Cancer incidence in Denmark following exposure to poliovirus vaccine contaminated with simian virus 40

Diffuse Pleural Mesothelioma: Advances in Molecular Pathogenesis, Diagnosis, and Treatment

Diffuse pleural mesothelioma (DPM) is a highly aggressive malignant neoplasm arising from the mesothelial cells lining the pleural surfaces. While DPM is a well-recognized disease linked to asbestos exposure, recent advances have expanded our understanding of molecular pathogenesis and transformed our clinical practice. This comprehensive review explores the current concepts and emerging trends in DPM, including risk factors, pathobiology, histologic subtyping, and therapeutic management, with an emphasis on a multidisciplinary approach to this complex disease.

Recent Advances in Vaccine Technology and Design

If up until three years ago, infectious diseases were a lesser concern when compared to non-communicable diseases in Western countries, the ongoing pandemic has reminded us that things are not so clean-cut [...].

Vaccination and the Risk of Childhood Cancer-A Systematic Review and Meta-Analysis

INTRODUCTION

Infections may play a role in the etiology of childhood cancer and immunizations may be protective because vaccinations stimulate the immune system. Observational studies reported inconsistent associations between vaccination and risk of childhood cancer. Since a synthesis of the evidence is lacking, we conducted a meta-analysis stratified by histological and site-specific cancer.

METHODS

We performed a systematic review (CRD42020148579) following PRISMA guidelines and searched for literature in MEDLINE, Embase, and the Science Citation Index databases. We identified in three literature databases 7,594 different articles of which 35 met the inclusion criteria allowing for 27 analyses of 11 cancer outcomes after exposure to nine different types of vaccinations. We calculated summary odds ratios (ORs) and 95% confidence intervals (CIs) using random effects models.

RESULTS

We observed four inverse associations between childhood leukemia and certain vaccines as well as the number of vaccinations: OR 0.49 (95% CI = 0.32 to 0.74) for leukemia death after bacillus Calmette-Guérin vaccination; OR 0.76 (95% CI = 0.65 to 0.90) for acute lymphoblastic leukemia after Haemophilus influenzae type b vaccination; OR 0.57 (95% CI = 0.36 to 0.88) for leukemia; and OR 0.62 (95% CI = 0.46 to 0.85) for acute lymphoblastic leukemia after three or more vaccinations of any type. All other conducted analyses did not show any associations.

DISCUSSION

The results are consistent with the hypothesis that vaccinations reduce the risk of childhood leukemia. However, the robustness and validity of these results is limited due to the small number, substantial heterogeneity, and methodological limitations of available studies.

'A matter of commonsense': the Coventry poliomyelitis epidemic 1957 and the British public

In 1956, the British Ministry of Health instituted a vaccination programme against poliomyelitis, but run into myriad supply and administrative issues. When Coventry experienced an epidemic in 1957, it came to symbolise these problems. Throughout, it was claimed that the government lacked 'common sense'. This article explores how and why 'common sense' was used as a rhetorical weapon in the debates over policy at the local and national level. While those claiming 'common sense' were often at odds with medical and administrative authorities, the arguments were often informed by deeply held beliefs about vaccination and disease.

Cancer risk associated with receipt of vaccines contaminated with simian virus 40: epidemiologic research

Simian virus (SV)40 was an accidental contaminant of poliovirus vaccines used widely in the USA and other countries in 1955-1962. Exposure to SV40 via contaminated vaccines has led to concern as SV40 causes cancer in laboratory animals. In addition, some laboratories, although not all, have detected SV40 DNA in human tumors including mesothelioma, certain brain tumors, osteosarcoma and non-Hodgkin's lymphoma. This article reviews the data regarding contamination of poliovirus vaccines with SV40 and summarizes the results from epidemiologic studies of vaccine recipients. Long-term follow-up studies have not revealed recipients of SV40-contaminated poliovirus vaccines to be at an increased risk for cancer. Thus, these studies are somewhat reassuring and indicate that either SV40 does not readily infect humans or, following infection, does not cause cancer. Recognizing that the history of SV40 contamination of vaccines highlights an inherent risk of contamination of vaccines with adventitious agents, the Institute of Medicine recently called for the development of a comprehensive US plan to prevent vaccine contamination and respond to potential contamination events when they arise.

Patterns of polyomavirus SV40 infections and associated cancers in humans: a model

A model is described that predicts patterns of polyomavirus SV40 infections and associated cancers in humans. The model proposes that SV40 infections were established in humans primarily by exposure to contaminated oral poliovaccines and that infections persist today in geographic regions where poor sanitation or living conditions allow maintenance of infections transmitted by a fecal/urine-oral route. Predictions from the model include that SV40 infections and virus-associated malignancies will be restricted geographically and demographically and that in developed countries, such as the US, SV40 prevalence rates will be generally very low. The model highlights the importance of selection of populations for investigations of SV40 human infections. This model can explain inconsistencies in the published literature of SV40 infections in humans and can guide the design of future studies.

