What causes Hodgkin's disease in children?

Classic Hodgkin lymphoma in young people

Classic Hodgkin lymphoma (CHL) is a unique form of lymphoid cancer featuring a heterogeneous tumor microenvironment and a relative paucity of malignant Hodgkin and Reed-Sternberg (HRS) cells with characteristic phenotype. Younger individuals (children, adolescents and young adults) are affected as often as the elderly, producing a peculiar bimodal age-incidence profile that has generated immense interest in this disease and its origins. Decades of epidemiological investigations have documented the populations most susceptible and identified multiple risk factors that can be broadly categorized as either biological or environmental in nature. Most risk factors result in overt immunodeficiency or confer more subtle alterations to baseline health, physiology or immune function. Epstein Barr virus, however, is both a risk factor and well-established driver of lymphomagenesis in a significant subset of cases. Epigenetic changes, along with the accumulation of somatic driver mutations and cytogenetic abnormalities are required for the malignant transformation of germinal center-experienced HRS cell precursors. Chromosomal instability and the influence of endogenous mutational processes are critical in this regard, by impacting genes involved in key signaling pathways that promote the survival and proliferation of HRS cells and their escape from immune destruction. Here we review the principal features, known risk factors and lymphomagenic mechanisms relevant to newly diagnosed CHL, with an emphasis on those most applicable to young people.

Clinical Characteristics and Treatment Outcomes in Children, Adolescents, and Young-adults with Hodgkin's Lymphoma: a KPHOG Lymphoma Working-party, Multicenter, Retrospective Study

BACKGROUND

Hodgkin's lymphoma (HL) constitutes 10%-20% of all malignant lymphomas and has a high cure rate (5-year survival, around 90%). Recently, interest has increased concerning preventing secondary complications (secondary cancer, endocrine disorders) in long-term survivors. We aimed to study the epidemiologic features and therapeutic outcomes of HL in children, adolescents, and young adults in Korea.

METHODS

We performed a multicenter, retrospective study of 224 patients aged < 25 years diagnosed with HL at 22 participating institutes in Korea from January 2007 to August 2016.

RESULTS

A higher percentage of males was diagnosed at a younger age. Nodular sclerosis histopathological HL subtype was most common, followed by mixed cellularity subtype. Eighty-one (36.2%), 101 (45.1%), and 42 (18.8%) patients were classified into low, intermediate, and high-risk groups, respectively. Doxorubicin, bleomycin, vinblastine, dacarbazine was the most common protocol (n = 102, 45.5%). Event-free survival rate was 86.0% ± 2.4%, while five-year overall survival (OS) rate was 96.1% ± 1.4%: 98.7% ± 1.3%, 97.7% ± 1.6%, and 86.5% ± 5.6% in the low, intermediate, and high-risk groups, respectively (P = 0.021). Five-year OS was worse in patients with B-symptoms, stage IV disease, high-risk, splenic involvement, extra-nodal lymphoma, and elevated lactate dehydrogenase level. In multivariate analysis, B-symptoms and extra-nodal involvement were prognostic factors for poor OS. Late complications of endocrine disorders and secondary malignancy were observed in 17 and 6 patients, respectively.

CONCLUSION

This is the first study on the epidemiology and treatment outcomes of HL in children, adolescents, and young adults in Korea. Future prospective studies are indicated to develop therapies that minimize treatment toxicity while maximizing cure rates in children, adolescents, and young adults with HL.

Cancer of childhood in sub-Saharan Africa

Measurement of incidence rates of childhood cancer in Africa is difficult. The study 'Cancer of Childhood in sub Saharan Africa' brings together results from 16 population-based registries which, as members of the African Cancer Registry Network (AFCRN), have been evaluated as achieving adequate coverage of their target population. The cancers are classified according to the third revision of the International Classification of Childhood Cancer (ICCC-3) and recorded rates in Africa are compared with those in childhood populations in the UK, France, and the USA. It is clear that, in many centres, lack of adequate diagnostic and treatment facilities leads to under-diagnosis (and enumeration) of leukaemias and brain cancers. However, for several childhood cancers, incidence rates in Africa are higher than those in high-income countries. This applies to infection-related cancers such as Kaposi sarcoma, Burkitt lymphoma, Hodgkin lymphoma and hepatocellular carcinoma, and also to two common embryonal cancers - retinoblastoma and nephroblastoma. These (and other) observations are unlikely to be artefact, and are of considerable interest when considering possible aetiological factors, including ethnic differences in risk (and hence genetic/familial antecedents). The data reported are the most extensive so far available on the incidence of cancer in sub Saharan Africa, and clearly indicate the need for more resources to be devoted to cancer registration, especially in the childhood age range, as part of an overall programme to improve the availability of diagnosis and treatment of this group of cancers, many of which have-potentially-an excellent prognosis.

