concentration below the median (< 77.7 Bq/m3), adjusted hazard ratios for children with exposure ≥ the 90th percentile (≥ 139.9 Bq/m3) were 0.93 (95% CI: 0.74, 1.16) for all cancers, 0.95 (95% CI: 0.63, 1.43) for all leukemias, 0.90 (95% CI: 0.56, 1.43) for acute lymphoblastic leukemia, and 1.05 (95% CI: 0.68, 1.61) for CNS tumors.

CONCLUSIONS

We did not find evidence that domestic radon exposure is associated with childhood cancer, despite relatively high radon levels in Switzerland.

Folic acid supplementation, MTHFR and MTRR polymorphisms, and the risk of childhood leukemia: the ESCALE study (SFCE)

PURPOSE

Fetal folate deficiency may increase the risk of subsequent childhood acute leukemia (AL), since folates are required for DNA methylation, synthesis, and repair, but the literature remains scarce. This study tested the hypothesis that maternal folic acid supplementation before or during pregnancy reduces AL risk, accounting for the SNPs rs1801133 (C677T) and rs1801131 (A1298C) in MTHFR and rs1801394 (A66G) and rs1532268 (C524T) in MTRR, assumed to modify folate metabolism.

METHODS

The nationwide registry-based case-control study, ESCALE, carried out in 2003-2004, included 764 AL cases and 1,681 controls frequency matched with the cases on age and gender. Information on folic acid supplementation was obtained by standardized telephone interview. The genotypes were obtained using high-throughput platforms and imputation for untyped polymorphisms. Odds ratios (OR) were estimated using unconditional regression models adjusted for potential confounders.

RESULTS

AL was significantly inversely associated with maternal folic acid supplementation before and during pregnancy (OR = 0.4; 95 % confidence interval: [0.3-0.6]). MTHFR and MTRR genetic polymorphisms were not associated with AL. However, AL was positively associated with homozygosity for any of the MTHFR polymorphisms and carriership of both MTRR variant alleles (OR = 1.6 [0.9-3.1]). No interaction was observed between MTHFR, MTRR, and maternal folate supplementation.

CONCLUSION

The study findings support the hypothesis that maternal folic acid supplementation may reduce the risk of childhood AL. The findings also suggest that the genotype homozygous for any of the MTHFR variants and carrying both MTRR variants could be a risk factor for AL.

Refuelling of vehicles, the use of wood burners and the risk of acute lymphoblastic leukaemia in childhood

It is plausible that exposure of the parents before birth or of the child to sources of benzene increases the risk of childhood acute lymphoblastic leukaemia (ALL). The aim of this analysis was to investigate whether refuelling a vehicle with petrol before birth or burning wood to heat the home before or after the child's birth increased the risk of childhood ALL. Data from 389 cases and 876 frequency-matched controls were analysed using unconditional logistic regression, adjusting for study matching factors and potential confounders. The odds ratio (OR) for the mother ever refuelling a vehicle with petrol for non-occupational purposes before or during the pregnancy was 0.97 [95% confidence interval (CI) 0.69, 1.38]. The OR for the father for this exposure in the year before conception was 0.88 [95% CI 0.52, 1.48]. The OR for use of a closed wood burner to heat the home in the year before or during pregnancy was 1.41 [95% CI 1.02, 1.94] and 1.25 [95% CI 0.92, 1.70] after birth. We found no evidence that non-occupational refuelling a vehicle with petrol in the year before or during pregnancy increased the risk of ALL in the offspring. There was weak evidence that burning wood in a closed burner to heat the home increased the risk, but there was no dose-response relationship and chance could explain the finding.

Road traffic and childhood leukemia: the ESCALE study (SFCE)

BACKGROUND

Traffic is a source of environmental exposures, including benzene, which may be related to childhood leukemia.

OBJECTIVES

A national registry-based case-control study [ESCALE (Etude Sur les Cancers et les Leucémies de l'Enfant, Study on Environmental and Genetic Risk Factors of Childhood Cancers and Leukemia)] carried out in France was used to assess the effect of exposure to road traffic exhaust fumes on the risk of childhood leukemia.

METHODS

Over the study period, 2003-2004, 763 cases and 1,681 controls < 15 years old were included, and the controls were frequency matched with the cases on age and sex. The ESCALE data were collected by a standardized telephone interview of the mothers. Various indicators of exposure to traffic and pollution were determined using the geocoded addresses at the time of diagnosis for the cases and of interview for the controls. Indicators of the distance from, and density of, main roads and traffic nitrogen dioxide (NO(2)) concentrations derived from traffic emission data were used. Odds ratios (ORs) were estimated using unconditional regression models adjusted for potential confounders.

RESULTS

Acute leukemia (AL) was significantly associated with estimates of traffic NO(2) concentration at the place of residence > 27.7 µg/m(3) compared with NO(2) concentration < 21.9 µg/m(3) [OR=1.2; confidence interval (CI), 1.0-1.5] and with the presence of a heavy-traffic road within 500 m compared with the absence of a heavy-traffic road in the same area (OR=2.0; 95% CI, 1.0-3.6). There was a significant association between AL and a high density of heavy-traffic roads within 500 m compared with the reference category with no heavy-traffic road within 500 m (OR=2.2; 95% CI, 1.1-4.2), with a significant positive linear trend of the association of AL with the total length of heavy-traffic road within 500 m.

