Abbreviated Excerpt:  ”Most breast cancer cases show low concentrations of the breast cancer type 1 susceptibility protein (BRCA1). Surprisingly, only a small number of these patients have a mutated BRCA1 gene. Studies estimated that BRCA1 and BRCA2 mutations account for less than 5% of all breast cancer cases and less than 25% of familial breast cancer patients. These low numbers are consistent across the globe. For instance, an American study showed that only 3.3% of the women diagnosed with breast cancer had a mutation in their BRCA1 gene. A British study showed that only 3% of the studied breast cancer patients had mutated BRCA1/2 genes. A genetic study, done on 204 North Indian breast cancer patients, showed that only 6 patients (2.9%) had a BRCA1/2 mutation. Similarly, low numbers have been shown in a Chinese study that identified a mutation in the BRCA1/2 genes in only 7 out of 645 (1.1%) of the women with breast cancer.

Although the observed decrease in BRCA1 gene expression in the majority of the non-heritable or sporadic breast cancer cases is of great interest to the scientific and medical community, the cause is still unknown. In this paper, we use the Microcompetition Model to show how certain latent viruses, which are frequently detected in breast cancer, can decrease the expression of the BRCA1 gene and cause the development of breast tumors……. Studies also found Epstein Barr Virus (EBV) in breast cancer patients. One European study, which included 196 breast cancer specimens, found EBV DNA in 33.2% of the cases using real-time quantitative PCR (real-time PCR). Interestingly, the EBV-positive breast cancers tended to be tumors with a more aggressive phenotype. These EBV-positive tumors were also more frequently estrogen receptor negative and had a higher histological grade. A large meta-analysis of 24 studies, which included 1535 cases from all over the world, found an EBV infection in 29.3% of the patients with breast cancer. Also, patients with a positive EBV status showed a significant increase in breast malignancy risk. These studies provide evidence that EBV is statistically associated with an increased risk of breast cancer, especially of some specific types of breast cancer, such as lobular breast carcinoma . …..”

Polansky H and Schwab H: How latent viruses cause breast cancer: An explanation based on the microcompetition model. Bosn. J. Basic Med. Sci. 19(3): 221-226 (2019).


Abstract:An association of Epstein-Barr virus (EBV) infection with breast carcinoma (BC) risk has so far been disputed in the literature. Therefore, we performed a meta-analysis to clarify this relationship. An electronic database search for eligible case-control studies was performed using PubMed, Embase, Web of Science, the Cochrane Library, CNKI, and Wanfang Data until May 17, 2018. The pooled OR and 95% CI were used to estimate the relationship between EBV infection and BC risk using a fixed or random-effects model depending on heterogeneity. Subgroup analysis and meta-regression were used to explore the heterogeneity. Publication bias was assessed using Egger’s and Harbord’s tests. A total of 16 studies with 1,279 patients and 814 controls were reviewed based on our inclusion and exclusion criteria. Compared with the control group, EBV infection had a significant association with BC risk (OR 4.75, 95% CI 2.53-8.92, p < 0.01) with significant heterogeneity observed (I2 = 65.3%). The subgroup analysis revealed that region and tissue type might explain potential sources of heterogeneity. The sensitivity analyses yielded stable results. No significant publication bias was observed. The current results suggest that EBV infection is significantly associated with increased risk of BC.”

Jin Q, Su J, Yan D, Wu S. Epstein-Barr Virus Infection and Increased Sporadic Breast Carcinoma Risk: A Meta-Analysis. Med Princ Pract. 2020;29(2):195-200. doi: 10.1159/000502131. Epub 2019 Jul 17. PMID: 31311020; PMCID: PMC7098296.



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