Prevalence of polyomaviruses and links with human diseases

The simian virus 40 and murine polyomaviruses were shown to be DNA tumor viruses in their natural hosts and/or heterologous experimental hosts in the mid-20th Century. The first two human polyomaviruses, the BK polyomavirus and JC polyomavirus, were discovered in 1971 and were shown to induce severe disease in immunocompromised patients, but their involvement in human cancers is still a matter for debate. The discovery of a polyomavirus associated with Merkel cell carcinoma (Merkel cell polyomavirus) in 2008 resulted in a renewed interest in the Polyomaviridae family, leading to the discovery of new human polyomaviruses. This review addresses the involvement of the nine human polyomaviruses and simian virus 40 in human diseases, with a particular focus on their prevalence and the humoral response directed against structural antigens in the general population and in subjects presenting specific diseases.

Ependymal tumors

Ependymomas represent a heterogeneous group of glial tumors whose biological behavior depends on various histological, molecular, and clinical variables. The scope of this chapter is to review the clinical and histo-logical features as well as the molecular genetics of ependymomas with special emphasis on their influence on tumor recurrence and prognosis. Furthermore, potential molecular targets for therapy are outlined.

Brain tumor epidemiology: consensus from the Brain Tumor Epidemiology Consortium

Epidemiologists in the Brain Tumor Epidemiology Consortium (BTEC) have prioritized areas for further research. Although many risk factors have been examined over the past several decades, there are few consistent findings, possibly because of small sample sizes in individual studies and differences between studies in patients, tumor types, and methods of classification. Individual studies generally have lacked samples of sufficient size to examine interactions. A major priority based on available evidence and technologies includes expanding research in genetics and molecular epidemiology of brain tumors. BTEC has taken an active role in promoting understudied groups, such as pediatric brain tumors; the etiology of rare glioma subtypes, such as oligodendroglioma; and meningioma, which, although it is not uncommon, has only recently been registered systematically in the United States. There also is a pressing need for more researchers, especially junior investigators, to study brain tumor epidemiology. However, relatively poor funding for brain tumor research has made it difficult to encourage careers in this area. In this report, BTEC epidemiologists reviewed the group's consensus on the current state of scientific findings, and they present a consensus on research priorities to identify which important areas the science should move to address.

Pathogenesis of malignant pleural mesothelioma and the role of environmental and genetic factors

BACKGROUND

Malignant pleural mesothelioma (MPM) is a rare and aggressive tumor for which no effective therapy exists despite the discovery of many possible molecular and genetic targets. The late stage of MPM diagnosis and the long latency that exist between some exposures and diagnosis have made it difficult to comprehensively evaluate the role of risk factors and their downstream molecular effects.

METHODS

This manuscript is a review of current literature about the pathogenesis of malignant mesothelioma. In this overview, current published studies concerning pathogenesis of malignant mesothelioma are reviewed, with insights into its etiology and pathogenesis. We searched pubmed using the following subjects: mesothelioma, radiation, genetics, pediatric malignant mesothelioma, SV40 virus, and growth factors. We selected 350 valuable articles of which 152 sources were used to complete this review.

CONCLUSION

Many risk factors for MPM development have been recognized including environmental exposures, genetic susceptibility, viral contamination, and radiation. In this review, we discuss the current molecular and genetic contributors to MPM pathogenesis and the risk factors associated with these carcinogenic processes.

Pathogenesis of malignant pleural mesothelioma and the role of environmental and genetic factors

Malignant pleural mesothelioma (MPM) is a rare, aggressive tumor for which no effective therapy exists despite the discovery of many possible molecular and genetic targets. Many risk factors for MPM development have been recognized including environmental exposures, genetic susceptibility, viral contamination, and radiation. However, the late stage of MPM diagnosis and the long latency that exists between some exposures and diagnosis have made it difficult to comprehensively evaluate the role of risk factors and their downstream molecular effects. In this review, we discuss the current molecular and genetic contributors in MPM pathogenesis and the risk factors associated with these carcinogenic processes.

Simian virus 40 and mesothelioma in Great Britain

BACKGROUND

Simian virus 40 (SV40) is a DNA virus that has been shown capable of infecting and transforming cells in various species. Laboratory studies have suggested that inoculation with SV40 is associated with various types of cancer, including mesothelioma.

AIMS

To test the hypothesis, via an ecological analysis, that exposure to SV40 via contaminated polio vaccines is a risk factor for mesothelioma in humans.

METHODS

Mesothelioma mortality rates in Great Britain for two birth cohorts likely to have been exposed to SV40 via poliovirus vaccination were compared with a birth cohort likely to be largely unexposed.

RESULTS

There was some evidence for both males (P < 0.05) and females (P < 0.05) that the mesothelioma mortality rates were higher in the first exposed cohort: rate ratio (RR) = 2.4 [95% CI (confidence interval) 1.2-5.0] and RR = 3.7 (95% CI 1.0-14). However, in the second exposed cohort, mortality rates were elevated in females only, and the evidence was slightly less convincing (P = 0.055).

CONCLUSION

Although the results for females show a reduction in the mesothelioma mortality rate coinciding with the introduction of the SV40-free Sabin polio vaccine, the absence of a similar result in males and of a priori biological evidence of a sex-specific SV40 effect, makes chance the most plausible interpretation of these findings.

