Epstein-Barr Virus Infection and Risk of Breast Cancer: An Adaptive Meta-Analysis for Case-Control Studies

authors:

avatar Jong-Myon Bae 1 , * , avatar Eun Hee Kim 1

Department of Preventive Medicine, Jeju National University School of Medicine, Jeju-do, Korea

how to cite: Bae J, Kim E H. Epstein-Barr Virus Infection and Risk of Breast Cancer: An Adaptive Meta-Analysis for Case-Control Studies. Arch Clin Infect Dis. 2016;11(3):e34806. https://doi.org/10.5812/archcid.34806.

Abstract

Context:

The association between 'Epstein-Barr' virus (EBV) and breast cancer risk still remains controversial. A Systemic Review (SR) published in 2012 reported that there might be a statistically significant association between EBV and risk of breast cancer. However, errors were found in the appraisal process of the concerned SR.

Objectives:

The aim of this report was to conduct an adaptive meta-analysis with additional extraction of relevant papers published up until September 2015.

Data Sources:

The lists of references, cited articles and related articles provided by PubMed were made using the articles selected in the previous SR.

Study Selection:

Among these articles, only case-control studies using Polymerase Chain Reaction (PCR) techniques to detect EBV DNA in tissues were selected.

Data Extraction:

The summary odds ratio (SOR) and the 95% confidence interval (CI) were calculated though meta- analysis.

Results:

A total of 20 case-control studies were selected, and the total numbers of subjects in the case and control groups were 1947 and 1010, respectively. The findings of this meta-analysis revealed that EBV infection might increase the risk of breast cancer (SOR = 3.84, 95% CI: 2.24-6.58; I-squared = 62.2%). Sub-group analyses by region, sample type, and control tissue showed that a statistical significance of the risk was still secured.

Conclusions:

The findings of the meta-epidemiological study support that EBV infection may increase the risk of breast cancer. Nested case-control studies are required in the future.

1. Context

Globally, breast cancer is the most frequent primary cancer among women (1). However, about half of breast cancer cases occur in economically developing countries, in young age groups (2, 3). Such an epidemiological characteristic cannot be fully explained by known risk factors (4, 5).

Virus infection is known to cause about 15% of all cancers (6), and Epstein-Barr Virus (EBV) is ‘the first human tumor virus’ (7), which belongs to group-1 carcinogen (8) with association with various cancers including Burkitt lymphoma, nasopharyngeal carcinoma, and Hodgkin’s disease (9, 10). Since the proposal of the association between breast cancer and EBV in 1995 by Labrecque et al. (11), it has remained controversial to date (12). Incidentally, in order to meet the criteria required to demonstrate that a specific virus may cause cancer (13, 14), a case-control study instead of a case study is required (15). However, tumor-based case-control study using cancer tissues has a drawback of making measurement errors (14, 16). In order to overcome the limitations, a systematic review (SR) is considered necessary.

Huo et al. (17) performed a SR on 10 case-control studies published up to September 2010 and reported a 6.8-fold (95% confidence intervals, CI: 2.13-18.59) increased risk of breast cancer with EBV infection. However, looking at the forest plot that shows the results of meta-analysis of the concerned SR, we identified that the Odds Ratio (OR) value by Tsai et al. (18) contained errors, where the information of the case group and the control group were reversely entered. In addition, the two papers (19, 20) reported by the same author in 2003 and 2005 had applied an overlapping meta-analysis. The presented summary odds ratio (SOR) with these errors is likely to be overestimated than actual.

Flow Chart of Article Selection
Flow Chart of Article Selection

2. Objectives

The aim of this study was to perform an adaptive meta-analysis for examining the association between EBV infection and breast cancer by extending the publication period of articles up to September 2015.

3. Data Sources

Considering the fact that we were reanalyzing an already published SR (17), hand search strategy was applied instead of an electronic search (21-23). With an assumption that studies conducted with the same research hypothesis have a high likelihood of citing the articles included in the original SR, adaptive meta-analysis (AMA) was conducted (21-23). As the citation discovery tools such as ‘cited by’ and ‘similar’ tools in PubMed (www.ncbi.nlm.nih.gov/pubmed) is enough to conduct an AMA (21), the list of “cited articles” and “similar articles” from PubMed of each article, selected by Huo et al. (17), was secured. The publication period of articles included in the list was until September 2015.

