Infections and immune factors in cancer: the role of epidemiology

Nationwide Longitudinal Annual Survey of HIV/AIDS Referral Hospitals in Japan From 1999 to 2021: Trend in Non-AIDS-defining Cancers Among Individuals Infected With HIV-1

BACKGROUND

Non-AIDS-defining cancers (NADCs) in patients infected with HIV have recently attracted attention because of the improved survival of this patient population. To obtain accurate data, a longitudinal study is warranted for the nationwide surveillance of the current status and national trend of NADCs in patients infected with HIV in Japan.

SETTING

An annual nationwide surveillance of NADCs in patients infected with HIV-1 in Japan from 1999 to 2021.

METHODS

An annual questionnaire was sent to 378 HIV/AIDS referral hospitals across Japan to collect data (clusters of differentiation 4-positive lymphocytes, time of onset, outcomes, and antiretroviral therapy status) of patients diagnosed with any of the NADCs between 1999 and 2021.

RESULTS

The response and case-capture rates for the questionnaires in 2021 were 37.8% and 81.2%, respectively. The number of reported NADC cases subsequently increased since the beginning of this study. Evaluation of the case counts of NADCs demonstrated a high incidence of lung, colorectal, gastric, and liver cancers as the top 4 cancers. Pancreatic cancer (0.63), lung cancer (0.49), and leukemia (0.49) had the highest mortality rates among the NADCs. Trends of NADCs regarding transmission routes were maintained over the years in male individuals who have sex with male individuals compared with heterosexual male individuals and female individuals.

CONCLUSIONS

We demonstrated an increasing trend in the incidence of NADCs over a period of 23 years in Japan. The current data highlighted the importance of raising awareness regarding cancer management for patients infected with HIV in Japan.

The causal effect and impact of reproductive factors on breast cancer using super learner and targeted maximum likelihood estimation: a case-control study in Fars Province, Iran

OBJECTIVES

The relationship between reproductive factors and breast cancer (BC) risk has been investigated in previous studies. Considering the discrepancies in the results, the aim of this study was to estimate the causal effect of reproductive factors on BC risk in a case-control study using the double robust approach of targeted maximum likelihood estimation.

METHODS

This is a causal reanalysis of a case-control study done between 2005 and 2008 in Shiraz, Iran, in which 787 confirmed BC cases and 928 controls were enrolled. Targeted maximum likelihood estimation along with super Learner were used to analyze the data, and risk ratio (RR), risk difference (RD), andpopulation attributable fraction (PAF) were reported.

RESULTS

Our findings did not support parity and age at the first pregnancy as risk factors for BC. The risk of BC was higher among postmenopausal women (RR = 3.3, 95% confidence interval (CI) = (2.3, 4.6)), women with the age at first marriage ≥20 years (RR = 1.6, 95% CI = (1.3, 2.1)), and the history of oral contraceptive (OC) use (RR = 1.6, 95% CI = (1.3, 2.1)) or breastfeeding duration ≤60 months (RR = 1.8, 95% CI = (1.3, 2.5)). The PAF for menopause status, breastfeeding duration, and OC use were 40.3% (95% CI = 39.5, 40.6), 27.3% (95% CI = 23.1, 30.8) and 24.4% (95% CI = 10.5, 35.5), respectively.

CONCLUSIONS

Postmenopausal women, and women with a higher age at first marriage, shorter duration of breastfeeding, and history of OC use are at the higher risk of BC.

Cohabitation, infection and breast cancer risk

For 50 years, the effect of age at first birth (AFB) has been thought to explain the strong association between breast cancer risk and age at first marriage (AFM), which was first reported in 1926. The independent effects of AFM, AFB and number of sexual partners adjusted for parity and other risk factors were estimated in reanalysis of a large international case-control study conducted in 1979 to 1982 (2274 breast cancers, 18209 controls) by unconditional logistic regression. Respective AFB and AFM breast cancer odds ratios (ORs) for ≥31 years relative to ≤18 years were 3.01 (95% CI 2.44-3.71; P(trend) < .0001) and 3.24 (95% CI 2.62-4.01; P(trend) < .0001) in univariate analyses. Among married parous women, these ORs fell to 1.38 (95% CI 0.98-1.95; P(trend) < .03) for AFB and 1.70 (95% CI 1.17-2.46; P(trend) < .002) for AFM when fitted together in multivariate analysis including other risk factors. A similar adjusted OR for AFM ≥ 31 years relative to ≤18 years was seen among married nulliparous women (OR 1.71, 95% CI 0.98-2.98; P(trend) < .001). AFM (a surrogate for age at starting prolonged cohabitation) is thus strongly associated with breast cancer risk. This suggests an effect of close contact. Identifying the (probably infective) mechanism might lead to effective prevention of breast cancer. The independent effect of AFB is smaller and could be due to residual confounding.

The risk of malignancies in patients receiving hematopoietic stem cell transplantation: a systematic review and meta-analysis

INTRODUCTION

Hematopoietic stem cell transplantation (HSCT) is widely used in the treatment of malignant and non-malignant diseases. Due to advances in the number of survivors of this treatment, the number of survivors is increasing, but the late complications of this therapeutic approach such as secondary cancers have been long term and have not been fully controlled.

METHODS

The present meta-analysis study was performed by considering English-language articles in the databases including Web of Science, Scopus and PubMed. This meta-analysis included cohort studies that reported an incidence of cancer following stem cell transplantation (SCT). Random/fixed effect size meta-analyses were used to standardize the incidence ratio for different cancers.

RESULTS

22 studies that evaluated patients receiving SCT (n = 270,063) were included in the study. The study found 9233 cases of cancer after transplantation. Meta-analysis showed that the risk of cancer after SCT was SIR = 1.66 (95% CI 1.47-1.86). The most common cancers observed in SCT recipients were bone tissue, head and neck cancers, and melanoma, with SIRs of 10.04 (3.48-16.61), 6.35 (4.76-7.93) and 3.52 (2.65-4.39), respectively.

CONCLUSION

The meta-analysis findings showed that the risk of secondary cancers after HSCT was significantly increased in most types of cancers. Consequently, diagnostic tests for common cancers should be included in the screening program of these patients for the prevention and early detection of high-risk cancers.

Religiosity and Beliefs About the Transmission of Cancer, Chemotherapy, and Radiation Through Physical Contact in Saudi Arabia

We examined relationships between religiosity and Saudi cancer patients' beliefs about the spread of cancer, chemotherapy, and radiation therapy through close physical contact. Surveyed were 64 patients seen in university oncology clinics. Assessed were beliefs about the spread of cancer and its treatments, along with religious, demographic, social, psychological, and cancer-related characteristics. Greater religiosity was related to older age, non-Saudi nationality, less anxiety, earlier cancer stage, and greater time since initial diagnosis. Non-significant trends suggested that religious practices were associated with less, but intrinsic religious beliefs with more concern about contagiousness, although the findings were limited by low statistical power.