Absence of SV40 antibodies or DNA fragments in prediagnostic mesothelioma serum samples

The rhesus monkey virus Simian Virus 40 (SV40) is a member of the polyomavirus family. It was introduced inadvertently to human populations through contaminated polio vaccine during the years 1956-1963, can induce experimental tumors in animals and transform human cells in culture. SV40 DNA has been identified in mesothelioma and other human tumors in some but not all studies. We tested prediagnostic sera from 49 mesothelioma cases and 147 matched controls for antibodies against the viral capsid protein VP1 and the large T antigen of SV40 and of the closely related human polyomaviruses BK and JC, and for SV40 DNA. Cases and controls were identified among donors to the Janus Serum Bank, which was linked to the Cancer Registry of Norway. Antibodies were analyzed by recently developed multiplex serology based on recombinantly expressed fusions of glutathione-S transferase with viral proteins as antigens combined with fluorescent bead technology. BKV and JCV specific antibodies cross- reactive with SV40 were preabsorbed with the respective VP1 proteins. Sera showing SV40 reactivity after preabsorption with BKV and JCV VP1 were further analyzed in SV40 neutralization assays. SV40 DNA was analyzed by SV40 specific polymerase chain reactions. The odds ratio for being a case when tested positive for SV40 VP1 in the antibody capture assay was 1.5 (95% CI 0.6-3.7) and 2.0 (95% CI 0.6-7.0) when only strongly reactive sera where counted as positive. Although some sera could neutralize SV40, preabsorption with BKV and JCV VP1 showed for all such sera that this neutralizing activity was due to cross-reacting antibodies and did not represent truly SV40-specific antibodies. No viral DNA was found in the sera. No significant association between SV40 antibody response in prediagnostic sera and risk of mesothelioma was seen.

The non-Hodgkin lymphomas: a review of the epidemiologic literature

The non-Hodgkin lymphomas (NHL) are a heterogeneous group of B-cell and T-cell neoplasms that arise primarily in the lymph nodes. NHL incidence rates in the US doubled between about 1970 and 1990, and stabilized during the 1990s. NHL accounts for approximately 3.4% of cancer deaths in the US. Although some of the observed patterns in NHL have been related to HIV/AIDS, these conditions cannot fully explain the magnitude of the changes; neither do changes in classification systems nor improved diagnostic capabilities. Studies of occupational and environmental exposures (e.g., pesticides, solvents) have produced no consistent pattern of significant positive associations. Inverse associations with ultraviolet radiation exposure and alcohol and fish intake, and positive associations with meat and saturated fat intake have been reported in several studies; additional studies are needed to confirm or refute these associations. Family history of NHL or other hematolympho-proliferative cancers and personal history of several autoimmune disorders are associated with increased risk of NHL, but are not likely to account for a large proportion of cases. HIV and other infectious agents, such as human herpesvirus 8 and Epstein-Barr, appear to be associated with differing types of NHL, such as some B-cell lymphomas. Future epidemiologic studies should evaluate associations by NHL type, enhance exposure information collected, and elucidate factors that may identify susceptible (or resistant) subpopulations because of genetic, immunologic or other characteristics. The extent to which the etiology of NHL types may differ is important to resolve in ongoing and future studies.

Ependymoma

Ependymomas are rare tumours of neuroectodermal origin classified as myxopapillary ependymoma and subependymoma (grade I), ependymoma (grade II) and anaplastic ependymoma (grade III). The more common location is infratentorial (60%). Age <40 years and extent of surgery appear related to better prognosis, while the role of other prognostic factors, such as tumour grade and tumour site are equivocal. This emphasizes the role of surgery as the standard treatment. Postoperative radiotherapy is indicated in high-grade ependymomas, and is recommended in low-grade ependymomas after subtotal or incomplete resection (confirmed by postoperative MR). Deferral of radiotherapy until recurrence may be considered on an individual basis for patients with MR confirmation of a radical resection. Recommended dose to involved fields is 45-54 Gy for low-grade (grade II) and 54-60 Gy for high-grade ependymomas (grade III). There is no proof that postoperative chemotherapy improves the outcome. At recurrence, platinum-, nitrosourea- or temozolomide-based chemotherapy can be administered, although there is no evidence of efficacy.

Epidemiology and etiology of non-Hodgkin lymphoma--a review

The etiology of non-Hodgkin lymphoma, as well as its global dramatic rise in incidence during the past decades, remains largely unexplained. However, there is increasing awareness that this group of malignancies may entail not only clinical, morphological and molecular heterogeneity, but also considerable variations in terms of etiologic factors. In this review, epidemiologic patterns are summarized as well as current evidence of associations between various known or suspected risk factors for non-Hodgkin lymphoma overall or for any of its subtypes. Central pathogenetic mechanisms include immunosuppression, especially in relation to T-cell function and loss of control of latent EBV infection, and chronic antigen stimulation. Some degree of familiar aggregation also implies a role for genetic susceptibility. A number of recent investigations of non-Hodgkin lymphoma etiology will hopefully lead to a better understanding of the causes of these malignancies.

Mesothelioma mortality in Europe: impact of asbestos consumption and simian virus 40

Background

It is well established that asbestos is the most important cause of mesothelioma. The role of simian virus 40 (SV40) in mesothelioma development, on the other hand, remains controversial. This potential human oncogene has been introduced into various populations through contaminated polio vaccines. The aim of this study was to investigate whether the possible presence of SV40 in various European countries, as indicated either by molecular genetic evidence or previous exposure to SV40-contaminated vaccines, had any effect on pleural cancer rates in the respective countries.