4. Study Selection

The inclusion criteria were case-control studies, which met the criteria set by Huo et al. (17), and used tissues as samples and polymerase chain reaction (PCR) for EVB-DNA detection in tissues. Therefore, based on the titles and abstracts of the combined lists, the following three exclusion criteria were primarily applied for the final selection: different hypothesis, expert reviews or systematic reviews, and case only studies. For the remaining case-control studies, the following conditions were excluded: (1) if there were no EBV DNA positive subjects in both the case group and the control group, (2) when the samples were not tissues, (3) when PCR techniques were not used and (4) when duplicate samples were reported. After applying the above seven exclusion criteria, the remaining case-control studies were selected for the final analysis.

5. Data Extraction and Analysis

The application of the exclusion criteria for each article, and EBV-related information, including, the number of detection tests and the number of positive DNA diagnoses in each of the subject and control groups, nationality of the subjects, type of sample, and kind of control tissue, were processed by two researchers. As the selected articles were case-control studies dealing with DNA detection, the appraisal of quality of evidence was not conducted. The OR and 95% CI for each study was calculated by utilizing the number of EBV DNA positive and negative diagnoses in case and control groups. The region was categorized into Arabia, North Africa and Europe, North America, and other regions using nationality. The samples were divided to two groups of paraffin-embedded tissue (PET) and fresh frozen tissue (FFT). The control tissues were divided into adjacent non-cancer tissue (ANT) and normal tissue (NT).

Heterogeneity across the studies for performing meta-analysis was assessed based on the I-squared value (%). The SOR and its 95% CI, according to the random effect model were primarily obtained. Egger’s test for small-study effects was performed to examine publication bias (24). In the presence of a publication bias, sensitivity analysis was performed only when the standard error of logarithm OR (s.e. log OR) in the funnel plot was less than one. Statistical significance was set at 5%, and STATA version 14 (www.stata.com) was used for the analysis.

6. Results

Figure 1 shows the flow chart of article selection for meta-analysis through data retrieval from the database. Lists of 58 references and 299 cited or related articles by PubMed on the basis of SR (17), to determine the level of breast cancer risk, were acquired. When the exclusion criteria were applied to the total of 357 articles, 32 case-control studies were selected. Among these, (1) three studies in which EBV-DNA was not detected in both the subject and the control group (25-27), (2) six studies in which the samples were not tissues (28-33), (3) two studies not using PCR (34, 35), and (4) one study that used duplicate samples (20) were excluded.

Forest Plot of Random-Effects Summary Estimates by Global Area in 20 Case-Control Studies ES: Effect Size (= Summary Odds Ratio); CI: Confidence Interval
Forest Plot of Random-Effects Summary Estimates by Global Area in 20 Case-Control Studies ES: Effect Size (= Summary Odds Ratio); CI: Confidence Interval

A total of 20 studies were finally selected for meta-analysis through the above-mentioned exclusion process (11, 18, 36-53). Table 1 shows a summary of the EBV-DNA positive subjects according to nationality, types of sample, and kinds of control tissue in the 20 selected studies. From the results of Bonnet et al. (37), two specimens of male breast cancer patients were excluded. Accordingly, from a total of 20 case-control studies, 1947 were cases and 1010 were controls. When sorted by region, there were seven studies in Northern Africa and Europe, six studies in Arabia, and six studies in other regions. When sorted by the types of samples, there were nine studies using paraffin-embedded tissue (PET), nine studies using fresh frozen tissue (FFT), and two studies using both. And there were eight studies using adjacent non-cancer tissue (NAT), 11 studies using normal tissue (NT), and one study using both, in control tissues.

Table 1.

