Cancer Risk Studies and Priority Areas for Cancer Risk Appraisal in Uganda.

Background: Research into aetiologies and prevention of the commonest cancers and implementation of primary and secondary prevention can reduce cancer risk and improve quality of life. Moreover, monitoring the prevalence of cancer risk factors in a specific population helps guide cancer prevention and early detection efforts and national cancer control programming. Objective: This article aims to provide the scope and findings of cancer risk studies conducted in Uganda to guide researchers, health-care professionals, and policymakers. Methods: Between November 2019 to January 2020, we searched peer-reviewed published articles in Pubmed, EMBASE and Cochrane Library (Cochrane central register of controlled trials-CENTRAL). We followed the recommendation of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses - the PRISMA. The primary focus was to identify cancer risk and prevention studies conducted in Uganda and published in peer-reviewed journals from January 2000 and January 2020. We used key Boolean search terms with their associated database strings. Results: We identified 416 articles, screened 269 non-duplicate articles and obtained 77 full-text articles for review. Out of the 77 studies, we identified one (1%) randomized trial, two (2.5%) retrospective cohort studies and 14 (18%) case-control studies, 46 (60%) cross-sectional studies, five (6.4%) ecological studies, three panel studies (4%) and six (8%) qualitative studies. Cervical cancer was the most studied type of cancer in Uganda (23.4%, n = 18 studies), followed by lymphomas - both Hodgkin and Non-Hodgkin sub-types (20.7%), n = 16 studies) and breast cancer (15.6%, n = 12 studies). In lymphoma studies, Burkitt lymphoma was the most studied type of lymphoma (76%, n = 13 studies). The studies concentrated on specific cancer risk awareness, risk perceptions, attitudes, uptake of screening, uptake of human papillomavirus vaccination, the prevalence of some of the known cancer risk factors and obstacles to accessing screening services. Conclusion: The unmet need for comprehensive cancer risk and prevention studies is enormous in Uganda. Future studies need to comprehensively investigate the known and putative cancer risk factors and prioritize the application of the higher-hierarchy evidence-generating epidemiological studies to guide planning of the national cancer control program.

The promise of a prophylactic Epstein-Barr virus vaccine.

The worldwide burden of disease due to Epstein-Barr virus (EBV) infection is enormous. Diseases include endemic Burkitt lymphoma, infectious mononucleosis, cancers after transplantation, Hodgkin lymphoma, and nasopharyngeal carcinoma. A prophylactic EBV vaccine has the potential to significantly reduce the incidence and/or the severity of all these diseases. Infectious mononucleosis can be nasty and prolonged with a median duration of 17 days. Patients, especially children, undergoing bone marrow or solid organ transplantation may develop post-transplant lymphoproliferative disorder (PTLD). Preventing or modifying primary EBV infection could reduce the incidence PTLD, and also certain lymphomas and nasopharyngeal carcinoma. EBV is a major environmental risk factor for multiple sclerosis (MS). Contracting EBV is essential to getting MS, and having a childhood case of infectious mononucleosis increases that risk. Vaccinating against EBV could be vaccinating against MS.

Construction of Epstein-Bar virus cocktail peptide fused with Fcγ of IgG: as a potential delivery system for vaccine development.

Epstein-Barr virus (EBV) associated with several diseases such as contagious mononucleosis chronic active EBV infection, and diverse sorts of malignant tumors. Therefore, using applicable vaccines could be advantageous for public health. Yet, the vaccine has been unavailable to protect from EBV so far. In the current study, to develop a multi-peptide vaccine for EBV and assess its expression in Pichia pastoris yeast system, three immunodominant sequences in glycoprotein (gp) 85, gp350 and latent membrane protein 1 (LMP1) were chosen. To construct fusion peptide, -GGGGS- liker was applied. After cloning the fusion peptide in the pPICZαA expression vector, this recombinant vector processed and transfected into Pichia pastoris host cells. The expression of high level of EBV fusion peptide was confirmed by dot blot and SDS-PAGE procedures. The Pichia pastoris is capable of supporting EBV fusion peptide expression. The application of this fusion peptide as a peptide vaccine to fight EBV is suggested.

Synergistic Protective Effect of Sickle Cell Trait and Blood Group-O on the Risk of Endemic Burkitt's Lymphoma.