Methods

We conducted a Medline search that covered the period from January 1969 to August 2005 for reports on the detection of SV40 DNA in human tissue samples. In addition, we collected all available information about the types of polio vaccines that had been used in these European countries and their SV40 contamination status.

Results

Our ecological analysis confirms that pleural cancer mortality in males, but not in females, correlates with the extent of asbestos exposure 25 – 30 years earlier. In contrast, neither the presence of SV40 DNA in tumor samples nor a previous vaccination exposure had any detectable influence on the cancer mortality rate in neither in males (asbestos-corrected rates) nor in females.

Conclusion

Using the currently existing data on SV40 prevalence, no association between SV40 prevalence and asbestos-corrected male pleural cancer can be demonstrated.

The epidemiology of non-Hodgkin lymphoma

Non-Hodgkin lymphoma (NHL) includes a group of more than 20 different malignant lymphoproliferative diseases that originate from lymphocytes. Rates of NHL have increased dramatically over the past few decades, although the rate of increase has recently slowed. It is now the sixth most common cancer in Australia. Globally, it is somewhat more common in men than in women, and rates are highest in North America and Australia. The causes of the increase in NHL rates are largely unknown. The best described risk factor for NHL is immune deficiency; rates of NHL are greatly increased, with relative risks of 10-100 or more, in people with immune deficiency associated with immune suppressive therapy after transplantation, HIV/AIDS, and congenital conditions. In addition, some NHL subtypes are associated with specific infections. These include immune-deficiency-associated central nervous system NHL (Epstein-Barr virus); gastric mucosa-associated lymphoid tissue NHL (Helicobacter pylori); adult T-cell leukemia/lymphoma (human T-lymphotrophic virus type 1) and body cavity-based lymphoma (human herpesvirus 8). However, these specific infections account for a very small proportion of total NHL incidence. In addition to immune deficiency and infection, other immune-related conditions are increasingly being recognised as related to NHL risk. Specific autoimmune conditions, including rheumatoid arthritis, systemic lupus erythema, Sjogren's syndrome, psoriasis and coeliac disease are associated with moderately increased risk of NHL. On the other hand, allergic and atopic conditions and their correlates such as early birth order, appear to be associated with a decreased risk of NHL.A variety of other exposures are less strongly related to NHL risk. These include occupational exposures, including some pesticides, herbicides, and solvents. Recently, two studies have reported that sun exposure is associated with a decreased risk of NHL. Smoking appears to be weakly positively associated with risk of follicular NHL, and alcohol intake is associated with a decreased risk of NHL. The pooled analysis of several case-control studies of NHL risk that are currently in the field promises to help clarify which of these risk factors are real, and will contribute to the elucidation of the mechanisms of how disorders of the immune system, and other factors, are related to NHL risk.

No evidence for simian virus 40 DNA sequences in malignant non-Hodgkin lymphomas

DNA sequences coding for simian virus 40 (SV40) large T antigen have been detected at different frequencies in human non-Hodgkin's lymphomas (NHL) by PCR techniques as well as immunohistochemistry. A highly sensitive quantitative real-time PCR specific for a sequence of SV40 large T antigen was established to test whether SV40 DNA is present in malignant lymphomas of German patients. Thirty-three lymph node samples obtained from 27 patients with NHL and 6 patients with Hodgkin's disease (HD) were tested in addition to 48 samples of peripheral blood mononuclear cells (PBMNC) from patients with NHL containing between 0.1% and >90% circulating lymphoma cells determined by PCR. Fourteen lymph nodes obtained from patients with other diseases than malignant lymphomas and 47 PBMNC samples from healthy volunteers served as controls. All samples from patients with malignant lymphomas and all controls were negative for SV40 DNA by quantitative real-time. In contrast, EBV-DNA could be detected in 29 of 46 DNA preparations isolated from lymph nodes (63%) and in 20 of 47 DNA preparations from PBMNC. EBV-positive samples contained between 5 and 80,000 EBV copies per 100,000 cells. Our results do not support the hypothesis that SV40 plays a major role in the etiology of malignant lymphomas and, in addition, they exclude a clonal SV 40 infection of malignant lymphoma cells in all samples investigated.

SV40 and human cancer: A review of recent data

An unknown proportion of formalin-inactivated poliovirus vaccine lots administered to millions of US residents between 1955 and 1963 was contaminated with small amounts of infectious simian virus 40 (SV40), a polyomavirus of the rhesus macaque. It has been reported that mesothelioma, brain tumors, osteosarcoma and non-Hodgkin lymphoma (NHL) contain SV40 DNA sequences and that SV40 infection introduced into humans by the vaccine probably contributed to the development of these cancers. The Immunization Safety Review Committee of the Institute of Medicine (IOM) reviewed this topic in 2002. The present review of recent studies showed that the earlier results describing the recovery of SV40 DNA sequences from a large proportion of the above tumors were not reproducible and that most studies were negative. Contamination with laboratory plasmids was identified as a possible source of false positive results in some previous studies. The low-level immunoreactivity of human sera to SV40 was very likely the result of cross-reactivity with antibodies to the SV40-related human polyomaviruses BKV and JCV, rather than of authentic SV40 infection. SV40 sero-reactivity in patients with the suspect tumors was no greater than that in controls. In epidemiologic studies, the increased incidence of some of the suspect tumors in the 1970s to 1980s was not related to the risk of exposure to SV40-contaminated vaccines. In summary, the most recent evidence does not support the notion that SV40 contributed to the development of human cancers.