Summary of the Twenty Case-Control Studies

Author (year) [Ref]NationSpecimenControl TissueAmplification Fragments in PCRCase (n/N)Control (n/N)OR (95% CI)
Labrecque (1995) (11)UKFFTNTBamHIW19/910/2111.57 (0.67, 199.55)
Luqmani (1995) (36)UKPETNTBamHIW15/280/1223.48 (1.28, 431.34)
Bonnet (1999) (37)FranceFFTNATBamHIW51/983/309.77 (2.78, 34.32)
Fina (2001) (38)Africa, EuropeFFT/PETNT/NATBamHIC162/5090/109.82 (0.54, 177.18)
McCall (2001) (39)USPETNTEBNA11/1156/2780.40 (0.05, 3.34)
Grinstein (2002) (40)USPETNTEBNA114/333/265.65 (1.41, 22.61)
Huang (2003) (41)USFFTNATBamHIW7/104/103.50 (0.55, 22.30)
Kalkan (2005) (42)TurkeyPETNATGp22013/5719/550.56 (0.24, 1.29)
Tsai (2005) (18)TaiwanFFTNTBamHIW28/6216/320.82 (0.35, 1.94)
Mohamed (2007) (43)EgyptPETNATLMP112/346/342.55 (0.82, 7.86)
Fawzy (2008) (44)EgyptPETNTBamHIW8/400/2010.72 (0.59, 195.91)
Lorenzetti (2010) (45)ArgentinaPETNTEBNA122/710/4844.09 (2.60, 747.28)
Hachana (2011) (46)TunisiaFFTNATBamHIG33/1230/12391.43 (5.53, 1511.83)
Mazouni (2011) (47)FranceFFTNTBamHIC65/1961/156.95 (0.89, 53.99)
Glenn (2012) (48)AustraliaFFTNTEBNA134/5014/401.94 (0.92, 4.11)
Khabaz (2012) (49)Saudi ArabiaPETNTEBNA124/923/495.41 (1.54, 19.02)
Zekri (2012) (50)Egypt, IraqPETNTEBNA132/900/2022.78 (1.33, 389.09)
Marales-Sanchez (2013) (51)MexicoFFT/PETNATBamHIW4/860/657.15 (0.38, 135.13)
Yahia (2014) (52)SudanFFTNATEBNA449/9212/503.61 (1.68, 7.77)
Richardson (2015) (53)New ZealandFFTNATEBNA124/709/703.54 (1.50, 8.33)

When a meta-analysis with random-effect model was performed for the 20 studies, the risk of breast cancer (SOR) based on EBV DNA positive detection showed a 3.84-fold increase (95% CI: 2.24 - 6.58: I-squared = 62.2%) (Figure 2). The results of the Egger test to examine publication bias indicated a bias coefficient of 2.01 and a standard error of 0.64, showing statistical significance (P = 0.006) (Figure 3). As publication bias was identified, sensitivity analysis was performed for the ten studies with s.e. log OR value of less than 1.0 in the Funnel plot. The Egger test resulted in a bias coefficient of 3.05 and a standard error of 2.04 without statistical significance (P = 0.17), while the SOR was 2.57-fold (95% CI: 1.46 - 4.51: I-squared = 67.6%), still having statistical significance.

The Funnel Plot
Log OR, logarithm odds ratio; s.e., P value of Egger’s test (= 0.006).

The results of sub-group analysis by region, types of tissue sample, and kinds of control tissues are summarized in Table 2. By region, the SOR was 4.43 folds (95% CI: 2.04 - 9.62) in the Arabia region and 7.37 folds (95% CI: 3.65 - 14.86) in the Northern Africa and Europe region. By tissue sample, it was 3.97 folds in PET (95% CI: 1.40 - 11.22), 3.67 folds in FFT (95% CI: 1.90 - 7.12); all showing statistical significances. Both SORs of NAT and NT showed statistical significances.

Table 2.

Sub-Group Analysis by Area, Type of Tissue, Kind of Control Tissues and the Standard Error of Logarithm Odds Ratio (s.e. log oR)

Number of ArticlesReferenceI-Squared (%)SOR (95% CI)
Overall20(11, 18, 36-53)62.23.84 (2.24, 6.58)
Arabia4(43, 44, 49, 50)0.04.43 (2.04, 9.62)
North Africa & Europe7(11, 36-38, 46, 47, 52)14.87.37 (3.65, 14.86)
North America3(39-41)53.22.34 (0.53, 10.37)
Others6(18, 42, 45, 48, 51, 53)72.51.90 (0.80, 4.51)
PET9(36, 39, 40, 42-45, 49, 50)70.73.97 (1.40, 11.22)
FFT9(11, 18, 37, 41, 46-48, 52, 53)61.93.67 (1.90, 7.12)
PET and FFT2(38,51)0.08.40 (1.07, 66.02)
NAT8(37, 41-43, 46, 51-53)72.33.63 (1.58, 8.35)
NT11(11, 18, 36, 39, 40, 44, 45, 47-50)58.64.05 (1.84, 8.95)
NAT and NT1(38)--
s.e. log OR < 110(18, 37, 40-43, 48, 49, 52, 53)67.62.57 (1.46, 4.51)