[Analysis of small areas of pediatric cancer in the municipality of Murcia (Spain)]

INTRODUCTION

Occasionally, primary care pediatricians notice the presence of small clusters of pediatric cancer (PC), but are often frustrated by the findings after statistical analysis. The study of small areas in spatial epidemiology has led to advances in identifying clusters and the environmental risk factors involved. The purpose of this study was to describe the PC incidence and the spatial distribution at the minimum level of disaggregation possible in Murcia, presenting the first urban municipality map of PC in Spain.

MATERIALS AND METHODS

A population-based descriptive study was conducted on the PC cases diagnosed in children younger than 15 years, between 1998 and 2013 in the municipality of Murcia. Cases were classified by sex, age group, and tumor type. Coordinates of home addresses at the time of diagnosis were assigned to each case, and spatial and spatio-temporal analyses were carried out at the level of census tracts, using FleXScan and SatScan.

RESULTS

A total of 155 cases of PC were diagnosed during this period. The overall incidence of PC (138/10(6) of children under the age of 15) and the incidence for individual tumor types were within the expected ranges for Europe. A spatio-temporal cluster of Hodgkin lymphoma was identified.

CONCLUSIONS

Small area analysis of PC cases may be a useful tool for the identification of PC clusters, which would allow for the generation of hypotheses regarding disease etiology, as well as developing urban models for environmental surveillance of PC.

Is birth weight associated with childhood lymphoma? A meta-analysis

Several risk factors have been identified for childhood lymphomas. The purpose of this meta-analysis was to synthesize current evidence regarding the association between birth weight with primarily the risk for non-Hodgkin lymphoma (NHL), given its similarity to acute lymphoblastic leukemia, Hodgkin lymphoma (HL) and any category of lymphoma. Two cohort (278,751 children) and seven case-control studies (2,660 cases and 69,274 controls) were included. Effects estimates regarding NHL, HL and any lymphoma were appropriately pooled using fixed or random effects model in two separate analyses: specifically, high was compared to normal or any birth weight. Similarly, low was compared to normal or any birth weight. No statistically significant association was found between high birth weight, as compared to normal birth weight, and risk for NHL plus Burkitt lymphoma (OR = 1.17, 95% CI = 0.76-1.80, random effects), HL (OR = 0.94, 95% CI = 0.64-1.38, fixed effects) or any plus Burkitt lymphoma (OR = 1.09, 95% CI = 0.76-1.56, fixed effects). A null association emerged when low was compared with normal birth weight for NHL plus Burkitt lymphoma (OR = 1.07, 95% CI = 0.71-1.62, random effects), HL (OR = 0.94, 95% CI = 0.54-1.65, fixed effects) or any plus Burkitt lymphoma (OR = 1.02, 95% CI = 0.79-1.33, fixed effects). Accordingly, no association was found when high or low birth weight was compared to any birth weight. Although current evidence suggests no association, birth weight might be a too crude indicator to reveal a genuine association of fetal growth with specific lymphoma categories; hence, there is an emerging need for use of more elaborate proxies, at least those accounting for gestational week.