Does simian virus 40 cause non-Hodgkin lymphoma? A review of the laboratory and epidemiological evidence

Recently, several studies have reported the detection of DNA from simian virus 40 (SV40), a macaque polyomavirus, in tumor tissues obtained from non-Hodgkin lymphoma (NHL) patients. SV40 accidentally contaminated poliovirus vaccines administered to millions of individuals in 1955-1962. A link between SV40 and NHL is biologically plausible because SV40 causes hematological malignancies in laboratory rodents. However, detection of SV40 DNA in human NHL tumors has not been confirmed by other laboratories. Casting doubt on an association between SV40 and NHL, follow-up studies of recipients of SV40-contaminated poliovirus vaccines have not revealed these individuals to be at increased risk of NHL. Furthermore, 2 recent case-control studies of NHL documented only infrequent SV40 antibody reactivity among NHL cases, and the prevalence of SV40 antibodies was similar in cases and controls. This review summarizes recent laboratory and epidemiological studies bearing on the question of whether SV40 is a cause of NHL in humans. The strengths and weaknesses of these data are discussed, and a framework for considering the collected evidence is presented. Many of the considerations raised in this review apply to the evaluation of data regarding other cancers, such as mesothelioma, brain tumors, and various sarcomas, for which an etiologic link with SV40 also has been proposed.

Is there an association between SV40 contaminated polio vaccine and lymphoproliferative disorders? An age-period-cohort analysis on Norwegian data from 1953 to 1997

Between 1955 and 1963, an estimated number of 150 million people in various parts of the world, including Norway, received poliomyelitis vaccine possibly contaminated with infectious simian virus 40 (SV40). Human studies have investigated the hypothesised association between SV40 and various cancers, but the results have so far been contradicting. The aim of the present study was to examine Norwegian cancer incidence data to assess a possible association between birth cohorts assumed to have been subjected to the vaccine and the incidence rate of lymphoproliferative disorders (excluding Hodgkin's lymphoma), further subdivided into non-Hodgkin's lymphoma (NHL), lymphocytic leukemia and plasma cell neoplasms. Between 1953 and 1997, the incidence rate of lymphoproliferative diseases combined increased about 3-fold in both males and females. Subgroup analysis showed that this increase was largely attributable to NHL. Age-period-cohort modelling of the subgroups, as well as of all groups combined, showed that the cohort effect was more prominent than the period effect. However, the variations in incidence patterns across the birth cohorts did not fit with the trends that would be expected if a SV40 contaminated vaccine did play a causative role. Thus, our data do not support the hypothesis of an association between the vaccine and any subgroup of lymphoproliferative diseases.

Malignant mesothelioma

Malignant mesothelioma is an aggressive, treatment-resistant tumour, which is increasing in frequency throughout the world. Although the main risk factor is asbestos exposure, a virus, simian virus 40 (SV40), could have a role. Mesothelioma has an unusual molecular pathology with loss of tumour suppressor genes being the predominant pattern of lesions, especially the P16INK4A, and P14ARF, and NF2 genes, rather than the more common p53 and Rb tumour suppressor genes. Cytopathology of mesothelioma effusions or fine-needle aspirations are often sufficient to establish a diagnosis, but histopathology is also often required. Patients typically present with breathlessness and chest pain with pleural effusions. Median survival is now 12 months from diagnosis. Palliative chemotherapy is beneficial for mesothelioma patients with high performance status. The role of aggressive surgery remains controversial and growth factor receptor blockade is still unproven. Gene therapy and immunotherapy are used on an experimental basis only. Patterns identified from microarray studies could be useful for diagnosis as well as prognostication.

Markers of Past Infection with Simian Virus 40 (SV40) and Risk of Incident Non-Hodgkin Lymphoma in a Maryland Cohort

Simian virus 40 (SV40) genome sequences have been detected in human non-Hodgkin lymphoma (NHL) tissues, and past infection with SV40 may be a risk factor for NHL. We conducted a population-based nested case-control study to investigate the association between serum antibodies to SV40 and incident NHL. Two research serum banks were established in Washington County, MD, with >45,000 volunteers contributing blood samples collected in 1974 and 1989. Incident cases of NHL diagnosed through 2002 (n = 170) were identified among participants by linkage to population-based cancer registries. Two controls were matched to each case (n = 340) on age, sex, and date of blood draw. Circulating immunoglobulin G antibodies to SV40 were measured using virus-like particle (VLP) ELISA. Positive samples were tested for cross-reactivity with JC virus (JCV) and BK virus (BKV) through competitive inhibition assays. Associations between SV40 antibody seropositivity and NHL were estimated using conditional logistic regression. Whereas SV40 antibodies were detected by VLP ELISA in 15% of cases and 10% of controls [matched odds ratio (OR), 1.97; 95% confidence interval (95% CI), 1.03-3.76], the SV40 reactivity of 85% of the SV40 antibody-positive sera was decreased by adsorption with BKV and/or JCV VLPs. Antibodies specific for SV40 (not cross-reactive) were identified in only 1.8% of cases and 1.6% of controls (OR, 1.51; 95% CI, 0.41-5.52). Our findings suggest that past infection with SV40 is not associated with an increased risk of developing NHL.