7. Discussion

Meta-analysis of the 20 case-control studies revealed that the risk of breast cancer associated with EBV infection was 3.84 folds higher (95% CI: 2.24 - 6.58). In the sensitivity analysis of the ten studies, with s.e. log OR of less than one, and with regards to possible publication bias, the results still showed statistical significance. The aforementioned risk was lower than the SOR of 6.29 reported by Huo et al. (17), but as it was entirely included in the proposed 95% confidence interval (2.13 - 18.59), it can be interpreted that the estimated risk had become more accurate. In other words, the strong point of this updated SR was that it calculated a more accurate effect size.

By region, statistical significance was found in Arabia, North Africa and Europe, but not in North America and other regions. However, the number of related articles was small in the regions where a statistical significance was not obtained, and as the I-squared values was all above 50%, it is difficult to conclude that the risk of EBV may differ depending on region. The two regions showing statistical significance, had concerned articles of 4 and 7 each, and there was homogeneity in terms of the I-squared values (Table 2). Meanwhile, considering that the regions showing high statistical significance in this SR were Mediterranean-neighboring countries known to have high EBV prevalence, it may be interpreted that the risk of breast cancer could alter depending on EBV prevalence by region (5, 17).

Sub-group analysis was performed by dividing the samples into PET and FFT and both, but all showed statistical significances, and SORs were found to be similar. These results indicate that despite the controversial DNA detection of human papillomavirus (54, 55), it was not a problem for EBV DNA detection (13, 17). The subgroup analysis by types of control tissue also showed the same findings.

The main problems that have caused the controversy about the association between EBV infection and breast cancer were that the impact of the aforementioned EBV prevalence level not being considered and that the experimental methodology of EBV has not been standardized (5, 17, 34, 56). Several kinds of tests for EBV detection have been developed (57). While PCR shows a high sensitivity and specificity for the detection methods (5), Immunohistochemistry (IHC) shows a low degree of accuracy (17). Therefore, the two case-control studies adopting the IHC method (34, 35) were excluded from the selection of studies for SR.

The hand searching strategy with AMA was applied rather than electronic searching in this SR (21). As a result, four articles could be additionally identified (36, 39, 41, 43), which should have been included in the SR by Huo et al. (17) who performed an electronic search for articles published up to September 2010. Furthermore, an additional nine case-control studies published (45-53) thereafter were additionally acquired. The lists of 20 case-control studies selected for this SR may be utilized as an important list for additional adaptive meta-analyses in the future.

Various evidence for the association between EBV and breast cancer has been presented (44, 50). Such evidence may provide opportunities for the pathogenesis, early detection and prevention of breast cancer (5, 58, 59). In particular, along with the reports of worse prognosis of EBV DNA positive patients than the negative patients (12, 34, 37), this can be applied to the treatment of breast cancer.

In conclusion, the results of SR on the 20 case-control studies support that EBV infection may increase the risk of breast cancer. In order to reduce further controversy, case-control studies that more strictly match by type of tissues and detection method are required in the future. For such studies, frozen samples through cohort construction should be used in nested case-control studies in the future.

References

  • 1.

    Torre LA, Bray F, Siegel RL, Ferlay J, Lortet-Tieulent J, Jemal A. Global cancer statistics, 2012. CA Cancer J Clin. 2015;65(2):87-108. [PubMed ID: 25651787]. https://doi.org/10.3322/caac.21262.

  • 2.

    Jemal A, Bray F, Center MM, Ferlay J, Ward E, Forman D. Global cancer statistics. CA Cancer J Clin. 2011;61(2):69-90. [PubMed ID: 21296855]. https://doi.org/10.3322/caac.20107.

  • 3.

    Curado MP. Breast cancer in the world: incidence and mortality. Salud Publica Mex. 2011;53(5):372-84. [PubMed ID: 22218791].