Nitric oxide functions in stromal cell-derived factor-1-induced cytoskeleton changes and the migration of Jurkat cells

Stromal cell-derived factor-1 (SDF-1) regulates multiple cell signal pathways in a variety of cellular functions, including cell migration, proliferation, survival and angiogenesis. SDF-1-induced chemotaxis is an important step of lymphocyte migration. However, the molecular mechanisms that modulate SDF-1-mediated lymphocyte migration are not well identified. Nitric oxide (NO) has been found to function as a signaling molecule in a number of signaling pathways, including migration. In the present study, the potential role of NO in SDF-1-induced migration and the association between NO and the cytoskeletal changes of Jurkat cells was investigated. The present study demonstrated that Jurkat cells induced the production of NO by SDF-1 stimulation, using Griess reaction method and western blot analysis, and that NO was involved in SDF-1-induced rearrangement and polymerization of the cytoskeleton, using NOS inhibitor L-NMMA. Furthermore, NO was required for the migration of Jurkat cells. The research suggested that NO signaling pathways exerted a critical role in SDF-1-induced cytoskeleton changes and the migration of Jurkat cells. This work provides insight into the migration mechanism of acute lymphoblastic leukemia and provides an effective theoretical basis for therapy strategies for acute lymphoblastic leukemia.

Seasonal trends of diagnosis of childhood malignant diseases and viral prevalence in South Korea

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The present study analyzed the diagnosis pattern of childhood malignant diseases using public health data and viral surveillance data in Korea.

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The number of newly diagnosis showed the highest monthly average in January, and the lowest in September.

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Seasonal trends were apparent in acute myeloid leukemia, Non-Hodgkin’s lymphoma, acute lymphoblastic leukemia and germ cell tumors.

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In winter, significantly more patients were diagnosed with acute lymphoblastic leukemia, acute myeloid leukemia, neuroblastoma, and Hodgkin’s lymphoma than in other seasons.

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There was a temporal correlation with the diagnostic trends of several diseases and the prevalence of recent human parainfluenza virus.

Background

Several studies have reported a seasonal trend in the diagnosis of childhood cancer suggesting seasonal factors such as infection. The present study aimed to analyze the diagnosis pattern of childhood malignant diseases using public health data, and to compare this pattern with seasonal viral infection trends.

Method

Using the open data source of the Health Insurance Review and Assessment Service, we extracted data regarding all patients under 21 years of age and who had any cancer, aplastic anemia or myelodysplastic syndrome between September 2009 and December 2013. The positive detection rates of 11 viruses was collected from the surveillance data of Korea Centers for Disease Control and Prevention, and seasonality analysis were conducted with both data.

Results

In total, 9085 patients were diagnosed with malignant disease during the study period; there were about 175 new cases per month on average. Monthly stacked time series by year showed an apparent seasonal variation with the highest monthly average in January as 236, and the lowest in September as 120. In winter, significantly more patients were diagnosed with acute lymphoblastic leukemia, acute myeloid leukemia, neuroblastoma, and Hodgkin’s lymphoma than in other seasons. There was a temporal correlation with the diagnostic trends of several diseases and the prevalence of recent human parainfluenza virus.

Conclusion

This study tentatively suggests that the diagnosis of childhood malignancy follows a seasonal trend in Korea, and has a possible correlation with viral prevalence in several diseases. Further long-term analysis of epidemiological data is needed to explore possible causality.

Pediatric T-cell acute lymphoblastic leukemia

The most common pediatric malignancy is acute lymphoblastic leukemia (ALL), of which T-cell ALL (T-ALL) comprises 10-15% of cases. T-ALL arises in the thymus from an immature thymocyte as a consequence of a stepwise accumulation of genetic and epigenetic aberrations. Crucial biological processes, such as differentiation, self-renewal capacity, proliferation, and apoptosis, are targeted and deranged by several types of neoplasia-associated genetic alteration, for example, translocations, deletions, and mutations of genes that code for proteins involved in signaling transduction, epigenetic regulation, and transcription. Epigenetically, T-ALL is characterized by gene expression changes caused by hypermethylation of tumor suppressor genes, histone modifications, and miRNA and lncRNA abnormalities. Although some genetic and gene expression patterns have been associated with certain clinical features, such as immunophenotypic subtype and outcome, none has of yet generally been implemented in clinical routine for treatment decisions. The recent advent of massive parallel sequencing technologies has dramatically increased our knowledge of the genetic blueprint of T-ALL, revealing numerous fusion genes as well as novel gene mutations. The challenges now are to integrate all genetic and epigenetic data into a coherent understanding of the pathogenesis of T-ALL and to translate the wealth of information gained in the last few years into clinical use in the form of improved risk stratification and targeted therapies. Here, we provide an overview of pediatric T-ALL with an emphasis on the acquired genetic alterations that result in this disease. © 2016 Wiley Periodicals, Inc.

microRNA-34a-Upregulated Retinoic Acid-Inducible Gene-I Promotes Apoptosis and Delays Cell Cycle Transition in Cervical Cancer Cells

The function of retinoic acid-inducible gene-I (RIG-I) in viral replication is well documented, but its function in carcinogenesis and malignancies as well as relationship with microRNAs (miRNAs) remain poorly understood. miR-34a is an antioncogene in multiple tumors. In our study, RIG-I and miR-34a suppressed cell growth, proliferation, migration, and invasion in cervical cancer cells in vitro. miR-34a was validated as a new regulator of RIG-I by binding to its 3' untranslated region and upregulating its expression level. Furthermore, we revealed that RIG-I and miR-34a enhanced apoptosis, delayed the G1/S/G2 transition of the cell cycle, and inhibited the epithelial-mesenchymal transition process to modulate malignancies in cervical cancer cells. Phenotypic rescue experiments indicated that RIG-I mediates the effects of miR-34a in HeLa and C33A cells. These findings provide new insights into the mechanisms that underlie carcinogenesis and may provide new biomarkers for the diagnosis and therapy of cervical cancer.

Facial transplantation: worth the risks? A look at evolution of indications over the last decade

PURPOSE OF REVIEW

The first face transplant was performed 10 years ago by Dubernard and his team in France. Since then, surgeons have continued to push the frontiers of vascularized composite allotransplantation and broaden the indications for face transplantation. In this review, we summarize some of the recent successes and failures in facial transplantation from the point of view of indications.

RECENT FINDINGS

Recent literature includes case reports on face transplants in sensitized patient, with simultaneous bilateral upper extremity transplants, positive HIV status, and postmalignancy. Additionally, we summarize some of the outcomes of face transplants, including chronic rejection and latent viral infections.

SUMMARY

Facial injuries vary widely, thus candidacy for face transplant should be assessed based on current guidelines, and a case-by-case basis. Although sensitization to donor-specific antigens should not be an absolute contraindication for facial allotransplantation, along with other comorbidities such as positive HIV status, history of malignancy should be evaluated cautiously. Additionally, multiple case studies advice against simultaneous transplantation of multiple vascularized composite allotransplantations. Other considerations include psychological health, social support, and availability for long-term follow-up. Ultimately, face transplant is not simply a surgery; it is a lifelong commitment between a patient and his/her medical team.