Maternal smoking during pregnancy and childhood lymphoma: a meta-analysis

Results from epidemiological studies exploring the association between childhood lymphoma and maternal smoking during pregnancy have been contradictory. This meta-analysis included all published cohort (n = 2) and case-control (n = 10) articles; among the latter, the data of the Greek Nationwide Registry for Childhood Hematological Malignancies study were updated to include all recently available cases (-2008). Odds ratios (ORs), relative risks and hazard ratios were appropriately pooled in three separate analyses concerning non-Hodgkin lymphoma (NHL, n = 1,072 cases), Hodgkin lymphoma (HL, n = 538 cases) and any lymphoma (n = 1,591 cases), according to data availability in the included studies. An additional metaregression analysis was conducted to explore dose-response relationships. A statistically significant association between maternal smoking (any vs. no) during pregnancy and risk for childhood NHL was observed (OR = 1.22, 95% confidence interval, CI: 1.03-1.45, fixed effects model), whereas the risk for childhood HL was not statistically significant (OR = 0.90, 95% CI: 0.66-1.21, fixed effects model). The analysis on any lymphoma did not reach statistical significance (OR = 1.10, 95% CI = 0.96-1.27, fixed effects model), possibly because of the case-mix of NHL to HL. No dose-response association was revealed in the metaregression analysis. In conclusion, this meta-analysis points to a modest increase in the risk for childhood NHL, but not HL, among children born by mothers smoking during pregnancy. Further investigation of dose-response phenomena in the NHL association, however, warrants accumulation of additional data.

Parental educational attainment as an indicator of socioeconomic status and risk of childhood cancers

Background:

Little has been reported on socioeconomic (SES) patterns of risk for most forms of childhood cancer.

Methods:

Population-based case–control data from epidemiological studies of childhood cancer conducted in five US states were pooled and associations of maternal, paternal and household educational attainment with childhood cancers were analysed. Odds ratios (ORs) and 95% confidence intervals were estimated using logistic regression, controlling for confounders.

Results:

Although there was no association with parental education for the majority of cancers evaluated, there was an indication of a positive association with lower education for Hodgkin's and Burkitt's lymphoma and Wilm's tumour, with the ORs ranging from 1.5 to >3.0 times that of more educated parents. A possible protective effect was seen for lower parental education and astrocytoma and hepatoblastoma, with ORs reduced by 30 to 40%.

Conclusions:

These study results should be viewed as exploratory because of the broad nature of the SES assessment, but they give some indication that childhood cancer studies might benefit from a more thorough assessment of SES.

The results of Hodgkin lymphoma treatment in children in the period 1997-2006

In this paper we present the study of chemotherapy and radiotherapy treatment success in children suffering from Hodgkin's disease (HD) that were treated at Hematology-oncology Department of Pediatric Clinic in Sarajevo. In retrospective study we followed all patients with HD aged 0-15 who were diagnosed with and treated for HD at Pediatric Clinic in Sarajevo over the last 10 years (1st of January 1997 - 31st of December 2006). Until 2000 we used combination of chemotherapy and radiotherapy according to UKCCSG HD 9201 treatment protocol, and after the year 2000 protocol UKCCSG HD 2000 (ChlVPP / ABVD) was applied. The total number of the treated children 33. There were 17 boys (51,51 %) and 16 girls (48,49 %). In 10 patients (30,3 %) we found II A stage of HD, in 4 (12,1 %) II B stage of HD, in 6 children (18,8 %) stage III A, in 4 children (12,1 %) stage III B, in 4 children (12,1 %) stage IV A and in 5 (15,1 %) stage IV B. In 7 patients (21,2 %) relapse occurred, which demanded more aggressive chemotherapeutic treatment and radiotherapy too; while for 4 patients (12,1 %) in combination with bone marrow transplantation. Three patients (9,0 %) died. There are 30 children (91,0 %) who are alive and in either 1st or 2nd remission phase of HD. Secondary malignancies did not occur in any of the patients. Although many patients (58,1%) were diagnosed in an advanced stage of illness (III and IV) the results of HD therapy at Pediatric Clinic in Sarajevo are comparable to those in other European centers.

Sun exposure, birth weight, and childhood lymphomas: a case control study in Greece

OBJECTIVES

To explore whether the inverse association of sun exposure with non Hodgkin lymphoma among adults is also evident among the childhood population and test the specificity of the relation by contrasting the findings to those for Hodgkin lymphoma.

METHODS

A total of 87 cases of childhood (0-14 years) with non Hodgkin lymphoma and 71 with Hodgkin lymphoma, diagnosed in Greece through the national network of childhood Hematology-Oncology Units, during a 7-year period, along with 164 age- and gender-matched control children were enrolled in the study. The guardians of all eligible children were interviewed in person on the basis of a structured questionnaire covering socio-demographic, anthropometric, and perinatal characteristics. Average time of sunbathing per year at a seaside resort was used as a proxy variable of exposure to sun controlling for use of sun protection measures.