  • 4.

    Dumitrescu RG, Cotarla I. Understanding breast cancer risk -- where do we stand in 2005? J Cell Mol Med. 2005;9(1):208-21. [PubMed ID: 15784178].

  • 5.

    Glaser SL, Hsu JL, Gulley ML. Epstein-Barr virus and breast cancer: state of the evidence for viral carcinogenesis. Cancer Epidemiol Biomarkers Prev. 2004;13(5):688-97. [PubMed ID: 15159298].

  • 6.

    Wong M, Pagano JS, Schiller JT, Tevethia SS, Raab-Traub N, Gruber J. New associations of human papillomavirus, Simian virus 40, and Epstein-Barr virus with human cancer. J Natl Cancer Inst. 2002;94(24):1832-6. [PubMed ID: 12488476].

  • 7.

    Javier RT, Butel JS. The history of tumor virology. Cancer Res. 2008;68(19):7693-706. [PubMed ID: 18829521]. https://doi.org/10.1158/0008-5472.CAN-08-3301.

  • 8.

    Epstein-Barr Virus. IARC Monographs-100B. Available from: http://monographs.iarc.fr/ENG/Monographs/vol100B/mono100B-6.pdf.

  • 9.

    Murray PG, Young LS. The Role of the Epstein-Barr virus in human disease. Front Biosci. 2002;7:d519-40. [PubMed ID: 11815292].

  • 10.

    Hsu JL, Glaser SL. Epstein–Barr virus-associated malignancies: epidemiologic patterns and etiologic implications. Critical Revi Oncol Hematol. 2000;34(1):27-53.

  • 11.

    Labrecque LG, Barnes DM, Fentiman IS, Griffin BE. Epstein-Barr virus in epithelial cell tumors: a breast cancer study. Cancer Res. 1995;55(1):39-45. [PubMed ID: 7805038].

  • 12.

    Amarante MK, Watanabe MA. The possible involvement of virus in breast cancer. J Cancer Res Clin Oncol. 2009;135(3):329-37. [PubMed ID: 19009309]. https://doi.org/10.1007/s00432-008-0511-2.

  • 13.

    De Paoli P, Carbone A. Carcinogenic viruses and solid cancers without sufficient evidence of causal association. Int J Cancer. 2013;133(7):1517-29. [PubMed ID: 23280523]. https://doi.org/10.1002/ijc.27995.

  • 14.

    Joshi D, Buehring GC. Are viruses associated with human breast cancer? Scrutinizing the molecular evidence. Breast Cancer Res Treat. 2012;135(1):1-15. [PubMed ID: 22274134]. https://doi.org/10.1007/s10549-011-1921-4.

  • 15.

    Liang W, Tian H. Hypothetic association between human papillomavirus infection and breast carcinoma. Med Hypotheses. 2008;70(2):305-7. [PubMed ID: 17656036]. https://doi.org/10.1016/j.mehy.2007.05.032.

  • 16.

    Engels EA, Wacholder S, Katki HA, Chaturvedi AK. Tumor-based case-control studies of infection and cancer: muddling the when and where of molecular epidemiology. Cancer Epidemiol Biomarkers Prev. 2014;23(10):1959-64. [PubMed ID: 25063520]. https://doi.org/10.1158/1055-9965.EPI-14-0282.

  • 17.

    Huo Q, Zhang N, Yang Q. Epstein-Barr virus infection and sporadic breast cancer risk: a meta-analysis. PLoS One. 2012;7(2):31656. [PubMed ID: 22363698]. https://doi.org/10.1371/journal.pone.0031656.

  • 18.

    Tsai JH, Tsai CH, Cheng MH, Lin SJ, Xu FL, Yang CC. Association of viral factors with non-familial breast cancer in Taiwan by comparison with non-cancerous, fibroadenoma, and thyroid tumor tissues. J Med Virol. 2005;75(2):276-81. [PubMed ID: 15602723]. https://doi.org/10.1002/jmv.20267.

  • 19.

    Preciado MV. Lack of evidence for an association of Epstein–Barr virus infection with breast carcinoma-another point of view. Breast Cancer Res. 2003;5(4):E6.

  • 20.