History of chickenpox and shingles and prevalence of antibodies to varicella-zoster virus and three other herpesviruses among adults with glioma and controls

Whether viruses or immunologic factors might cause or prevent human brain cancer is of interest. Statistically significant inverse associations of adult glioma with history of chickenpox and immunoglobulin G antibodies to varicella-zoster virus have been reported. The authors evaluate associations of immunoglobulin G antibodies to varicella-zoster virus and three other herpesviruses among 229 adults with glioma and 289 controls in the San Francisco Bay Area Adult Glioma Study (1997-2000). Cases were less likely than controls to report a history of chickenpox (for self-reported cases vs. controls: the age-, gender-, and ethnicity-adjusted odds ratio = 0.59, 95% confidence interval: 0.40, 0.86), and they also had lower levels of immunoglobulin G to varicella-zoster virus (for being in the highest quartile vs. the lowest quartile: the age-, gender-, and ethnicity-adjusted odds ratio = 0.41, 95% confidence interval: 0.24, 0.70). The inverse association with anti-varicella-zoster virus immunoglobulin G was most marked for glioblastoma multiforme cases versus controls and was only somewhat attenuated by excluding subjects taking high-dose steroids and other medications. Cases and controls did not differ notably for positivity to three other herpesviruses, Epstein-Barr virus, cytomegalovirus, and herpes simplex virus. Cohort studies may help to clarify the nature of the association between immunity to and/or clinical manifestations of varicella-zoster virus and glioblastoma.

Absence of simian virus 40 (SV40) DNA in lymphoma samples from Tasmania, Australia

AIMS

It has been postulated that the recent world-wide increase in the incidence of non-Hodgkin's lymphoma (NHL) may have been caused by human infection with simian virus 40 (SV40) (a lymphotropic monkey virus that was introduced to man from contaminated poliovirus vaccines between 1955 and 1963); therefore, we set out to determine the incidence of SV40 DNA positivity in lymphoma samples from patients in Tasmania, Australia.

METHODS

One hundred lymph node samples, 50 from patients with lymphomas and 50 from controls, were tested using PCR amplification of three SV40-specific primer pairs followed by dot-blot hybridisation.

RESULTS

All of the samples tested contained amplifiable DNA, but none contained amplifiable SV40 sequences with any of the primer sets used.

CONCLUSIONS

Our results demonstrate absence of SV40 in the lymphoid tissues of our study population in Tasmania, Australia. SV40 does not explain the increasing incidence of NHL in our population.

Antibody Responses to Simian Virus 40 T Antigen: A Case-Control Study of Non-Hodgkin Lymphoma

A possible role for SV40, a macaque polyomavirus, in non-Hodgkin lymphoma (NHL) in humans was raised recently by the reported detection of SV40 DNA in tumor tissue. Animals with SV40-induced tumors frequently produce high-level antibodies against T antigen, the SV40 oncoprotein. In this study, we assessed whether SV40 T antibody measured in humans supported a relationship between SV40 and NHL. Subjects were sampled from a U.S. population-based case-control study of NHL, according to presence of antibodies against capsids of SV40 and BK, a related human polyomavirus (n = 85 cases, n = 95 controls). T antibody was measured by enzyme immunoassay. We also evaluated serum specimens from SV40-infected and SV40-uninfected macaques (n = 19 and n = 8, respectively), SV40-uninfected hamsters (n = 5), and hamsters with SV40-induced tumors (n = 10). Hamsters with SV40-induced tumors all produced robust SV40 T antibody [median absorbance, 0.99), whereas SV40-uninfected hamsters and macaques had much lower levels (median absorbance, 0.05 and 0.04, respectively). NHL cases, controls, and SV40-infected macaques resembled these latter two groups, generally showing only low-level T antibody (median absorbance, 0.03, 0.04, and 0.04, respectively). Overall, only five cases (6%) and five controls (5%) had T antibody responses classified as seropositive (odds ratio, 1.2; 95% confidence interval, 0.3-4.6). Interestingly, all 10 humans with T antibody responses also showed antibody responses to BK capsid. We found no association between the presence of T antibody and NHL, arguing against SV40 as a cause of NHL. Infrequent and low-level T antibody responses among humans could represent cross-reactivity to BK virus T antigen.

Update on side effects from common vaccines

Vaccines have had a tremendous impact on public health by reducing morbidity and mortality from a variety of virulent pathogens. However, unintended side effects continue to pose a potential risk that may outweigh the vaccine's protective attributes. In this review, we discuss recent articles and controversies pertaining to vaccine-associated adverse events. Included in the discussion are influenza, hepatitis B, measles-mumps-rubella, diphtheria-tetanus-pertussis, polio, Haemophilus influenzae type b, and rotavirus vaccines. The importance and contribution of vaccine constituents (such as thimerosal) to side effects is also reviewed.