BACKGROUND: Previous research strongly suggest that malaria is an important factor in the pathogenesis of endemic Burkitt's lymphoma (eBL). Therefore, genetic factors such as sickle cell trait (SCT) and blood group-O that offer protection against severe malaria would be expected to reduce the risks of eBL. However, previous reports on the protective roles of SCT and blood group-O against the risks of eBL were inconclusive. Hence, the need for further studies on the protective roles of SCT and blood group-O separately, and also to investigate whether or not the combined anti-severe malaria protective roles of SCT and blood group-O have synergistic effects in reducing the risks of eBL. We therefore hypothesize that SCT and blood group-O are independently associated with reduced risks of eBL, and the co-inheritance of both factors (SCT and group-O) would provide greater protection against eBL. If our hypothesis is correct, children who inherited both SCT and blood group-O would have lower risks of eBL than their counterparts who inherited SCT or blood group-O separately. To the best of our knowledge, the possible synergistic relationship between SCT and blood group-O with regards to the risk of eBL has not been previously studied. PATIENTS AND METHODS: We conducted a retrospective logistic regression analysis of the frequencies of Hb phenotypes and ABO blood groups among patients with eBL in order to determine the separate and synergistic protective effects of SCT and blood group-O on the risk of eBL in Nigeria where eBL is among the most common malignant childhood cancers. RESULTS: The Odd Ratios (OR) for the risk of eBL were 0.52 for 'SCT irrespective of ABO blood group'; 0.49 for 'blood group-O irrespective of Hb phenotype'; and 0.23 for 'SCT with blood group-O'. DISCUSSION: These values suggest that both SCT and blood group-O are independently associated with modest reduction in the risk of eBL. However, when SCT with blood group-O was assessed for the risk factor for eBL, we obtained an Odds ratio of 0.23, which was significantly lower than the OR values for SCT (0.52) and blood group-O (0.49) separately. These figures suggest that coinheritance of SCT and blood group-O offers greater reduction in the risk of eBL than that provided by either SCT or blood group-O separately. The greater protection against eBL provided by the coinheritance of SCT and blood group-O is interpreted to be the resultant synergistic effect of the combined anti-malarial attributes of SCT and blood group-O. CONCLUSION: These findings suggest that the combined anti-malarial protective roles of SCT and blood group-O have synergistic effects in reducing the risks of eBL. This study has provided further evidence on the association between malaria-protective genetic polymorphisms and eBL, which is consistent with the aetiologic role of malaria in the pathogenesis of the tumour. Hence, the need for malaria endemic countries to intensify malaria control programs in order to curtail the incidence of eBL.

Analysis of the role of intratecal liposomal cytarabine in the prophylaxis and treatment of central nervous system lymphomatosis: The Balearic Lymphoma Group experience.

Central nervous system (CNS) lymphomatosis is a fatal complication of aggressive non-Hodgkin lymphoma (NHL). In lymphoblastic or Burkitt lymphoma, without specific CNS prophylaxis the risk of CNS relapse is 20-30%. DLBCL has a lower risk of relapse (around 5%) but several factors increase its incidence. There is no consensus or trials to conclude which is the best CNS prophylaxis. Best results seem to be associated with the use of intravenous (iv) high-dose methotrexate (HDMTX) but with a significant toxicity. Other options are the administration of intrathecal (IT) MTX, cytarabine or liposomal cytarabine (ITLC). Our aim is to analyze the experience of the centers of the Balearic Lymphoma Group (BLG) about the toxicity and efficacy of ITLC in the prophylaxis and therapy of CNS lymphomatosis. We retrospectively reviewed cases from 2005 to 2015 (n = 58) treated with ITLC. Our toxicity results were: 33% headache, 20% neurological deficits, 11% nausea, 9% dizziness, 4% vomiting, 4% fever, 2% transient blindness and 2% photophobia. In the prophylactic cohort (n = 26) with a median follow-up of 55 months (17-81) only 3 CNS relapses (11%) were observed (testicular DLBCL, Burkitt and plasmablastic lymphoma, with a cumulative incidence of 8%, 14% and 20% respectively). In the treatment cohort (n = 32), CSF complete clearance was obtained in 77% cases. Median OS was 6 months (0-16). Death causes were lymphoma progression (19 patients, 79%), treatment toxicity (2 patients) and non-related (3 patients, 12%). Toxicity profile was good especially when concomitant dexamethasone was administered. In the prophylactic cohort the incidence of CNS relapse in DLBCL group was similar to previously reported for HDMTX and much better than IT MTX. A high number of ITLC injections was associated with better rates of CSF clearance, clinical responses, PFS and lower relapses. Survival is still poor in CNS lymphomatosis and new therapeutic approaches are still needed.