RESULTS

The estimated incidence of 10.2 cases per 1,000,000 children-years {95% Confidence Intervals (CI), 8.4-12.1} for NHL during the study period in Greece is around the average figure in countries of the European Union. There was an inverse association of sun exposure with Non Hodgkin lymphoma, namely, for an increment of 15 days of sunbathing at seaside resorts children had almost 40% lower risk (Odds Ratio: 0.60, 95% CI: 0.43-0.83), whereas no such association was evident for Hodgkin lymphoma. The risk for non Hodgkin lymphoma has been found to be statistically and significantly higher in birth weight (Odds ratio: 1.42 and 95% CI, 1.04-1.92, for every 500 g increment), whereas there was no substantial indication that maternal education or maternal smoking during the child's life were important risk factors for the disease.

CONCLUSIONS

This is the first study to provide epidemiological evidence that increased sun exposure of children may also be associated with a decreased risk of developing childhood non Hodgkin, but not Hodgkin lymphoma.

Pathobiology of Classical Hodgkin Lymphoma

The World Health Organization has acknowledged the malignant nature of classical Hodgkin lymphoma (cHL), which encompasses four histological subtypes. The diagnosis of cHL is based on the detection of malignant Hodgkin and Reed-Sternberg cells (HRSC) confirmed by immunophenotyping and the detection of growth patterns specific to each histological subtype. The pathologic HRSC arise from germinal center or immediate postgerminal cells that lack detectable immunoglobulin/B-cell antigen receptor expression, with a consequent loss of B-cell identity; very few cHL cases are of T-cell origin. To escape apoptosis, which normally occurs in B cells with nonfunctioning antigen receptor machinery, HRSC develop concurrent antiapoptotic mechanisms by activation of nuclear factor-kappaB or are rescued by Epstein-Barr virus infection. HRSC are characterized by a variable and inconstant immunophenotype, with a remarkable loss of lineage-specific cell antigens and expression of antigens of other cell lineages. The master plan of B-cell identity in HRSC is disturbed not only at the immunoglobulin expression level, but also at the transcriptional factor level. HRSC are further characterized by profound cell cycle deregulation with futile replication, multinucleation and poly- and aneuploidy. Here, we review pathobiological aspects of cHL with respect to lymphomagenesis and routine diagnostics.

Hodgkin's disease incidence and survival in European children and adolescents (1978-1997): report from the Automated Cancer Information System project

This paper reports the geographical patterns and time trends of incidence and survival of Hodgkin's disease (HD) in children and adolescents in Europe over the period 1978-1997. Data on 4230 HD cases were gathered from 62 paediatric or general cancer registries in 19 European countries by the Automated Cancer Information System (ACCIS). European annual incidence rates in 1988-1997 were estimated at 5.8 per million in children (world age-standardised) and at 29.7 per million in adolescents, with higher rates in the East and South. Incidence rates increased steeply with age, while the male predominance, marked for the youngest children, vanished in the highest age groups. Over the period 1978-1997 incidence rates increased in age groups 10-14 years (+1% per year) and 15-19 years (+3.5% per year), mainly due to the nodular sclerosis subtype. Age and sex distribution of cases remained unchanged with time. The overall 5-year survival rate was higher in children (93%, 95% confidence interval (CI) 92-94) than in adolescents (89% (95% CI 87-91)) for the period 1988-1997. Five-year survival increased significantly in all regions from 87% to 93% in children and from 80% to 88% in adolescents between 1978-1982 and 1993-1997. In future, detailed documentation of cases in the cancer registries with respect to standardised diagnostic subtypes, stage of extension, and treatments, will help to refine interpretation of international and temporal variations in incidence and survival.

Breast-feeding duration and childhood acute leukemia and lymphomas in a sample of Turkish children

OBJECTIVES

Whether breast-feeding is associated with decreased incidence of the lymphoid malignancies in children is uncertain. We evaluated childhood acute leukemia and lymphoma in relation to duration of breast-feeding.

METHODS

We investigated this issue in a case-control study comprising 137 patients, aged 1 to 16 years, with acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), Hodgkin or non-Hodgkin lymphoma, in addition to 146 controls matched for age and sex.