Oculocutaneous Albinism and Squamous Cell Carcinoma of the Skin of the Head and Neck in Sub-Saharan Africa

Oculocutaneous albinism which is characterised by impaired melanin biosynthesis is the most common inherited pigmentary disorder of the skin and it is common among Blacks in sub-Saharan Africa. All albinos are at great risk of developing squamous cell carcinoma of sun-exposed skin, and Black albinos in sub-Saharan Africa are at about a 1000-fold higher risk of developing squamous cell carcinoma of the skin than the general population. In Black albinos, skin carcinoma tends to run an aggressive course and is likely to recur after treatment, very probably because the aetiology and predisposing factors have not changed. Prevention or reduction of occurrence of squamous cell carcinoma of the skin in Black albinos might be achieved through educating the population to increase awareness of the harmful effects of exposure to sunlight and at the same time making available effective screening programs for early detection of premalignant and malignant skin lesions in schools and communities and for early treatment.

Race/ethnicity and the risk of childhood leukaemia: a case-control study in California

BACKGROUND

We conducted a large registry-based study in California to investigate the association between race/ethnicity and childhood leukaemia focusing on two subtypes: acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML).

METHODS

We obtained information on 5788 cases and 5788 controls by linking California cancer and birth registries. We evaluated relative risk of childhood leukaemia by race and ethnicity of the child and their parents using conditional logistic regression, with adjustment for potential confounders.

RESULTS

Compared with Whites, Black children had lower risk of ALL (OR=0.54, 95% CI 0.45 to 0.66) as well as children of Black/Asian parents (OR=0.31, 95% CI 0.10 to 0.94). Asian race was associated with increased risk of AML with OR=1.643, 95% CI 1.10 to 2.46 for Asian vs Whites; and OR=1.67, 95% CI 1.04 to 2.70 for Asian/Asian vs White/White. Hispanic ethnicity was associated with increased risk of ALL (OR=1.37, 95% CI 1.22 to 1.52). A gradient in risk of ALL was observed while comparing Hispanic children with both parents Hispanic, one parent Hispanic and non-Hispanic children (p Value for trend <0.0001). The highest risk of ALL was observed for children with a combination of Hispanic ethnicity and White race compared with non-Hispanic whites (OR=1.27, 95% CI 1.12 to 1.44). The lowest risk was observed for non-Hispanic blacks (OR=0.46, 95% CI 0.36 to 0.60). Associations for total childhood leukaemia were similar to ALL.

CONCLUSIONS

Our results confirm that there are ethnic and racial differences in the incidence of childhood leukaemia. These differences indicate that some genetic and/or environmental/cultural factors are involved in aetiology of childhood leukaemia.

Multiple infections and cancer: implications in epidemiology

Approximately 18% of the global cancer burden has been attributed to infectious agents, with estimates ranging from 7% in developed countries to about 22% in developing countries. Chronic infections caused by the hepatitis B and C viruses, human papilloma viruses (HPV), and Helicobacter pylori (H. pylori) are reported to be responsible for approximately 15% of all human cancers. Interestingly, although many of the infectious agents that have been associated with cancer--such as HPV, Epstein-Barr virus (EBV), and H. pylori--are highly prevalent in the world, most infected individuals do not develop cancer but remain lifelong carriers. Malignancies associated with infectious agents may result from prolonged latency as a result of chronic infections. Pathogenic infections are necessary but are not sufficient for cancer initiation or progression. Cancer initiation may require additional cofactors, including secondary infections. Therefore, in patients with chronic infection with one agent, secondary co-infection with another agent may serve as an important co-factor that may cause cancer initiation and progression. Additionally, opportunistic co-infections could significantly inhibit response to cancer treatment and increase cancer mortality. Co-infections are relatively common in areas with a high prevalence of infectious agents, especially in developing countries. These co-infections can cause an imbalance in the host immune system by affecting persistence of and susceptibility to malignant infections. Several articles have been published that focus on infectious agents and cancer. In this article, we discuss the role of infectious agents in malignancies, highlight the role of multiple/co-infections in cancer etiology, and review implications for cancer epidemiology.

Childhood and adult cancers: contrasts and commonalities

Tumours occurring in children differ considerably from those occurring at older ages but exhibit common features. Those occurring in the teenage/young adult (TYA) years represent a transitional mixture of child and adult tumours and pose a considerable challenge for optimal clinical management and service provision. Nevertheless the fundamental processes of malignant change, arising from genetic/epigenetic interaction with environmental exposures, seem to operate across all ages and the entire tumour spectrum. We focus here on the ways in which genotype (and epigenetic modification), growth processes (particularly in utero), and exposure to ionising radiation (in conjunction with genetic susceptibility) affect cancer risk from childhood to adulthood, whether as a primary occurrence, or a second primary tumour following earlier primary occurrence and treatment.

Cancer, immunodeficiency and antiretroviral treatment: results from the Australian HIV Observational Database (AHOD)

OBJECTIVES

The objective of the study was to conduct a within-cohort assessment of risk factors for incident AIDS-defining cancers (ADCs) and non-ADCs (NADCs) within the Australian HIV Observational Database (AHOD).

METHODS

A total of 2181 AHOD registrants were linked to the National AIDS Registry/National HIV Database (NAR/NHD) and the Australian Cancer Registry to identify those with a notified cancer diagnosis. Included in the current analyses were cancers diagnosed after HIV infection. Risk factors for cancers were also assessed using logistic regression methods.

RESULTS

One hundred and thirty-nine cancer cases were diagnosed after HIV infection among 129 patients. More than half the diagnoses (n = 68; 60%) were ADCs, of which 69% were Kaposi's sarcoma and 31% non-Hodgkin's lymphoma. Among the NADCs, the most common cancers were melanoma (n = 10), lung cancer (n = 6), Hodgkin's lymphoma (n = 5) and anal cancer (n = 5). Over a total of 21021 person-years (PY) of follow-up since HIV diagnosis, the overall crude cancer incidence rate for any cancer was 5.09/1000 PY. The overall rate of cancers decreased from 15.9/1000 PY [95% confidence interval (CI) 9.25-25.40/1000 PY] for CD4 counts < 100 cells/μL to 2.4/1000 PY (95% CI 1.62-3.39/1000 PY) for CD4 counts > 350 cells/μL. Lower CD4 cell count and prior AIDS diagnoses were significant predictors for both ADCs and NADCs.

CONCLUSIONS

ADCs remain the predominant cancers in this population, although NADC rates have increased in the more recent time period. Immune deficiency is a risk factor for both ADCs and NADCs.