Carnitine-acyltransferase system inhibition, cancer cell death, and prevention of myc-induced lymphomagenesis.

BACKGROUND: The metabolic alterations of cancer cells represent an opportunity for developing selective antineoplastic treatments. We investigated the therapeutic potential of ST1326, an inhibitor of carnitine-palmitoyl transferase 1A (CPT1A), the rate-limiting enzyme for fatty acid (FA) import into mitochondria. METHODS: ST1326 was tested on in vitro and in vivo models of Burkitt's lymphoma, in which c-myc, which drives cellular demand for FA metabolism, is highly overexpressed. We performed assays to evaluate the effect of ST1326 on proliferation, FA oxidation, and FA mitochondrial channeling in Raji cells. The therapeutic efficacy of ST1326 was tested by treating Eµ-myc mice (control: n = 29; treatment: n = 24 per group), an established model of c-myc-mediated lymphomagenesis. Experiments were performed on spleen-derived c-myc-overexpressing B cells to clarify the role of c-myc in conferring sensitivity to ST1326. Survival was evaluated with Kaplan-Meier analyses. All statistical tests were two-sided. RESULTS: ST1326 blocked both long- and short-chain FA oxidation and showed a strong cytotoxic effect on Burkitt's lymphoma cells (on Raji cells at 72 hours: half maximal inhibitory concentration = 8.6 µM). ST1326 treatment induced massive cytoplasmic lipid accumulation, impairment of proper mitochondrial FA channeling, and reduced availability of cytosolic acetyl coenzyme A, a fundamental substrate for de novo lipogenesis. Moreover, treatment with ST1326 in Eµ-myc transgenic mice prevented tumor formation (P = .01), by selectively impairing the growth of spleen-derived primary B cells overexpressing c-myc (wild-type cells + ST1326 vs. Eµ-myc cells + ST1326: 99.75% vs. 57.5%, difference = 42.25, 95% confidence interval of difference = 14% to 70%; P = .01). CONCLUSIONS: Our data indicate that it is possible to tackle c-myc-driven tumorigenesis by altering lipid metabolism and exploiting the neoplastic cell addiction to FA oxidation.

Novel function of scutellarin in inhibiting cell proliferation and inducing cell apoptosis of human Burkitt lymphoma Namalwa cells.

Anti-lymphoma therapy continues to present a major challenge. Even though cytotoxic therapy, immunotherapy and molecularly targeted therapy have been used in the clinic to treat the disease, effective anti-lymphoma drugs are still needed. In this study, we explored novel anti-lymphoma agents and found that scutellarin, an active component of a traditional Chinese medicinal herb Erigeron breviscapus, executed an anti-lymphoma effect. Scutellarin diminished the proliferation of B-lymphoma Namalwa cells in vitro and inhibited lymphoma growth in Namalwa cell-xenotransplanted mice without obvious toxicity. A mechanism study showed that scutellarin at doses of less than 10 µM induced cell cycle arrest at G0/G1 transition without the induction of cell apoptosis, which was accompanied by down-regulation of cyclin D1 and CDK4 expression. In contrast, scutellarin at concentrations of 15 µM or above promoted Namalwa cell apoptosis, which was partially associated with the activation of caspases. These results suggest that scutellarin is a new potential anti-lymphoma candidate.

Combining mTor inhibitors with rapamycin-resistant T cells: a two-pronged approach to tumor elimination.