RESULTS

The median duration of breast-feeding among patients was shorter than that of controls (10 vs 12 months). Patients with ALL and AML had shorter mean breast-feeding duration compared with healthy children (P = 0.001 and P < 0.001, respectively). The shortest mean breast-feeding duration was noted in the children with AML. Breast-feeding for a duration of 0 to 6 months, when compared with feeding of longer than 6 months, was associated with increased odds ratios (ORs) for ALL [OR = 2.44, 95% confidence interval (CI) = 1.17-5.10], AML (OR = 6.67, 95% CI = 1.32-33.69), Hodgkin lymphoma (OR = 3.33, 95% CI = 0.60-18.54), non-Hodgkin lymphoma (OR = 1.90, 95% CI = 0.68-5.34) and overall (OR = 2.54, 95% CI = 1.51-4.26).

CONCLUSIONS

Our findings suggest that breast-feeding of more than 6 months is protective against childhood lymphoid malignancies, especially for AML and ALL.

Incidence and Characteristics of Childhood Hodgkin’s Lymphoma in Greece: A Nationwide Study (Greece)

OBJECTIVES

To estimate the incidence and epidemiological profile of childhood (0-14 years) Hodgkin's lymphoma in Greece derived by the network of childhood Hematology-Oncology departments on the basis of all 95 newly diagnosed cases during a seven-year period.

METHODS

Seventy-one of these cases were individually age and gender matched to an equal number of controls.

RESULTS

The incidence of childhood Hodgkin Lymphoma reached a relatively high figure of 7.8 per million children-years, with an age distribution (2.2 for children 0-4; 6.3 for those 5-9 and 13.9 for those 10-14-years-old) and male to female ratio (1.7:1) similar to that reported from other cancer registries. Childhood Hodgkin's lymphoma was more common among children living in less crowded quarters (odds ratio (OR): 6.5 and 95% confidence intervals (95% CI): 1.4-30.7), among those who have changed residence 60 to 18 months before the onset of the index disease (OR: 4.4, and 95% CI = 1.4-14.0), among those whose families owned a cat (OR: 5.5, 95% CI = 1.2-25.6) but not among those whose families owned a dog and marginally more common, among those with a history of infectious mononucleosis (OR: 5.0, 95% CI = 0.6-42.8).

CONCLUSIONS

Our results point to infectious agent(s) as playing an etiological role but do not allow discrimination among the delayed establishment of the herd immunity hypothesis, the population mixing hypothesis or that invoking transmission of the agent(s) from the non-human reservoir.

Treatment of pediatric Hodgkin disease avoiding radiotherapy: excellent outcome with the Rotterdam-HD-84-protocol

BACKGROUND

To reduce radiotherapy (XRT) induced toxicity of treatment of children with Hodgkin disease (HD) while maintaining a high cure rate, we introduced a risk-adapted protocol consisting of chemotherapy (CT) alone in 1984.

PROCEDURE

The outcome of 46 children treated for HD from 1984 until 2000 according to the Rotterdam-HD-84-protocol was determined. Children with stage I-IIA disease (n = 23), were treated with six courses of epirubicin, bleomycin, vinblastine, and dacarbazine (EBVD). Children with stage IIB-IV disease (n = 23), were treated with three to five alternating cycles of EBVD and mechlorethamine, vincristine, procarbazine, and prednisone (MOPP).

RESULTS

At a median follow-up time of 8.6 years (range 2.6-18.3 years), the 10-year overall survival (OS) is 95% and the event-free survival (EFS) 91%. In 5/46 patients XRT was administered because of residual mediastinal mass. Four children relapsed, two of them died. Up until now only one patient developed hypothyroidism; no symptomatic cardiac or pulmonary dysfunction, no second malignancy has been diagnosed.

CONCLUSIONS

Risk-adapted treatment consisting of CT alone is highly efficacious for children with HD and toxicity is low. XRT was administered in only a small minority of children with HD. CT should be the first choice for HD in children and XRT should preferably be used for those with refractory or histologically proven residual disease or relapse.