Enhancement of myeloma development mediated though myeloma cell-Th2 cell interactions after microbial antigen presentation by myeloma cells and DCs

Microbial agents are regarded as a potential cause of tumors, but their direct effects on tumors, such as myeloma, are not well studied. Our studies demonstrated that expression of HLA-DR and CD40 on the myeloma cell membrane surface is upregulated by interferon-γ and/or microbial antigens (Ags). Unlike prior studies, our study showed that Th2 cells cannot promote myeloma growth directly. However, Bacillus Calmette–Guerin Vaccine (BCGV)-specific Th2 cells stimulated by BCGV-loaded dendritic cells (DCs) promoted myeloma clonogenicity directly when the myeloma cells expressed major histocompatibility complex Class-II molecules (MHC-II) and took up BCGV Ag. B-cell lymphoma 6 (Bcl-6) protein expression and the proportion of HLA-DR⁺ or CD40⁺ cells were higher in colonies of Th2 cell-stimulated myeloma cells. Furthermore, anti-HLA-DR or neutralizing CD40 antibody could prevent this increase in Bcl-6 expression and colony number. These results indicate that microbes and microbial Ag-specific Th2 cells may directly impact the biology of myeloma and contribute to tumor progression. Activation may be limited to MHC-II⁺ myeloma cells that retain B cell and stem cell characteristics. Taken together, our data suggest that factors involved in microbial Ag presentation, such as DCs, Th2 cells and so on, are potential targets for myeloma therapeutic intervention.

Evolving models of tumor origin and progression

History of cancer disease models clearly illustrates the evolving nature of these concepts. Since such models undergo continual revisions and additions as a result of underlying medical research, they also tend to reorganize knowledge and allow perceiving previously unseen relationships. Growth of medical thought has been influenced for many centuries by an ancient Hippocratic concept of disease seen as a disturbance in bodily “humors.” True mechanisms of cell and tissue injury started to be elucidated only with the advent of postmortem pathological findings. Concerning cancer, when first disease-producing bacteria were identified in the nineteenth century, also neoplasms were treated as infectious diseases. Foreign organisms were thought to be present inside tumors. However, this hypothesis could not be confirmed by microscopic or histochemical studies. The latter suggested, instead, that tumors were rather formed by abnormal cells. Cancer was then started to be regarded as a disease of cells. This interpretation was radically altered by later developments in genetics which suggested that neoplasms can be treated as genetic diseases as pathologic cellular lesions are caused by mutations in specific genes. More recent models have compared carcinogenesis to evolutionary processes. Due to genetic instability, successive mutations, appearing in cells, lead to selection of cancer cells which feature specific phenotypic traits. The newest data indicate that there may be also a link between cancer and mutated stem cells. The review discusses main concepts of tumor origin forwarded since the beginnings of the nineteenth century.

Orofacial diseases in solid organ and hematopoietic stem cell transplant recipients

OBJECTIVE

Solid organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients are at risk of several diseases, principally attributable to immunosuppression. This global overview of SOT/HSCT-associated orofacial diseases is aimed at providing a practical instrument for the oral healthcare management of SOT/HSCT recipients.

METHODS

Literature search was made through MEDLINE. The associations between orofacial diseases and SOT/HSCT were assessed using observational studies and case series and were classified into 'association', 'no association', and 'unclear association'.

RESULTS

Lip/oral cancers, drug-induced gingival overgrowth (DIGO), infections, including hairy leukoplakia and, less frequently, post-transplantation lymphoproliferative disorders (PTLDs) and oral lichenoid lesions of graft-versus-host disease (GVHD), were associated with SOT. Lip/oral cancers, GVHD, mucositis, DIGO, infections and, less frequently, PTLDs were associated with HSCT. Associations of orofacial granulomatosis-like lesions and oral mucosa-associated lymphoid tissue-type lymphoma with SOT, and of pyogenic granuloma and hairy leukoplakia with HSCT were unclear. Periodontal disease and dental caries were not associated with SOT/HSCT. For none of the local treatments was there a strong evidence of effectiveness.

CONCLUSIONS

Solid organ transplant/HSCT recipients are at risk of orofacial diseases. Adequate management of these patients alleviates local symptoms responsible for impaired eating, helps prevent systemic and lethal complications, and helps where dental healthcare has been neglected.

Inherited variation in pattern recognition receptors and cancer: dangerous liaisons?

The group of pattern recognition receptors includes families of Toll-like receptors, NOD-like receptors, C-type lectin receptors, and RIG-I-like receptors. They are key sensors for a number of infectious agents, some of which are carcinogenic, and they launch an immune response against them. Inherited structural variation in genes encoding these receptors and proteins of their signaling pathways may affect their function, modulating cancer risk and features of cancer progression. Relevant malignancies, valuable gene polymorphisms, prime questions about future directions, and answers to these questions are analyzed in this review. It is possible to suggest that polymorphisms of genes encoding pattern recognition receptors and proteins of their signaling pathways may be associated with almost all cancer types, particularly with those in which carcinogenic infectious agents are responsible for the substantial share of cases (namely gastric cancer, colorectal cancer, liver cancer, cervical cancer, and nasopharyngeal carcinoma). The concept of selection of polymorphisms for further oncogenomic investigation, based on a combination of results from basic and epidemiological studies, is proposed.

Incidence of childhood leukemia in Yogyakarta, Indonesia, 1998-2009

BACKGROUND

In most developing countries, incidence data for childhood cancers are less reliable, because very few population-based registries exist. The aim of this study was to present the epidemiology of childhood leukemia in the Dr. Sardjito Hospital (DSH) region, which catchment area extends beyond the boundaries of the Yogyakarta Special Province (YSP).

PROCEDURE

Health records of children, 0-14 years of age, who were diagnosed with leukemia between January 1998 and December 2009, were reviewed. Diagnosis of leukemia was confirmed by morphological and histochemical examination of marrow samples.

RESULTS

The estimated average annual incidence rate (AAIR) of childhood acute leukemia in DSH was 46.2 per million per year. Interestingly, the annual incidence rate (AIR) of childhood acute leukemia from the catchment area of DSH significantly increased from 35 in 1999 to 70 in 2009 (ANOVA, P = 0.003). The YSP population data, analyzed separately, showed an increase in AIR from 15.7 to 32.9 (ANOVA, P = 0.325) and an AAIR of 28.8. Remarkably, a relatively high frequency (25.5% in DSH and 27.7% in YSP) of children with AML was found in the group of acute leukemias.

CONCLUSION

The DSH incidence calculations may be overestimated due to an underestimation of the population number. Since the population count for YSP is more precise, the data of YSP were used for comparison with developed countries. AAIR of ALL (20.8) is relatively low compared to Western countries (22.4-37.9). The AAIR of AML (8.0) is similar to Western countries (5.0-8.0) resulting a relatively high percentage of AML versus ALL (27.7%) in YSP.

What do we have to know from migrants' past exposures to understand their health status? a life course approach

Empirical findings show that morbidity and mortality risks of migrants can differ considerably from those of populations in the host countries. However, while several explanatory models have been developed, most migrant studies still do not consider explicitly the situation of migrants before migration. Here, we discuss an extended approach to understand migrant health comprising a life course epidemiology perspective.

The incorporation of a life course perspective into a conceptual framework of migrant health enables the consideration of risk factors and disease outcomes over the different life phases of migrants, which is necessary to understand the health situation of migrants and their offspring. Comparison populations need to be carefully selected depending on the study questions under consideration within the life course framework.

Migrant health research will benefit from an approach using a life course perspective. A critique of the theoretical foundations of migrant health research is essential for further developing both the theoretical framework of migrant health and related empirical studies.