Despite activity as single agent cancer therapies, Rapamycin (rapa) and its rapalogs may have their greatest effects when combined with other therapeutic modalities. In addition to direct antitumor activity, rapalogs reverse multiple tumor-intrinsic immune evasion mechanisms. These should facilitate tumor-specific T cell activity, but since rapa directly inhibits effector T cells, this potential immune enhancement is lost. We hypothesized that if T cells were rendered resistant to rapa they could capitalize on its downregulation of tumor immune evasion. We therefore modified T cells with a rapa-resistant mutant of mTor, mTorRR, and directed them to B lymphomas by coexpressing a chimeric antigen receptor (CAR) for CD19 (CAR.CD19-28ζ). T cells expressing transgenic mTorRR from a piggyBac transposon maintain mTor signaling, proliferate in the presence of rapa and retain their cytotoxic function and ability to secrete interferon-γ (IFNγ) after stimulation, effector functions that were inhibited by rapa in control T cells. In combination, rapa and rapa-resistant-CAR.CD19-28ζ-expressing T cells produced greater antitumor activity against Burkitt's lymphoma and pre-B ALL cell lines in vitro than CAR.CD19-28ζ T cells or rapa alone. In conclusion, the combination of rapa and rapa-resistant, CAR.CD19-28ζ-expressing T cells may provide a novel therapy for the treatment of B cell malignancies and other cancers.

A recombinant immunotoxin targeting CD22 with low immunogenicity, low nonspecific toxicity, and high antitumor activity in mice.

Recombinant immunotoxins (RITs) are genetically engineered proteins designed to kill cancer cells. The RIT HA22 contains the Fv portion of an anti-CD22 antibody fused to a 38 kDa fragment of Pseudomonas exotoxin A (PE38). As PE38 is a bacterial protein, patients frequently produce antibodies that neutralize its activity, preventing retreatment. We have earlier shown in mice that PE38 contains 7 major B-cell epitopes located in domains II and III of the protein. Here we present a new mutant RIT, HA22-LR-6X, in which we removed most B-cell epitopes by deleting domain II and mutating 6 residues in domain III. HA22-LR-6X is cytotoxic to several lymphoma cell lines, has very low nonspecific toxicity, and retains potent antitumor activity in mice with CA46 lymphomas. To assess its immunogenicity, we immunized 3 MHC-divergent strains of mice with 5 microg doses of HA22-LR-6X, and found that HA22-LR-6X elicited significantly lower antibody responses than HA22 or other mutant RITs with fewer epitopes removed. Furthermore, large (50 microg) doses of HA22-LR-6X induced markedly lower antibody responses than 5 microg of HA22, indicating that high doses can be administered with low immunogenicity. Our experiments show that we have correctly identified and removed B-cell epitopes from PE38, producing a highly active immunotoxin with low immunogenicity and low animal toxicity. Future studies will determine if these properties carry over to humans with cancer.

IL-21-mediated potentiation of antitumor cytolytic and proinflammatory responses of human V gamma 9V delta 2 T cells for adoptive immunotherapy.

Vgamma9Vdelta2 T lymphocytes are a major human gammadelta T cell subset that react against a wide array of tumor cells, through recognition of phosphorylated isoprenoid pathway metabolites called phosphoantigens. Immunotherapeutic protocols targeting Vgamma9Vdelta2 T cells have yielded promising, yet limited, signs of antitumor efficacy. To improve these approaches, we analyzed the effects on gammadelta T cells of IL-21, a cytokine known to enhance proliferation and effector functions of CD8(+) T cells and NK cells. IL-21 induced limited division of phosphoantigen-stimulated Vgamma9Vdelta2 T cells, but did not modulate their sustained expansion induced by exogenous IL-2. Vgamma9Vdelta2 T cells expanded in the presence of IL-21 and IL-2 showed enhanced antitumor cytolytic responses, associated with increased expression of CD56 and several lytic molecules, and increased tumor-induced degranulation capacity. IL-21 plus IL-2-expanded Vgamma9Vdelta2 T cells expressed higher levels of inhibitory receptors (e.g., ILT2 and NKG2A) and lower levels of the costimulatory molecule NKG2D. Importantly, these changes were rapidly and reversibly induced after short-term culture with IL-21. Finally, IL-21 irreversibly enhanced the proinflammatory Th1 polarization of expanded Vgamma9Vdelta2 T cells when added at the beginning of the culture. These data suggest a new role played by IL-21 in the cytotoxic and Th1 programming of precommitted Ag-stimulated gammadelta T cells. On a more applied standpoint, IL-21 could be combined to IL-2 to enhance gammadelta T cell-mediated antitumor responses, and thus represents a promising way to optimize immunotherapies targeting this cell subset.

Antimalarial therapy prevents Myc-induced lymphoma.