Epidemiology of Hodgkin's disease and non-Hodgkin's lymphoma

This review considers in detail the descriptive and aetiological epidemiology of Hodgkin's disease and non-Hodgkin's lymphoma (NHL), with attention to histological subcategories when the literature allows. The aetiology of Hodgkin's disease remains only partially understood. There is evidence that Epstein-Barr virus (EBV) may be involved in the causation of some cases, and clinical immune deficiency is a risk factor for a few, but the evidence is not entirely consistent and other factors may also be important in causing the EBV-associated cases of Hodgkin's disease. The cause of EBV-unassociated cases remains obscure. For NHL, although it has been shown that some cases are related to immune deficiency and chronic antigenic stimulation, and especially to EBV in the context of immune deficiency, the causation of the majority of cases remains unknown. The increasing incidence of NHL, other than that related to AIDS, is also essentially unexplained. Epidemiological investigation of the aetiology of NHL and Hodgkin's disease is making steady progress, however, and there remain leads to be followed that may result in a better understanding and hence prevention.

Cancer incidence in adolescents and young adults in the United States, 1992-1997

PURPOSE

To examine cancer incidence patterns among adolescents and young adults in the United States.

METHODS

Cancer incidence data from 26 population-based central cancer registries for 1992-1997 were used. Individual cancers were grouped into specific diagnostic groups and subgroups using an integrated classification scheme. The integrated scheme was developed for this study and was based on the most commonly used schemes in population-based epidemiologic studies: Surveillance, Epidemiology, and End Results Program's site groups, International Classification of Childhood Cancer, and International Agency for Research on Cancer's Histological Groups for Comparative Studies. Percent distributions and age-specific incidence rates per million population were computed for adolescents (aged 15-19 years) and young adults (aged 20-24 years) by gender.

RESULTS

The data for 26,010 cancer cases were examined. Among 15-19-year-olds, the five most common cancers were Hodgkin's disease, leukemia, cancer in the brain and other nervous system, bone cancer, and non-Hodgkin's disease. Among 20-24-year-olds, the five most common cancers were Hodgkin's disease, testicular cancer, thyroid cancer, melanoma of the skin, and leukemia. The proportions and rates of the histologic subtypes for most of the common cancers changed with advancing age. For example, among 15-19-year-olds, acute lymphocytic leukemia accounted for approximately 60% of leukemias in males and 50% in females. Among 20-24-year-olds, however, the corresponding percentages of acute lymphocytic leukemia were 37% in males and 31% in females. For ovarian cancer, the germ cell tumor was the most common subtype (54.6% of all ovarian cancers) among 15-19-year-olds. In contrast, ovarian carcinoma was the predominant subtype (70.4%) among 20-24-year-olds. For both age groups, the incidence rates of nodular Hodgkin's disease, melanoma of the skin, and thyroid cancer were significantly greater in females than in males.

CONCLUSIONS

Cancer incidence patterns among adolescents and young adults are distinctive. In these age groups, a transition from predominantly pediatric histologic subtypes to adult subtypes was observed for Hodgkin's disease, leukemia, ovarian cancer, and soft tissue sarcoma. Gender differences were found for Hodgkin's disease, melanoma of the skin, and thyroid cancer.

Childhood cancer in relation to infections in the community during pregnancy and around the time of birth

In a retrospective cohort study of 404,106 live births in the northern region of England, 1975-1986, we investigated whether higher levels of community infections during the mother's pregnancy and in early life were risk factors for cancer, by diagnostic group (leukaemia and non-Hodgkin's lymphoma, Hodgkin's disease, brain/spinal tumours, neuroblastoma, other tumours), diagnosed 1975-2001 under age 15 years. Logistic regression was used to relate risk to measures of community infections (measles, respiratory and other infections) in 3 prenatal and 2 postnatal quarters. There was an increased risk of Hodgkin's disease among children exposed around birth to higher levels of measles (odds ratio for trend = 2.3, 95% confidence interval 1.3-4.2, p = 0.01). For other diagnostic groups, there was no consistent evidence of an association between risk and exposure to infections. Although the significant association observed for Hodgkin's disease may be a chance finding, consequent to multiple hypothesis testing or the ecologic nature of the study, it is consistent with other recent epidemiologic results suggesting that the risk of Hodgkin's disease may be associated with exposure to infections.