Association of polymorphisms in TLR genes and in genes of the Toll-like receptor signaling pathway with cancer risk

Toll-like receptors (TLRs) constitute a family of receptors directly recognizing a wide spectrum of exogenous and endogenous ligands playing the key role in realization of innate and adaptive immune response, and participating in the processes of cell proliferation, survival, apoptosis, angiogenesis, tissue remodeling and repair. Polymorphisms in TLR genes may shift balance between pro- and anti-inflammatory cytokines, modulating the risk of infection, chronic inflammation and cancer. The short list of TLR polymorphisms perspective for oncogenomic investigations can include rs10008492, rs4833103, rs5743815, rs11466657, rs7696175 (TLR1-TLR6-TLR10 gene cluster); rs3804100, rs4696480, -196 - -174 del (Delta22), GT-microsatellite polymorphism (TLR2); 829A/C (TLR3); rs5743836, rs352140 (TLR9). The extended list can additionally include rs4833095 rs5743551, rs5743618 (TLR1); rs5743704, rs62323857, rs1219178642 (TLR2); rs5743305, rs3775291, rs121434431, rs5743316 (TLR3); rs5744168 (TLR5); rs179008 (TLR7); rs3764880, rs2407992 (TLR8); rs352139, rs187084, rs41308230, rs5743844 (TLR9); rs4129009 (TLR10). General reasons for discrepancies between studies are insufficiency of sample size, age/gender/BMI/ethnic/racial differences, differences in prevalence of infectious agent in case and control groups, differences in immune response caused by specific ligand, differences in stratification, methods of diagnostics of cancer or chronic inflammatory conditions, genotyping methods, and chance. Future well-designed studies on large samples should shed light on the significance of TLR polymorphisms for cancer prevention.

Role of NOD1/CARD4 and NOD2/CARD15 gene polymorphisms in cancer etiology

NOD1/CARD4 and NOD2/CARD15 are members of Nod-like receptor family. They are located in cytosol, bind bacterial and viral ligands and play a key role in realization of innate and adaptive immune response, apoptosis, autophagy, and reactive oxygen species generation. Polymorphisms in NOD1/CARD4 and NOD2/CARD15 genes may shift balance between pro- and anti-inflammatory cytokines, modulating the risk of infection, chronic inflammation and cancer. NOD1/CARD4 and NOD2/CARD15 gene polymorphisms may be associated with altered risk of gastric, colorectal, breast, ovarian, prostate, testicular, lung, laryngeal, liver, gallbladder, biliary tract, pancreatic, small bowel, kidney, urinary bladder cancer, skin cancer, nonthyroid endocrine tumors, lymphoma and leukemia. The short list of such polymorphisms perspective for oncogenomic investigations may include rs2006847, rs2066845, rs2066844, rs2066842, ND(1)+32656, rs2075820 whereas rs104895493, rs104895476, rs104895475, rs104895474, rs104895473, rs104895472, rs104895462, rs104895461, rs104895460, rs104895438, rs5743291, rs5743260, rs2076756, rs2066843, Pro371Thr, Ala794Pro, Gln908His, rs72551113, rs72551107, rs6958571, rs2907749, rs2907748, rs2075822, rs2075819, rs2075818 may be added to the extended list. Reasons of discrepancies between different studies include confounding host genetic, bacterial, or environmental factors modulating penetrance of variant allele and affecting risk of condition increasing cancer risk, different bacterial impact in aetiology of such conditions, differences in sample size, clinicopathological characteristics, diagnostics, stratification, genotyping methods, and chance.

Impact of Toll-like receptor 4 polymorphisms on risk of cancer

Toll-like receptor 4 (TLR4) is one of the key immune system effectors playing the main role in recognition of viruses and bacteria. Dysregulation of the TLR4 signaling owing to single nucleotide polymorphisms (SNPs) may alter the ligand binding and balance between pro- and anti-inflammatory cytokines, thereby modulating the risk of chronic inflammation and cancer. TLR4 polymorphisms may be associated with at least nine types of cancer. The most intensively investigating TLR4 polymorphisms are Asp299Gly (rs4986790) and Thr399Ile (rs4986791). It seems to be that Asp299Gly and Thr399Ile are related to increased risk of precancerous gastric lesions, and, possibly, gastric cancer. Thr399Ile also may be connected with gallbladder cancer, and both of these polymorphisms apparently have no impact on risk of prostate cancer. However, the data about many SNPs and their associations with different types of cancer are conflicting, and further large, well-designed, comprehensive studies in various populations are necessary for solution of this problem. The short list of TLR4 SNPs for further investigation may include TLR4_896A/G (Asp299Gly, rs4986790), TLR4_1196C/T (Thr399Ile, rs4986791), Thr135Ala, TLR4_1859 G/A (rs11536858), TLR4_2032T/C (rs10116253), TLR4_2437A/G (rs1927914), TLR4_2856T/C (rs10759932), TLR4_3725 G/C (rs11536889), TLR4_7764 G/A (rs1927911), TLR4_11350G/C, TLR4_11912 G/T (rs2149356), TLR4_16649G/C (rs7873784), and TLR4_17050T/C (rs11536891).

Childhood leukaemia, nuclear sites, and population mixing

The excess of childhood leukaemia (CL) in Seascale, near the Sellafield nuclear reprocessing site in rural NW England, suggested that an epidemic of an underlying infection, to which CL is a rare response, is promoted by marked population mixing (PM) in rural areas, in which the prevalence of susceptibles is higher than average. This hypothesis has been confirmed by 12 studies in non-radiation situations. Of the five established CL excesses near nuclear sites, four are associated with significant PM; in the fifth, the Krummel power station in Germany, the subject has not been thoroughly investigated.

Temporal trends in childhood leukaemia incidence following exposure to radioactive fallout from atmospheric nuclear weapons testing

Notably raised rates of childhood leukaemia incidence have been found near some nuclear installations, in particular Sellafield and Dounreay in the United Kingdom, but risk assessments have concluded that the radiation doses estimated to have been received by children or in utero as a result of operations at these installations are much too small to account for the reported increases in incidence. This has led to speculation that the risk of childhood leukaemia arising from internal exposure to radiation following the intake of radioactive material released from nuclear facilities has been substantially underestimated. The radionuclides discharged from many nuclear installations are similar to those released into the global environment by atmospheric nuclear weapons testing, which was at its height in the late-1950s and early-1960s. Measurements of anthropogenic radionuclides in members of the general public resident in the vicinity of Sellafield and Dounreay have found levels that do not differ greatly from those in persons living remote from nuclear installations that are due to ubiquitous exposure to the radioactive debris of nuclear weapons testing. Therefore, if the leukaemia risk to children resulting from deposition within the body of radioactive material discharged from nuclear facilities has been grossly underestimated, then a pronounced excess of childhood leukaemia would have been expected as a consequence of the short period of intense atmospheric weapons testing. We have examined childhood leukaemia incidence in 11 large-scale cancer registries in three continents for which data were available at least as early as 1962. We found no evidence of a wave of excess cases corresponding to the peak of radioactive fallout from atmospheric weapons testing. The absence of a discernible increase in the incidence of childhood leukaemia following the period of maximum exposure to the radioactive debris of this testing weighs heavily against the suggestion that conventional methods are seriously in error when assessing the risk of childhood leukaemia from exposure to man-made radionuclides released from nuclear installations.