The two modes of self-destruction at the cellular level - apoptosis (self-killing) and autophagy (self-eating) - are thought to be tumor suppressive. In particular, germline loss of function of genes involved in autophagy has been associated with tumorigenesis. However, recent studies, including the one by Maclean et al. reported in this issue of the JCI, indicate that autophagy can provide a means for cell survival when nutrients are limiting, such that inhibition of autophagy by the antimalarial drug chloroquine can inhibit tumorigenesis, specifically Myc-induced lymphoma in mice (see the related article beginning on page 79). These findings suggest that a new use of an old drug for cancer prevention may profoundly affect disease outcome.

Targeting lysosomal degradation induces p53-dependent cell death and prevents cancer in mouse models of lymphomagenesis.

Despite great interest in cancer chemoprevention, effective agents are few. Here we show that chloroquine, a drug that activates the stress-responsive Atm-p53 tumor-suppressor pathway, preferentially enhances the death of Myc oncogene-overexpressing primary mouse B cells and mouse embryonic fibroblasts (MEFs) and impairs Myc-induced lymphomagenesis in a transgenic mouse model of human Burkitt lymphoma. Chloroquine-induced cell death in primary MEFs and human colorectal cancer cells was dependent upon p53, but not upon the p53 modulators Atm or Arf. Accordingly, chloroquine impaired spontaneous lymphoma development in Atm-deficient mice, a mouse model of ataxia telangiectasia, but not in p53-deficient mice. Chloroquine treatment enhanced markers of both macroautophagy and apoptosis in MEFs but ultimately impaired lysosomal protein degradation. Interestingly, chloroquine-induced cell death was not dependent on caspase-mediated apoptosis, as neither overexpression of the antiapoptotic protein Bcl-2 nor deletion of the proapoptotic Bax and Bak affected chloroquine-induced MEF death. However, when both apoptotic and autophagic pathways were blocked simultaneously, chloroquine-induced killing of Myc-overexpressing cells was blunted. Thus chloroquine induces lysosomal stress and provokes a p53-dependent cell death that does not require caspase-mediated apoptosis. These findings specifically demonstrate that intermittent chloroquine use effectively prevents cancer in mouse models of 2 genetically distinct human cancer syndromes, Burkitt lymphoma and ataxia telangiectasia, suggesting that agents targeting lysosome-mediated degradation may be effective in cancer prevention.

Synthesis and inhibitory activity of new benzimidazole derivatives against Burkitt's lymphoma promotion.

As a continuation to our previous work concerning antitumor benzimidazoles, we have synthesized series of new derivatives of 2-(1-benzyl-2-methyl-1H-benzimidazol-5-ylimino)-3-(substituted)-thiazolidin-4-one (6a-e), 3-(2-methyl-1H-benzimidazol-5-yl)-2-substituted-thiazolidin-4-one (9a-f) and we have studied their inhibitory activity against the Epstein-Barr virus-early antigen (EBV-EA) activation introduced by 12-O-tetradecanoylphorbol-13-acetate (TPA). Compound 6d was found to be significantly active and compounds 5a and 6e were also active.

Thioredoxin overexpression in mice, model of attenuation of oxidative stress, prevents benzene-induced hemato-lymphoid toxicity and thymic lymphoma.

OBJECTIVE: Reactive oxygen species (ROS), generated following benzene exposure, are considered to trigger the development of hematopoietic neoplasms, although little supporting evidence has been found. In this study, we examined whether the experimental elimination of ROS generated following benzene exposure prevents the development of benzene-induced hematopoietic disorders to clarify the mechanism underlying the development of benzene-induced hematopoietic disorders. METHODS: C57BL/6 mice, overexpressing human thioredoxin (h-Trx-Tg), were used to examine the possible nullification of ROS induction following benzene exposure. The experimental group was exposed to 300 ppm benzene 6 hours/day, 5 days/week, for 26 weeks, and lifetime observation followed by molecular and histopathological examinations were carried out. RESULTS: The present study using h-Trx-Tg mice showed a complete suppression of the development of thymic lymphoma induced by benzene inhalation (0% in h-Trx-Tg vs 30% in wild-type (Wt) mice). This was associated with a 48% decrease in the incidence of clastogenic micronucleated reticulocyte induction in the h-Trx-Tg mice compared with the Wt control after 2 weeks of inhalation. As underlying mechanisms, the attenuation of oxidative stress was accompanied by a complete abrogation of hemato-lymphoid toxicity, as shown by the upregulation of the activity of superoxide-dismutase, and a consequently stable ROS level, as determined by cell sorting using 2', 7'-dichlorodihydrofluorescein diacetate, along with a significant attenuation of the overexpression of a cell cycle-dependent kinase inhibitor, p21. CONCLUSION: The attenuation of benzene-induced oxidative stress and that of the consequent lymphomagenesis were observed for the first time, and these indicate a role of oxidative stress in benzene-induced clastogenesis and lymphomagenesis. (These attenuations were not seen in nonthymic lymphomas, and no leukemias developed in C57BL/6 used in this study.) During the constitutive overexpression of h-Trx, the expression of aryl-hydrocarbon receptor in h-Trx-Tg mice was downregulated, which may also contribute to the attenuation.