CONCLUSION

This study supports the hypothesis that living close to heavy-traffic roads may increase the risk of childhood leukemia.

Spatio-temporal epidemiology: principles and opportunities

Space-time analysis of disease data has historically involved the search for patterns in aggregated data to identify how regions of high and low risk change through time. Space-time analysis of aggregated data has great value, but represents only a subset of space-time epidemiologic applications. Technological advances for tracking and mapping individuals (e.g., global positioning systems) have introduced mobile populations as an important element in space-time epidemiology. We review five domains critical to the developing field of spatio-temporal epidemiology: (1) spatio-temporal epidemiologic theory, (2) selection of appropriate spatial scale of analysis, (3) choice of spatial/spatio-temporal method for pattern identification, (4) individual-level exposure assessment in epidemiologic studies, and (5) assessment and consideration of locational and attribute uncertainty. This review provides an introduction to principles of space-time epidemiology and highlights future research opportunities.

Magnetic fields promote a pro-survival non-capacitative Ca2+ entry via phospholipase C signaling

The ability of magnetic fields (MFs) to promote/increase Ca(2+) influx into cells is widely recognized, but the underlying mechanisms remain obscure. Here we analyze how static MFs of 6 mT modulates thapsigargin-induced Ca(2+) movements in non-excitable U937 monocytes, and how this relates to the anti-apoptotic effect of MFs. Magnetic fields do not affect thapsigargin-induced Ca(2+) mobilization from endoplasmic reticulum, but significantly increase the resulting Ca(2+) influx; this increase requires intracellular signal transduction actors including G protein, phospholipase C, diacylglycerol lipase and nitric oxide synthase, and behaves as a non-capacitative Ca(2+) entry (NCCE), a type of influx with an inherent signaling function, rather than a capacitative Ca(2+) entry (CCE). All treatments abrogating the extra Ca(2+) influx also abrogate the anti-apoptotic effect of MFs, demonstrating that MF-induced NCCE elicits an anti-apoptotic survival pathway.

A review of the potential association between childhood leukemia and benzene

Chronic exposure to high concentrations of benzene is an established cause of acute myeloid leukemia (AML) in occupationally exposed workers. Based on this association, it is not unreasonable to assume that children could also get AML if they were exposed to comparable levels of benzene. Fortunately, reports of such exposures and subsequent AML development in children are non-existent. However, the question of whether children can develop leukemia at far lower, environmental levels of benzene remains. The existing scientific evidence relevant to this question will be addressed in this review. While positive findings have been reported, the collective literature does not indicate that exposure to environmental levels of benzene is related to an increased risk of childhood leukemia. Our understanding of this important issue would be strengthened by additional studies that accurately characterize exposures as well as differentiate between the various forms of leukemias observed in children.

Intussusceptions as acute abdomen caused by Burkitt lymphoma: a case report

Introduction

Burkitt's lymphoma is a highly malignant, aggressive and rapidly growing B-cell neoplasm, which has low long-term survival rates. The abdomen is the most frequent onset site of non endemic Burkitt's lymphoma. Symptoms are often misleading and make diagnosis difficult. Ileum intussusception as acute abdomen caused by Burkitt lymphoma is rare.

Case presentation

We are presenting a case of a 16 year-old male with acute abdomen, which three weeks prior initially has been surgically treated for acute appendicitis and Meckel diverticulitis. Following this was a second urgent operation of ileoileal intusussception caused by Burkitt lymphoma. Right extended haemicolectomy was performed.

Conclusion

Affected terminal ileum by Burkitt's lymphoma may mimic clinically acute appendicitis and investigation tools sometimes may not provide proper diagnosis.

Complete resection results in improved survival.

Factors associated with residential mobility in children with leukemia: implications for assigning exposures

PURPOSE

In epidemiologic studies, neighborhood characteristics are often assigned to individuals based on a single residence despite the fact that people frequently move and, for most cancer outcomes, the relevant time-window of exposure is not known. The authors evaluated residential mobility patterns for a population-based series of childhood leukemia cases enrolled in the Northern California Childhood Leukemia Study.

METHODS

Complete residential history from 1 year before birth to date of diagnosis was obtained for 380 cases diagnosed between 1995 and 2002. All residences were assigned U.S. Census block group designations using a geographic information system.

RESULTS

Overall, two-thirds (65.8%) of children had moved between birth and diagnosis, and one-third (34.5%) moved during the first year of life. Approximately 25% of the mothers had moved during the year before the child's birth. Multivariable analysis indicated greater residential mobility to be associated with older age of the child at diagnosis, younger age of the mother at child's birth, and lower household income. Among those who had moved, residential urban/rural status for birth and diagnosis residences changed for about 20% of subjects, and neighborhood socioeconomic status for 35%.

CONCLUSIONS

These results suggest that neighborhood attribute estimates in health studies should account for patterns of residential mobility. Estimates based on a single residential location at a single point in time may lead to different inferences.