    Preciado MV, Chabay PA, De Matteo EN, Gonzalez P, Grinstein S, Actis A, et al. Epstein-Barr virus in breast carcinoma in Argentina. Arch Pathol Lab Med. 2005;129(3):377-81. [PubMed ID: 15737034]. https://doi.org/10.1043/1543-2165(2005)129<377:EVIBCI>2.0.CO;2.

  • 21.

    Bae JM, Kim EH. Citation Discovery Tools for Conducting Adaptive Meta-analyses to Update Systematic Reviews. J Prev Med Public Health. 2016;49(2):129-33. [PubMed ID: 27055549]. https://doi.org/10.3961/jpmph.15.074.

  • 22.

    Bae JM, Kim EH. Epstein-Barr Virus and Gastric Cancer Risk: A Meta-analysis With Meta-regression of Case-control Studies. J Prev Med Public Health. 2016;49(2):97-107. [PubMed ID: 27055546]. https://doi.org/10.3961/jpmph.15.068.

  • 23.

    Bae JM, Kim EH. Human papillomavirus infection and risk of breast cancer: a meta-analysis of case-control studies. Infect Agent Cancer. 2016;11:14. [PubMed ID: 26981149]. https://doi.org/10.1186/s13027-016-0058-9.

  • 24.

    Harbord RM, Egger M, Sterne JA. A modified test for small-study effects in meta-analyses of controlled trials with binary endpoints. Stat Med. 2006;25(20):3443-57. [PubMed ID: 16345038]. https://doi.org/10.1002/sim.2380.

  • 25.

    Chang KL, Chen YY, Shibata D, Weiss LM. Description of an in situ hybridization methodology for detection of Epstein-Barr virus RNA in paraffin-embedded tissues, with a survey of normal and neoplastic tissues. Diagn Mol Pathol. 1992;1(4):246-55. [PubMed ID: 1342973].

  • 26.

    Kadivar M, Monabati A, Joulaee A, Hosseini N. Epstein-Barr virus and breast cancer: lack of evidence for an association in Iranian women. Pathol Oncol Res. 2011;17(3):489-92. [PubMed ID: 21207256]. https://doi.org/10.1007/s12253-010-9325-z.

  • 27.

    Perrigoue JG, den Boon JA, Friedl A, Newton MA, Ahlquist P, Sugden B. Lack of association between EBV and breast carcinoma. Cancer Epidemiol Biomarkers Prev. 2005;14(4):809-14. [PubMed ID: 15824148]. https://doi.org/10.1158/1055-9965.EPI-04-0763.

  • 28.

    Cox B, Richardson A, Graham P, Gislefoss RE, Jellum E, Rollag H. Breast cancer, cytomegalovirus and Epstein-Barr virus: a nested case-control study. Br J Cancer. 2010;102(11):1665-9. [PubMed ID: 20407437]. https://doi.org/10.1038/sj.bjc.6605675.

  • 29.

    He JR, Tang LY, Yu DD, Su FX, Song EW, Lin Y, et al. Epstein-Barr virus and breast cancer: serological study in a high-incidence area of nasopharyngeal carcinoma. Cancer Lett. 2011;309(2):128-36. [PubMed ID: 21724319]. https://doi.org/10.1016/j.canlet.2011.05.012.

  • 30.

    He JR, Chen LJ, Su Y, Cen YL, Tang LY, Yu DD, et al. Joint effects of Epstein-Barr virus and polymorphisms in interleukin-10 and interferon-gamma on breast cancer risk. J Infect Dis. 2012;205(1):64-71. [PubMed ID: 22095765]. https://doi.org/10.1093/infdis/jir710.

  • 31.

    Qi ML, Xi J, Chen LJ, Su Y, Cen YL, Su FX, et al. Association of Epstein-Barr virus and passive smoking with the risk of breast cancer among Chinese women. Eur J Cancer Prev. 2014;23(5):405-11. [PubMed ID: 25010836]. https://doi.org/10.1097/CEJ.0000000000000071.

  • 32.

    Viljoen J, Tuaillon E, Nagot N, Danaviah S, Peries M, Padayachee P, et al. Cytomegalovirus, and possibly Epstein-Barr virus, shedding in breast milk is associated with HIV-1 transmission by breastfeeding. AIDS. 2015;29(2):145-53. [PubMed ID: 25535751]. https://doi.org/10.1097/QAD.0000000000000527.