A mouse monoclonal antibody against Epstein-Barr virus envelope glycoprotein 350 prevents infection both in vitro and in vivo.

A mouse monoclonal antibody (MAb) against Epstein-Barr virus (EBV) envelope glycoprotein 350, 72A1, inhibited EBV infection of B lymphocytes in vitro. When severe combined immunodeficient mice were injected with EBV-seronegative donors' peripheral-blood mononuclear cells and challenged with EBV, 72A1 MAb prevented development of EBV-positive tumors: none of the test mice (0/12) developed EBV-positive tumors. In contrast, 67% (8/12) of control mice developed EBV-positive tumors (P=.001). Purified 72A1 MAb was infused into 1 healthy adult and 4 EBV-seronegative children after liver transplant. No adverse reactions were seen in the adult or in 3 of the transplant recipients. The remaining patient developed a hypersensitivity reaction, thus underlining the need to humanize the MAb.

Central nervous system-directed preventative therapy in adults with lymphoma.

All adult patients with Burkitt lymphoma or lymphoblastic lymphoma should receive central nervous system (CNS)-directed therapy with both intrathecal and high-dose systemic chemotherapy. There is no evidence to support the routine use of prophylactic CNS-directed therapy in any specific subgroup of adult patients with 'low grade' lymphomas. There are some anatomical sites where involvement by lymphoma is associated with a higher risk of CNS relapse. These probably include testis, breast, paranasal sinuses and the epidural space. Multivariate analyses strongly support a raised serum lactate dehydrogenase level and the involvement of more than one extranodal site as the strongest predictors of subsequent CNS relapse. A high International Prognostic Index score may replace the use of the above two factors in combination. There is evidence of good efficacy when intrathecal chemotherapy and high-dose systemic chemotherapy are used in combination. It is not clear how the best balance between the 'sensitivity' and 'specificity' of the choice of patients to receive CNS-directed therapy can be achieved.

Infecção pelo vírus epstein-barr e oncogênese: [revisão] / Epstein-Barr virus infection and oncogenesis: [review]

As infecções como um todo associam-se a 15% a 20% dos cânceres em geral. Entre os agentes etiológicos carcinogênicos, destacam-se os vírus oncogênicos. O vírus Epstein-Barr (VER) é o mais potente vírus indutor de transformação e crescimento celular conhecido, sendo capaz de imortalizar linfócitos B humanos. Está relacionado com o linfoma de Burkitt, o carcinoma nasofaríngeo e outros tipos de neoplasia. Porém, não se sabe ao certo se o VER seria apenas um componente inocente ou se contribui realmente para o desenvolvimento desses tumores. A compreensão da persistência do VEB no organismo e dos mecanismos pelos quais, na sua interação com a célula, ele contribui para o surgimento de uma neoplasia pode permitir novas abordagens para a prevenção e o tratamento dos tumores a ele associados.

Infections as a whole are associated with 15% to 20% of human cancers. Amongst a variery of infectious agents, oncogenic viruses are of especial importance, particularly the Epstein-Barr virus (EBV). It is the most efficient vírus known to induce transformation and cellular growth and induces immortality of B-cells. Its relation to Burkitt's lymphoma and nasopharyngeal carcinoma, as well as to other neoplasms, has long been emphazised. However, it is not clear whether it actually plays a causative role in these tumors or is simply an incidental finding. A better understanding of the means of EBV persistence and of the mechanisms by which this vírus leads to malignant transformation of the host-cell may shed light on new approaches to the prevention and treatment of EBV-associated tumors.