Childhood solid tumours in relation to population mixing around the time of birth

In a retrospective cohort study of 673 787 live births in the Northern Region of England, 1975-1994, we investigated whether a higher level of population mixing around birth was a risk factor for solid tumours, by diagnostic group (Hodgkin's disease, brain and spinal tumours, neuroblastoma, other solid tumours), diagnosed during 1975-2001 under age 15 years. Logistic regression was used to relate risk to population mixing, based on (i) all movers and (ii) incomers from outside the region. Both ward and county district level analyses were performed. There was a decreased risk of brain and spinal tumours with increasing population mixing based on incomers from outside the region (OR for trend across three categories=0.79, 95% CI: 0.66-0.95, P=0.01 in the ward level analysis). Although this may be because of chance, it is consistent with a role of exposure to infection and immunological response in the aetiology of these tumours. For other tumour groups, there was no consistent evidence of an association between risk and population mixing.

Is classical Hodgkin's disease indeed a single entity?

We present a retrospective clinicopathological study on the significance of the histologic type of classical Hodgkin's disease (HD) in a cohort of patients from southern Israel. This was performed to critically evaluate the generally accepted view that classical HD is a single clinicopathological entity and the resultant impression that its segregation into four different histologic types remains essential only for the pathologist in his diagnostic endeavor. We confirmed the existence of a uniform response of nodular sclerosis (NS), and mixed cellularity-lymphocyte depletion (MC-LD)-HD to treatment, consideration being given to other classical prognostic factors. We also accept the fact that histological type is not a significant independent factor in terms of survival. Our findings, however, do suggest that NS-HD, on the one hand, and MC-LD-HD, on the other, are distinct biologic entities. Cases of NS differ significantly from those of MC-LD-HD with regard to sex and age distribution, and in the expression of several antigens and gene products, including sialylated-CD15, CD30, LMP1 and the p53 and mdm-2 gene products.

Identification of the neoplastically transformed cells in Marek's disease herpesvirus-induced lymphomas: recognition by the monoclonal antibody AV37

Understanding the interactions between herpesviruses and their host cells and also the interactions between neoplastically transformed cells and the host immune system is fundamental to understanding the mechanisms of herpesvirus oncology. However, this has been difficult as no animal models of herpesvirus-induced oncogenesis in the natural host exist in which neoplastically transformed cells are also definitively identified and may be studied in vivo. Marek's disease (MD) herpesvirus (MDV) of poultry, although a recognized natural oncogenic virus causing T-cell lymphomas, is no exception. In this work, we identify for the first time the neoplastically transformed cells in MD as the CD4(+) major histocompatibility complex (MHC) class I(hi), MHC class II(hi), interleukin-2 receptor alpha-chain-positive, CD28(lo/-), phosphoprotein 38-negative (pp38(-)), glycoprotein B-negative (gB(-)), alphabeta T-cell-receptor-positive (TCR(+)) cells which uniquely overexpress a novel host-encoded extracellular antigen that is also expressed by MDV-transformed cell lines and recognized by the monoclonal antibody (MAb) AV37. Normal uninfected leukocytes and MD lymphoma cells were isolated directly ex vivo and examined by flow cytometry with MAb recognizing AV37, known leukocyte antigens, and MDV antigens pp38 and gB. CD28 mRNA was examined by PCR. Cell cycle distribution and in vitro survival were compared for each lymphoma cell population. We demonstrate for the first time that the antigen recognized by AV37 is expressed at very low levels by small minorities of uninfected leukocytes, whereas particular MD lymphoma cells uniquely express extremely high levels of the AV37 antigen; the AV37(hi) MD lymphoma cells fulfill the accepted criteria for neoplastic transformation in vivo (protection from cell death despite hyperproliferation, presence in all MD lymphomas, and not supportive of MDV production); the lymphoma environment is essential for AV37(+) MD lymphoma cell survival; pp38 is an antigen expressed during MDV-productive infection and is not expressed by neoplastically transformed cells in vivo; AV37(+) MD lymphoma cells have the putative immune evasion mechanism of CD28 down-regulation; AV37(hi) peripheral blood leukocytes appear early after MDV infection in both MD-resistant and -susceptible chickens; and analysis of TCR variable beta chain gene family expression suggests that MD lymphomas have polyclonal origins. Identification of the neoplastically transformed cells in MD facilitates a detailed understanding of MD pathogenesis and also improves the utility of MD as a general model for herpesvirus oncology.