  • 33.

    Glenn WK, Whitaker NJ, Lawson JS. High risk human papillomavirus and Epstein Barr virus in human breast milk. BMC Res Notes. 2012;5:477. [PubMed ID: 22937830]. https://doi.org/10.1186/1756-0500-5-477.

  • 34.

    Mohammadizadeh F, Zarean M, Abbasi M. Association of Epstein-Barr virus with invasive breast carcinoma and its impact on well-known clinicopathologic parameters in Iranian women. Adv Biomed Res. 2014;3:141. [PubMed ID: 25161988]. https://doi.org/10.4103/2277-9175.135158.

  • 35.

    Joshi D, Quadri M, Gangane N, Joshi R, Gangane N. Association of Epstein Barr virus infection (EBV) with breast cancer in rural Indian women. PLoS One. 2009;4(12):8180. [PubMed ID: 19997605]. https://doi.org/10.1371/journal.pone.0008180.

  • 36.

    Luqmani YA, Shousha S. Presence of Epstein-Barr-Virus in Breast-Carcinoma. Int J Oncol. 1995. https://doi.org/10.3892/ijo.6.4.899.

  • 37.

    Bonnet M, Guinebretiere JM, Kremmer E, Grunewald V, Benhamou E, Contesso G, et al. Detection of Epstein-Barr virus in invasive breast cancers. J Natl Cancer Inst. 1999;91(16):1376-81. [PubMed ID: 10451442].

  • 38.

    Fina F, Romain S, Ouafik LH, Palmari J, Ayed FB, Benharkat S, et al. Frequency and genome load of Epstein–Barr virus in 509 breast cancers from different geographical areas. British J Cancer. 2001;84(6):783-90. https://doi.org/10.1054/bjoc.2000.1672.

  • 39.

    McCall SA, Lichy JH, Bijwaard KE, Aguilera NS, Chu WS, Taubenberger JK. Epstein-Barr virus detection in ductal carcinoma of the breast. J Natl Cancer Inst. 2001;93(2):148-50. [PubMed ID: 11208885].

  • 40.

    Grinstein S, Preciado MV, Gattuso P, Chabay PA, Warren WH, De Matteo E, et al. Demonstration of Epstein-Barr virus in carcinomas of various sites. Cancer Res. 2002;62(17):4876-8. [PubMed ID: 12208733].

  • 41.

    Huang J, Chen H, Hutt-Fletcher L, Ambinder RF, Hayward SD. Lytic viral replication as a contributor to the detection of Epstein-Barr virus in breast cancer. J Virol. 2003;77(24):13267-74. [PubMed ID: 14645583].

  • 42.

    Kalkan A, Ozdarendeli A, Bulut Y, Yekeler H, Cobanoglu B, Doymaz MZ. Investigation of Epstein-Barr virus DNA in formalin-fixed and paraffin- embedded breast cancer tissues. Med Princ Pract. 2005;14(4):268-71. [PubMed ID: 15961939]. https://doi.org/10.1159/000085748.

  • 43.

    Mohamed WS, Mohamed MA, Omar MM. Possible involvement of Epstein-barr Virus (EBV) in pathogenesis and prognosis of female breast infiltrating duct carcinoma: clinicopathological, immunohistochemical and molecular study. The Egy J Med Microbiol. 2007;16(2):403-14.

  • 44.

    Fawzy S, Sallam M, Awad NM. Detection of Epstein-Barr virus in breast carcinoma in Egyptian women. Clin Biochem. 2008;41(7-8):486-92. [PubMed ID: 18258188]. https://doi.org/10.1016/j.clinbiochem.2007.12.017.

  • 45.

    Lorenzetti MA, De Matteo E, Gass H, Martinez Vazquez P, Lara J, Gonzalez P, et al. Characterization of Epstein Barr virus latency pattern in Argentine breast carcinoma. PLoS One. 2010;5(10):13603. [PubMed ID: 21042577]. https://doi.org/10.1371/journal.pone.0013603.

  • 46.

    Hachana M, Amara K, Ziadi S, Romdhane E, Gacem RB, Trimeche M. Investigation of Epstein-Barr virus in breast carcinomas in Tunisia. Pathol Res Pract. 2011;207(11):695-700. [PubMed ID: 22024152]. https://doi.org/10.1016/j.prp.2011.09.007.