Causality of mesothelioma: SV40 question

The fragility of the evidence for SV40 association with human cancer is seen in studies of NHL. A publication in 1999 stated that SV40 is rarely present in NHL. In 2002, two laboratories reported SV40 sequences in 42% to 43% of cases of NHL . One of these laboratories also detected SV40 sequences in small proportions of pediatric tumors (e.g., Wilm's tumor, hepatoblastoma, rhabdomyosarcoma, medulloblastoma, osteosarcoma, and retinoblastoma) and adult carcinomas (e.g., lung, colon, breast, and prostate) These positive results were not confirmed in subsequent studies published in 2003. Capello et al and Mackenzie et al failed to detect SV40 sequences in NHL tissues. Sanjose et al examined sera from patients with NHL and from controls for antibodies reactive to SV40 VLPs, and they detected no significant differences between the two groups. The association of SV40 with NHL is in doubt. An etiologic link between a virus and a cancer becomes plausible when evidence from different lines of enquiry (e.g., epidemiology, pathogenesis, and molecular mechanisms) is mutually reinforcing and together provides a coherent picture that can connect the biology the virus to the characteristics of the disease. The associations of human papillomaviruses with cervical cancer and hepatitis B and C viruses with hepatocellular carcinoma are examples in which the etiologic link is clear. With SV40 and mesothelioma, the data on viral sequences in tumors is inconsistent and disputed, and serologic evidence does not support any association. The epidemiologic data do not show that documented exposures tt SV40 increase the risk of mesothelioma. It seems improbable that a single virus (which cannot be conclusively demonstrated to be present in the community) contributes to the development of such a wide variety of tumors, spanning all age groups and histologic types. The weaknesses in the evidence linking SV40 with mesothelioma are summarized in Box 11 It seems unlikely that infection with SV40 contributes to the development of human mesothelioma or any other human cancer.

Evidence against a role for SV40 infection in human mesotheliomas and high risk of false-positive PCR results owing to presence of SV40 sequences in common laboratory plasmids

BACKGROUND

PCR-based evidence of infection by simian virus 40 (SV40) has been reported in varying proportions of pleural mesotheliomas and other tumours, but data are conflicting and reproducibility limited. During a study of SV40 in relation to homozygous deletion of CDKN2A in mesotheliomas, we became concerned by inconsistent results and therefore used several independent techniques to investigate SV40 in these tumours.

METHODS

High-quality DNA and RNA were extracted from 71 frozen mesothelioma samples. DNA PCR was done with four sets of primers for the SV40 T-antigen gene. RNA transcripts were examined by RT-PCR.

FINDINGS

The first two primer sets for DNA PCR gave positive results in proportions similar to those reported in positive studies (56-62%) but there were unusual reproducibility difficulties. These primers were in a region of the T-antigen gene (nucleotides 4100-4713) that is present in many common laboratory plasmids. In assays with PCR primers not included within that region, only four cases (6%) showed products but these were too faint to suggest clonal infection. Further PCR assays confirmed that the SV40 sequences in the tumour samples had a deletion found only in plasmids, not in native functional SV40. Review of previous studies showed a similar pattern of discrepancies between SV40 T-antigen DNA PCR results obtained with primers within and beyond the region 4100-4713. All 71 mesotheliomas were negative for T-antigen transcripts by RT-PCR, and lacked T-antigen-positive tumour cells by immunohistochemistry.

INTERPRETATION

Our data based on three independent experimental approaches do not support a significant role for SV40 in human mesotheliomas. The risk of false-positive results due to contamination by common laboratory plasmids containing SV40 sequences has been underestimated. Studies of SV40 based on PCR methods require careful primer design to reduce this risk.

RELEVANCE TO PRACTICE

This paper presents several lines of evidence against the proposed link between SV40 infection and human mesotheliomas. Studies reporting a high prevalence of SV40 DNA in human tumours have been based on molecular assays prone to false-positive results. Because SV40 appears unlikely to have a major role, if any, in human mesotheliomas, clinicians should continue to consider asbestos exposure as the most likely and most thoroughly established aetiological factor in individuals with this cancer.

Epidemiology and genetics of childhood cancer

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

Case-Control Study of Simian Virus 40 and Non-Hodgkin Lymphoma in the United States

BACKGROUND

Recent studies have reported detection of simian virus 40 (SV40) DNA in tumor tissues from 15%-43% of U.S. non-Hodgkin lymphoma (NHL) patients. SV40 accidentally contaminated U.S. poliovirus vaccines that were widely administered from 1955 through 1962. However, epidemiologic data linking SV40 with NHL are lacking.

METHODS

We obtained serum samples from 724 incident NHL case patients and 622 control subjects from a population-based U.S. case-control study. SV40 serostatus was analyzed by two independent laboratories (designated A and B) using similar virus-like particle (VLP) enzyme immunoassays. Associations with serostatus were assessed with logistic regression, adjusting for sex, race, birth year, and study site. VLPs for the human polyomaviruses BK and JC were used in competitive inhibition experiments to assess the specificity of SV40 reactivity. Statistical tests were two-sided.

RESULTS

SV40 antibody results from the two laboratories were correlated (R = 0.59; P<.001). Laboratories A and B detected SV40 seropositivity in 7.2% and 9.8% of NHL case patients, respectively, and in 10.5% and 9.6% of control subjects, respectively. SV40 seropositivity was not associated with increased NHL risk (laboratory A: adjusted odds ratio [OR] = 0.68, 95% confidence interval [CI] = 0.46 to 1.00; laboratory B: adjusted OR = 1.02, 95% CI = 0.71 to 1.47). SV40 seropositivity was not associated with NHLs of any specific histology or site. Among subjects born before 1963, 1.0%-1.6% showed SV40-specific reactivity, i.e., SV40 reactivity confirmed in competitive inhibition experiments, whereas (based on limited data) none born subsequently demonstrated SV40-specific reactivity.