Dorothy Reed and Hodgkin's disease: a reflection after a century

It has now been 100 years since Dorothy Reed, at the age of 28, wrote her paper on Hodgkin's disease. Her biography reveals the difficult lives of women entering the hitherto male-dominated field of medicine, let alone medical research. Her historic paper on Hodgkin's disease is remarkable for its brilliant observations and concise scientific reasoning. Nevertheless, she was told that as a woman she could not hope for a career as an academic pathologist. After marriage to Charles Elwood Mendenhall, Professor of Physics at the University of Wisconsin and after giving birth to four children, the second part of her career began. Motivated by the loss of her firstborn, she began a study of infant mortality, an interest that lasted throughout her career. In 1926, Mendenhall undertook a survey comparing infant and maternal mortality rates in Denmark and the United States. This influential study concluded that American mortality rates were higher because of unnecessary interference in the natural process of childbirth and recommended the education of midwives follow the Danish model. In 1937, her efforts were rewarded when Madison, WI received recognition for having the lowest infant mortality of any city in the United States. Reading Reed's paper on Hodgkin's disease, we see that her observations go far beyond a description of a specific cell. Her presentation of macroscopic and microscopic features is remarkable for the distinction between "young" and "old" growths: Reed saw Hodgkin's disease as a process, rather than the spreading of a cancer. She was the first to note that those most commonly affected are boys or young adults, especially those whose general health before the disease had been excellent. She was also the first to note anergy to tuberculin. Dorothy Reed defined Hodgkin's disease in relation to tuberculosis, described its pathologic features, and offered comments on its pathogenesis, epidemiology, and immunology that still deserve to be discussed.

Hodgkin's disease in Asians: incidence patterns and risk factors in population-based data

Hodgkin's disease (HD) has been reported to be rare in Asians. Data sparseness has hindered studies exploring the relative contributions of environment and heredity to HD etiology, and individual risk factors have never been studied in an Asian population. With the most recent, uniformly collected population-based data from the US and Asia, we compared HD incidence rates in Chinese, Japanese, Filipinos, and Asian Indians in the US and in Asia. HD incidence rates were quite low in all Asian subgroups, but approximately double in US Asians as in native Asians. In both, rates were lower for Japanese and Chinese than for Filipinos and Asian Indians. A modest young-adult rate peak occurred for most US Asian groups, but not for any population in Asia. In data from a population-based case-control study of HD in San Francisco area women, young-adult Asian cases, like young-adult cases of other racial/ethnic groups, had childhood social environments indicative of less early contact with children. Given environmental and lifestyle differences between the US and Asia, the consistently low rates of HD in Asians suggest genetic resistance to disease development, possibly associated with HLA type. International and inter-ethnic differences, and risk factor patterns in case-control data, implicate environmental influences in the etiology of HD.

Epstein-Barr virus and cancers of the head and neck

Denis Burkitt pioneered the association of viruses and cancer in humans with his observations of lymphomatous tumors in children in equatorial Africa. The Epstein-Barr virus (EBV), a human B lymphotrophic herpes virus, is strongly associated with undifferentiated carcinoma of the nasopharynx and African-type Burkitt's lymphoma. More recently, an association of this virus with other epithelial neoplasms, lymphomas, and immunodeficiency-related malignant and nonmalignant conditions has been reported. Since many of these tumors are rare, much of the information is based on sporadic reports and relatively small series of patients. The purpose of this report is to review the literature and examine the growing association of EBV with various head and neck malignancies.

Air pollution from traffic at the residence of children with cancer

The hypothesis that exposure to traffic-related air pollution increases the risk of developing cancer during childhood was investigated. The authors enrolled 1,989 children reported to the Danish Cancer Registry with a diagnosis of leukemia, tumor of the central nervous system, or malignant lymphoma during 1968-1991 and 5,506 control children selected at random from the entire childhood population. The residential histories of the children were traced from 9 months before birth until the time of diagnosis of the cases and a similar period for the controls. For each of the 18,440 identified addresses, information on traffic and the configuration of streets and buildings was collected. Average concentrations of benzene and nitrogen dioxide (indicators of traffic-related air pollution) were calculated for the relevant period, and exposures to air pollution during pregnancy and during childhood were calculated separately. The risks of leukemia, central nervous system tumors, and all selected cancers combined were not linked to exposure to benzene or nitrogen dioxide during either period. The risk of lymphomas increased by 25% (p for trend = 0.06) and 51% (p for trend = 0.05) for a doubling of the concentration of benzene and nitrogen dioxide, respectively, during the pregnancy. The association was restricted to Hodgkin's disease.