  • 47.

    Mazouni C, Fina F, Romain S, Ouafik L, Bonnier P, Brandone JM, et al. Epstein-Barr virus as a marker of biological aggressiveness in breast cancer. Br J Cancer. 2011;104(2):332-7. [PubMed ID: 21179039]. https://doi.org/10.1038/sj.bjc.6606048.

  • 48.

    Glenn WK, Heng B, Delprado W, Iacopetta B, Whitaker NJ, Lawson JS. Epstein-Barr virus, human papillomavirus and mouse mammary tumour virus as multiple viruses in breast cancer. PLoS One. 2012;7(11):48788. [PubMed ID: 23183846]. https://doi.org/10.1371/journal.pone.0048788.

  • 49.

    Khabaz MN. Association of Epstein-Barr virus infection and breast carcinoma. Arch Med Sci. 2013;9(4):745-51. [PubMed ID: 24049539]. https://doi.org/10.5114/aoms.2013.37274.

  • 50.

    Zekri AR, Bahnassy AA, Mohamed WS, El-Kassem FA, El-Khalidi SJ, Hafez MM, et al. Epstein-Barr virus and breast cancer: epidemiological and molecular study on Egyptian and Iraqi women. J Egypt Natl Canc Inst. 2012;24(3):123-31. [PubMed ID: 22929918]. https://doi.org/10.1016/j.jnci.2012.06.001.

  • 51.

    Morales-Sanchez A, Molina-Munoz T, Martinez-Lopez JL, Hernandez-Sancen P, Mantilla A, Leal YA, et al. No association between Epstein-Barr Virus and Mouse Mammary Tumor Virus with breast cancer in Mexican women. Sci Rep. 2013;3:2970. [PubMed ID: 24131889]. https://doi.org/10.1038/srep02970.

  • 52.

    Yahia ZA, Adam AA, Elgizouli M, Hussein A, Masri MA, Kamal M, et al. Epstein Barr virus: a prime candidate of breast cancer aetiology in Sudanese patients. Infect Agent Cancer. 2014;9(1):9. [PubMed ID: 24607238]. https://doi.org/10.1186/1750-9378-9-9.

  • 53.

    Richardson AK, Currie MJ, Robinson BA, Morrin H, Phung Y, Pearson JF, et al. Cytomegal Epstein-Barr Virus Breast Cancer. PLoS One. 2015;10(2):118989. [PubMed ID: 25723522]. https://doi.org/10.1371/journal.pone.0118989.

  • 54.

    Wang T, Chang P, Wang L, Yao Q, Guo W, Chen J, et al. The role of human papillomavirus infection in breast cancer. Med Oncol. 2012;29(1):48-55. [PubMed ID: 21318737]. https://doi.org/10.1007/s12032-010-9812-9.

  • 55.

    Li J, Ding J, Zhai K. Detection of Human Papillomavirus DNA in Patients with Breast Tumor in China. PLoS One. 2015;10(8):136050. [PubMed ID: 26295705]. https://doi.org/10.1371/journal.pone.0136050.

  • 56.

    Cedro-Tanda A, Cordova-Solis A, Juarez-Cedillo T, Pina-Jimenez E, Hernandez-Caballero ME, Moctezuma-Meza C, et al. Prevalence of HMTV in breast carcinomas and unaffected tissue from Mexican women. BMC Cancer. 2014;14:942. [PubMed ID: 25495285]. https://doi.org/10.1186/1471-2407-14-942.

  • 57.

    Gulley ML. Molecular Diagnosis of Epstein-Barr Virus-Related Diseases. J Molecul Diagnost. 2001;3(1):1-10. https://doi.org/10.1016/s1525-1578(10)60642-3.

  • 58.

    Lawson JS, Heng B. Viruses and breast cancer. Cancers (Basel). 2010;2(2):752-72. [PubMed ID: 24281093]. https://doi.org/10.3390/cancers2020752.

  • 59.

    Bae JM. Two hypotheses of dense breasts and viral infection for explaining incidence of breast cancer by age group in Korean women. Epidemiol Health. 2014;36. e2014020. [PubMed ID: 25266421]. https://doi.org/10.4178/epih/e2014020.