CONCLUSIONS

In persons born before 1963, the presence of SV40-specific antibodies, although rare, could reflect exposure to SV40-contaminated vaccines. Nevertheless, NHL risk was unrelated to serologic evidence of SV40 exposure or infection.

Polio vaccines, Simian Virus 40, and human cancer: the epidemiologic evidence for a causal association

In 1960, it was discovered that Simian Virus 40 (SV40) contaminated up to 30% of the poliovirus vaccines in the US. This contamination arose because the vaccines were produced in monkey kidney cell cultures harboring SV40 between 1955 and 1963. During this period, approximately 90% of children and 60% of adults in the USA were inoculated for polio and possibly exposed to SV40. Many epidemiologic and molecular pathogenesis studies have been conducted in order to identify potential cancer risks since this 'natural' experiment began. Productive SV40 infection has the potential to initiate malignancy in a variety of target tissues. Epidemiological studies that investigated the relationship between SV40 infection and cancer risks have yielded mixed results. Studies can be grouped into three categories based on their exposure definition of SV40 infection: (1) use of vaccination or birth cohorts as proxy variables for infection, (2) follow-up of children of pregnant women who received polio vaccines, and (3) direct molecular detection of the virus or serologic detection of anti-SV40 antibody responses. A meta-analysis of five published studies did not support the hypothesis that SV40 exposure increases the overall risk of cancer incidence or cancer mortality. The analysis of specific cancer sites is largely inconclusive because of substantial problems that most studies have had in reliably defining exposure, defining latency effects, or dealing with confounding and other biases. A new generation of molecular epidemiologic studies is necessary to properly address these issues.

Ependymal tumors

Ependymal tumors are rare malignancies that arise from the cells that line the ventricles and central canal of the spinal cord. Although they are more common in children, adults may also be effected by ependymal tumors. Prognosis is dependent on tumor location, histology, especially for myxopapillary tumors that tend to occur in the lumbar spine, extent of surgical resection, and stage of disease. Standard therapy consists of complete resection when feasible. The exact role of adjuvant radiotherapy in patients with radiographically confirmed complete resection is poorly defined. Patients with known residual disease may benefit from local radiation therapy, but the extent of radiation field and total dose are controversial. Even in patients treated with involved field radiotherapy, most relapses occur within the original tumor bed, thus local control remains the biggest obstacle to effective therapy. Chemotherapy has little impact against this tumor and has no role in the adjuvant setting, outside of a well designed clinical trial, with the possible exception of children younger than 5 years in an effort to delay radiation. A minority of patients may respond to one of several chemotherapy regimens at the time of recurrence, but the impact of this therapy is limited. Newer treatment strategies are needed.

An update of the epidemiology of non-Hodgkin's lymphoma

The incidence of non-Hodgkin's lymphoma (NHL) has increased approximately 80% since the 1970s, and is now the fifth most common cancer in the United States. The incidence of NHL is approximately 50% higher among men than women and 35% higher among white people than black people. The incidence rates of all subtypes of NHL have increased, especially diffuse large-cell and immunoblastic subtypes. Extranodal NHL has increased more rapidly than nodal NHL. The overall NHL incidence rates stabilized in the early 1990s and then began to decrease between 1996 and 2000, resulting in part from a decrease in the incidence of AIDS. The incidence of NHL types not associated with AIDS and NHL in groups at low risk of AIDS has continued to increase throughout the 1990s. The increasing incidence of NHL is poorly understood. Improved diagnostic techniques, the effects of the human immunodeficiency virus epidemic, and immunosuppressive therapies accounted for only one third of the increase. Increase in NHL may be attributed to immunodeficiency, various infections, familial aggregation, blood transfusion, genetic susceptibility to NHL, diet, and chemical exposures to pesticides and solvents. Some studies also suggest that associations between risk factors and specific NHL subtypes may be stronger than associations between the same risk factors and NHL in aggregate. Future epidemiologic studies should incorporate the new World Health Organization classification of NHL and new techniques such as cytogenetic molecular analyses to identify subtype-specific etiologic factors. Evaluation of polymorphisms in genes involved in immune function, inflammation, and the activation or detoxification of environmental and occupational chemicals is also warranted.

Simian virus 40 and its association with human lymphomas

Simian virus 40 (SV40) is a potent DNA tumor virus that is known to induce cancer in laboratory animals. The neoplasias induced by SV40 in animal models are brain cancers, mesothelioma, bone cancers, and systemic lymphomas. SV40 oncogenesis is mediated primarily by the viral large tumor antigen, which inactivates the tumor suppressor proteins p53 and pRb family members. Evidence indicates that SV40 is an emergent human pathogen and that a significant excess risk of SV40 is associated with primary human brain cancers, malignant mesothelioma, bone cancers, and non-Hodgkin's lymphoma. Therefore, the major types of tumors induced by SV40 in laboratory animals are the same as those human malignancies found to contain SV40 markers. Experimental and clinical data indicate that SV40 may be functionally important in the development of some of those malignancies. Recently, the Institute of Medicine of the National Academies concluded that SV40 infections could lead to cancer in humans under natural conditions (based on moderate strength biologic evidence). This review examines the data implicating SV40 in the pathogenesis of human lymphomas and discusses future directions to define the causative role for SV40 in these malignancies.