Adult acute lymphoblastic leukemia: concepts and strategies

Acute lymphoblastic leukemia (ALL), a clonal expansion of hematopoietic blasts, is a highly heterogeneous disease comprising many entities for which distinct treatment strategies are pursued. Although ALL is a success story in pediatric oncology, results in adults lag behind those in children. An expansion of new drugs, more reliable immunologic and molecular techniques for the assessment of minimal residual disease, and efforts at more precise risk stratification are generating new aspects of adult ALL therapy. For this review, the authors summarized pertinent and recent literature on ALL biology and therapy, and they discuss current strategies and potential implications of novel approaches to the management of adult ALL. Cancer 2010. (c) 2010 American Cancer Society.

Viral epigenomes in human tumorigenesis

Viruses are associated with 15-20% of human cancers worldwide. In the last century, many studies were directed towards elucidating the molecular mechanisms and genetic alterations by which viruses cause cancer. The importance of epigenetics in the regulation of gene expression has prompted the investigation of virus and host interactions not only at the genetic level but also at the epigenetic level. In this study, we summarize the published epigenetic information relating to the genomes of viruses directly or indirectly associated with the establishment of tumorigenic processes. We also review aspects such as viral replication and latency associated with epigenetic changes and summarize what is known about epigenetic alterations in host genomes and the implications of these for the tumoral process. The advances made in characterizing epigenetic features in cancer-causing viruses have improved our understanding of their functional mechanisms. Knowledge of the epigenetic changes that occur in the genome of these viruses should provide us with markers for following cancer progression, as well as new tools for cancer therapy.

Might salicylate exert benefits against childhood cancer?

Childhood cancers are a broad range of diseases. Research on the chemopreventive potential of non-steroidal anti-inflammatory drugs, such as aspirin (acetylsalicylate) has yet to be fully directed towards childhood cancers. A prima facie hypothesis on salicylate and childhood cancer would therefore be based on several factors. Firstly, salicylate inhibits the production of inflammatory prostaglandins, which have been shown to stimulate the growth of cancer cells. Secondly, salicylate inhibits the growth of cancer cells in pre-clinical models. Thirdly, salicylate is a natural component of fruits and vegetables so it is consumed within the diet. Further research, of which some possibilities are identified, is recommended.

Cancer and viral infections in immunocompromised individuals

Over the last 30 years, the increasing use of organ and stem cell transplantation and the AIDS epidemic have led to the realization that some, but not all, human cancers occur more frequently in immunosuppressed individuals. With the notable exception of non-melanoma skin cancer (NMSC), most tumors that show strongly increased incidence rates in both transplant recipients and AIDS patients have been found to have a viral etiology. Among these are Kaposi sarcoma, diffuse large cell B-cell lymphoma, cervical cancer, liver cancer, Merkel cell carcinoma and a subset of Hodgkin's disease. A viral etiology for NMSC, i.e., beta- and gamma-subtypes of human papillomavirus, has been suggested and investigated for many years, but remains controversial. In addition, the moderately increased incidence rates of several other cancers in immunosuppressed individuals (e.g., Vajdic and van Leeuwen, Int J Cancer, in press) could indicate that additional infectious causes for at least some human cancers remain to be discovered. The controversy surrounding the role of cutaneous papillomavirus subtypes in the pathogenesis of NMSC illustrates the difficulties encountered when weighing the epidemiological and molecular biology evidence arguing for an involvement of highly prevalent viruses in certain types of cancer.

Cancer patterns among children of Turkish descent in Germany: a study at the German Childhood Cancer Registry

Background

Cancer risks of migrants might differ from risks of the indigenous population due to differences in socioeconomic status, life style, or genetic factors. The aim of this study was to investigate cancer patterns among children of Turkish descent in Germany.

Methods

We identified cases with Turkish names (as a proxy of Turkish descent) among the 37,259 cases of childhood cancer registered in the German Childhood Cancer Registry (GCCR) during 1980–2005. As it is not possible to obtain reference population data for children of Turkish descent, the distribution of cancer diagnoses was compared between cases of Turkish descent and all remaining (mainly German) cases in the registry, using proportional cancer incidence ratios (PCIRs).

Results

The overall distribution of cancer diagnoses was similar in the two groups. The PCIRs in three diagnosis groups were increased for cases of Turkish descent: acute non-lymphocytic leukaemia (PCIR 1.23; CI (95%) 1.02–1.47), Hodgkin's disease (1.34; 1.13–1.59) and Non-Hodgkin/Burkitt lymphoma (1.19; 1.02–1.39). Age, sex, and period of diagnosis showed no influence on the distribution of diagnoses.

Conclusion

No major differences were found in cancer patterns among cases of Turkish descent compared to all other cases in the GCCR. Slightly higher proportions of systemic malignant diseases indicate that analytical studies involving migrants may help investigating the causes of such cancers.

Acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia, a malignant disorder of lymphoid progenitor cells, affects both children and adults, with peak prevalence between the ages of 2 and 5 years. Steady progress in development of effective treatments has led to a cure rate of more than 80% in children, creating opportunities for innovative approaches that would preserve past gains in leukaemia-free survival while reducing the toxic side-effects of current intensive regimens. Advances in our understanding of the pathobiology of acute lymphoblastic leukaemia, fuelled by emerging molecular technologies, suggest that drugs specifically targeting the genetic defects of leukaemic cells could revolutionise management of this disease. Meanwhile, studies are underway to ascertain the precise events that take place in the genesis of acute lymphoblastic leukaemia, to enhance the clinical application of known risk factors and antileukaemic agents, and to identify treatment regimens that might boost the generally low cure rates in adults and subgroups of children with high-risk leukaemia.

Childhood cancer epidemiology in low-income countries

Global studies of childhood cancer provide clues to cancer etiology, facilitate prevention and early diagnosis, identify biologic differences, improve survival rates in low-income countries (LIC) by facilitating quality improvement initiatives, and improve outcomes in high-income countries (HIC) through studies of tumor biology and collaborative clinical trials. Incidence rates of cancer differ between various ethnic groups within a single country and between various countries with similar ethnic compositions. Such differences may be the result of genetic predisposition, early or delayed exposure to infectious diseases, and other environmental factors. The reported incidence of childhood leukemia is lower in LIC than in more prosperous countries. Registration of childhood leukemia requires recognition of symptoms, rapid access to primary and tertiary medical care (a pediatric cancer unit), a correct diagnosis, and a data management infrastructure. In LIC, where these services are lacking, some children with leukemia may die before diagnosis and registration. In this environment, epidemiologic studies would seem to be an unaffordable luxury, but in reality represent a key element for progress. Hospital-based registries are both feasible and essential in LIC, and can be developed using available training programs for data managers and the free online Pediatric Oncology Networked Data Base (www.POND4kids.org), which allows collection, analysis, and sharing of data.

Evidence of population mixing based on the geographical distribution of childhood leukemia in Ohio

BACKGROUND

This ecologic study examined the geographic distribution of childhood leukemias in Ohio, 1996-2000, among children aged 0-19 for evidence that population mixing may be a factor.

PROCEDURE

(1) State incidence rates were compared to Surveillance, Epidemiology and End Results (SEER) rates for each year and for the 5-year period, 1996-2000; (2) incidence rates for each of Ohio's 88 counties were compared to statewide rates; and (3) county incidence rates were compared based on population density, population growth, and rural/urban locale. SEER*Stat version 5.0 was used to derive age-specific and 0-19 age-adjusted rates. Expected values, standardized incidence ratios (SIRs), and Poisson P-values were calculated with Excel using the indirect method of standardization.

RESULTS

Of the 585 cases, 73.3% were acute lymphocytic leukemia (ALL), 16.6% acute myelogenous leukemia (AML), 3.2% acute monocytic leukemia (AMoL), and 2.6% chronic myelogenous leukemia (CML). Rates for total leukemia burden were significantly below national levels for all races (P = 0.00001), likely due to poor ascertainment of cases. Yearly incidence rates for 1996-2000 were stable for ALL and AML; CML rates declined over the period. Based on 2000 Census and intercensal population estimates for 1996-2000, statistically higher rates for ALL were noted for counties experiencing >10% population change 1990-2000 (P < 0.05), especially for ages 1-4 (P < 0.03) in counties with 10-20% growth. Counties 67.9-99.2% urban experienced fewer than expected cases of AML + AMoL (P < 0.06).

CONCLUSION

Data support Kinlen's theory of population mixing and warrant further studies in Ohio, the US and other countries.

Allergy and risk of childhood leukaemia: results from the UKCCS

We investigated the relationship between childhood leukaemia and preceding history of allergy. A nationwide case-control study of childhood cancers was conducted in the United Kingdom with population-based sampling of cases (n = 839) and controls (n = 1,337), matched on age, sex and region of residence. Information about clinically diagnosed allergies was obtained from primary care records. More than a third of subjects had at least one allergy diagnosed prior to leukaemia diagnosis (cases) or pseudo-diagnosis (controls). For both total acute lymphoblastic leukaemia (ALL) and common-ALL/precursor B-cell ALL (c-ALL), a history of eczema was associated with a 30% significant reduction in risk: the odds ratios (OR) and 95% confidence intervals (CI) were 0.70 (0.51-0.97) and 0.68 (0.48-0.98), respectively. Similar associations were observed for hayfever (OR = 0.47; 95% CI: 0.26-0.85 and OR = 0.62; 95% CI: 0.33-1.16 for ALL and c-ALL, respectively). No such patterns were seen either for asthma and ALL, or for any allergy and acute myeloid leukaemia. A comparative analysis of primary care records with parents recall of allergy revealed only moderate agreement with contemporaneous clinical diagnoses for both cases and controls--confirming the unreliability of parental report at interview. Our finding of a reciprocal relationship between allergy and ALL in children is compatible with the hypothesis that a dysregulated immune response is a critical determinant of childhood ALL.

Childhood leukaemia and infectious exposure: a report from the United Kingdom Childhood Cancer Study (UKCCS)

Data from a national case-control study are used to explore the relationships between childhood leukaemia, infant infection and three markers of infectious exposure - birth order, infant-activity group attendance and area-based deprivation. Amongst controls, clinically diagnosed infection in the first year varied little with birth order and infant-activity group attendance - with 4 in 5 children having at least one infection, and each child averaging around 2.9 (2.8-3.0). Amongst cases of acute lymphoblastic leukaemia (ALL), the levels of infection increased as the indices of infectious exposure increased - for example, odds ratios associated with at least one infection in the first year being 0.9 (95% confidence interval (CI): 0.6-1.4) for birth order one and 1.6 (95% CI: 1.1-2.2) for birth order two or more. By contrast, interview data were misleading, with mothers - particularly case mothers - consistently under-reporting. We conclude that the findings based on clinical data, combined with the markers of infectious exposure, confirm the observation that immune dysregulation among children who develop ALL is detectable from an early age.

Risk of cancer following immunosuppression in organ transplant recipients and in HIV-positive individuals in southern Europe

This investigation highlighted the risk of cancer in 8074 HIV-infected people and in 2875 transplant recipients in Italy and France. Observed and expected numbers of cancer were compared through sex- and age-standardised incidence ratios (SIRs) and 95% confidence intervals (CIs). After 15 years of follow-up, the cumulative probability of cancer was 14.7% in transplant recipients and 13.3% in HIV-positives. The SIRs for all cancers were 9.8 in HIV-positives and 2.2 in transplants. Kaposi's sarcoma (SIR=451 in HIV-positives, 125 in transplants) and non-Hodgkin lymphoma (SIR=62 and 11.1, respectively) were the most common cancers. A significantly increased SIR for liver cancer also emerged in both groups. The risk of lung cancer was significantly elevated in heart transplant recipients (SIR=2.8), and of borderline statistical significance in HIV-positive people (95% CI:0.9-2.8). Immune depression entails a two-fold increased overall risk of cancers, mainly related to cancers associated with a viral aetiology.

Incidence of cancers in people with HIV/AIDS compared with immunosuppressed transplant recipients: a meta-analysis

BACKGROUND

Only a few types of cancer are recognised as being directly related to immune deficiency in people with HIV/AIDS. Large population-based studies in transplant recipients have shown that a wider range of cancers could be associated with immune deficiency. Our aim was to compare cancer incidence in population-based cohort studies of people with HIV/AIDS and people immunosuppressed after solid organ transplantation.

METHODS

Two investigators independently identified eligible studies through searches of PubMed and reference lists. Random-effects meta-analyses of log standardised incidence ratios (SIRs) were calculated by type of cancer for both immune deficient populations.

FINDINGS

Seven studies of people with HIV/AIDS (n=444,172) and five of transplant recipients (n=31 977) were included. For 20 of the 28 types of cancer examined, there was a significantly increased incidence in both populations. Most of these were cancers with a known infectious cause, including all three types of AIDS-defining cancer, all HPV-related cancers, as well as Hodgkin's lymphoma (HIV/AIDS meta-analysis SIR 11.03, 95% CI 8.43-14.4; transplant 3.89, 2.42-6.26), liver cancer (HIV/AIDS 5.22, 3.32-8.20; transplant 2.13, 1.16-3.91), and stomach cancer (HIV/AIDS 1.90, 1.53-2.36; transplant 2.04, 1.49-2.79). Most common epithelial cancers did not occur at increased rates.

INTERPRETATION

The similarity of the pattern of increased risk of cancer in the two populations suggests that it is immune deficiency, rather than other risk factors for cancer, that is responsible for the increased risk. Infection-related cancer will probably become an increasingly important complication of long-term HIV infection.

Genetic polymorphisms and disease prevention

Building upon the resources of traditional epidemiology, molecular epidemiology has extended our understanding that disease risk varies based not only upon acquired factors (e.g., exposures, behaviors, demographics), but also as a function of inherited factors (e.g., genetic polymorphisms). Individual susceptibility to cancer is influenced by polymorphisms in phase I enzymes (e.g., activation), phase 2 enzymes (e.g., detoxification), defects in the repair of DNA damage and other cancer susceptibility genes. Because tobacco use and nutrition represent behaviors/exposures which account for a significant number of cancer cases and deaths, these two factors are used to illustrate the relationship between genetic polymorphisms and disease prevention. Susceptibility to the health risks of smoking appears to be influenced by genetic factors that impact initiation, dependence, and nicotine metabolism. Nutrient metabolism also involves polymorphic enzyme pathways and gene-nutrient interactions may influence cancer risk. While the discipline of molecular epidemiology continues to face methodologic challenges related to the need to study large numbers of subjects, current knowledge can be applied to prevention activities. Genetic polymorphisms, and other molecular markers, can be used to develop clinical prevention studies targeted to unique subsets of persons at the highest risk of developing disease. Knowledge about the relationships between polymorphisms and disease outcomes can also be used for reinforcing healthy lifestyles, motivating positive behavior changes, helping to target medical therapy, and aiding in better focusing surveillance activities.

Infectious etiologies of childhood leukemia: plausibility and challenges to proof

Infections as well as environmental exposures are proposed determinants of childhood acute lymphoblastic leukemia (ALL), particularly common precursor B-cell ALL (cALL). Lines of investigation test hypotheses that cALL is a rarer result of common infection, that it results from uncommon infection, or that it ensues from abnormal immune development; perhaps it requires a preceding prenatal or early childhood insult. Ideally, studies should document that particular infections precede leukemiA and induce malignant transformation. However, limited detection studies have not directly linked specific human or nonhuman infectious agents with ALL or cALL. Primarily based on surrogate markers of infectious exposure, indirect evidence from ecologic and epidemiologic studies varies widely, but some suggest that infancy or early childhood infectious exposures might protect against childhood ALL or cALL. Several others suggest that maternal infection during pregnancy might increase risk or that certain breast-feeding practices decrease risk. To date, evidence cannot confirm or refute whether at least one infection induces or is a major co-factor for developing ALL or cALL, or perhaps actually protects against disease. Differences in methodology and populations studied may explain some inconsistencies. Other challenges to proof include the likely time lag between infection and diagnosis, the ubiquity of many infections, the influence of age at infection, and the limitations in laboratory assays; small numbers of cases, inaccurate background leukemia rates, and difficulty tracking mobile populations further affect duster investigations. Nevertheless, existing evidence partially supports plausibility and warrants further investigation into potential infectious determinants of ALL and cALL, particularly in the context of multifactorial or complex systems.

Early infection and risk of childhood brain tumors (Canada)

OBJECTIVE

Up to 15% of human cancers can be attributed to infections. Currently there are no known associations between infective agents and childhood brain tumors. We explored childhood brain tumor risk associated with a variety of indicators of infection during gestation and childhood.

METHODS

Two hundred and seventy-two cases of childhood brain tumor diagnosed in children less then 15 years of age in the province of Quebec between 1980 and 1999 were included in the study. An equal number of sex and age matched population based controls were recruited from family allowance or provincial health insurance files. Conditional logistic regression was used to estimate the risk of developing childhood brain tumors associated with self-reported exposure to infection.

RESULTS

Childhood brain tumor risk was weakly to moderately elevated after maternal reported exposure to several indicators of infection: use of antibiotics during gestation (OR = 1.7, 95% CI = 0.8-3.6) or childhood (OR = 1.4, 95% CI = 0.7-2.9), removal of tonsils, adenoids or appendix (OR = 1.2, 95% CI = 0.6-2.4), having siblings (OR = 1.4, 95% CI = 0.9-2.3), and being at least second born (OR = 1.7, 95% CI = 1.2-2.4). Moreover, childhood brain tumor risk was reduced for some subjects who were breastfed or attended daycare for more than 1 year. Risk varied by sex, age at diagnosis and tumor type.

CONCLUSION

Childhood brain tumor risk may be associated with exposure to infective agents.

Immunosuppression and Cancer: A Comparison of Risks in Recipients of Organ Transplants and in HIV-Positive Individuals

The comparison of cancers occurring excessively among HIV-infected and transplanted individuals may help to elucidate the relationship between immune surveillance, viral infections, and cancer. A longitudinal study was conducted on 2002 HIV-infected Italian subjects, 6072 HIV-infected French individuals, and 2878 Italian recipients of solid organ transplants. Standardized incidence ratios (SIR) and 95% confidence intervals (CI) were computed to quantify the risk for cancer, compared with the French and Italian general populations. The SIRs for all cancers were 9.8 (95% CI: 9.0-10.6) for HIV-infected individuals versus 2.2 (95% CI: 1.9-2.5) for transplant recipients. In both groups, most of the excess risk was attributable to virus-related cancers, such as Kaposi's sarcoma (KS; SIR = 451 in HIV-positive individuals, 125 in transplant recipients), non-Hodgkin's lymphoma (NHL; SIR = 62.1 and 11.1, respectively), and liver cancer (SIR = 9.4 and 4.1, respectively). Significantly increased SIRs for anal cancer and Hodgkin's lymphoma were found only among HIV-positive individuals. Among women younger than 40 years of age, a more than 10-fold increase in cervical cancer risk was found in both groups. Among HIV-infected individuals treatment with highly active antiretroviral therapies drastically reduced SIRs for KS and NHL only. These results show that HIV-infected individuals and transplant recipients share a similar pattern of cancer risk, largely due to virus-related cancers.

Childhood acute lymphocytic leukemia and perspectives on risk assessment of early-life stage exposures

Recognition that children are a potentially susceptible subpopulation has led to the development of child-specific sensitivity factors. Establishing reliable sensitivity factors in support of risk assessment of early-life stage exposures can be aided by evaluating studies that enhance our understanding both of the biological basis of disease processes and the potential role of environmental exposures in disease etiology. For these reasons, we evaluated childhood acute lymphocytic leukemia (ALL) studies from the point of view of mechanism and etiology. ALL is the most common form of childhood cancer proposed to result from a prenatal primary event and a postnatal second event. This multi-stage model is supported by the observation that chromosomal translocations/fusion genes (e.g., TEL-AML1) involved in producing ALL are detected at birth (prenatal event), and a postnatal event (e.g., TEL deletion) is required for disease manifestation. It appears that a proportion of ALL cases are the result of environmental exposures, in which case preconceptional, prenatal, and postnatal stages are likely to be critical exposure windows. To this end, we recognized postnatal infection-related risk factors as potential candidates associated with the ALL second event. Additionally, we discuss use of ALL-associated fusion genes and genetic polymorphisms, together or separately, as indicators of ALL susceptibility and increased risk. The possibility of using fusion genes alone as biomarkers of response is also discussed because they can serve as predictors of key events in the development of a mode of action (a sequence of key events, starting with interaction of an agent with a cell, ultimately resulting in cancer formation) for particular environmental exposures. Furthermore, we discuss use of an initiated animal model for ALL, namely transgenic mice with TEL-AML1 expression, for exploring mechanisms by which different classes of environmental exposures could be involved in inducing the postnatal step in ALL formation.