Bovine Leukemia virus (BLV) and risk of breast cancer: a systematic review and meta-analysis of case-control studies

Abstract

Background: Breast cancer is reported as one of the most common cancers among females worldwide. Infectious agents especially viruses have been considered as role players in the development of breast cancer. Although some investigations suggest an association between bovine leukemia virus (BLV) and breast cancer, the involvement of this virus as a risk factor remains controversial. The present study aimed to find out any possible association between BLV and breast cancer through conducting a systematic review and meta-analysis. Methods: Systematic literature search was performed by finding related case-control articles from the PubMed, Google Scholar, Web of Science, Scopus, and EMBASE databases. The heterogeneity and the multivariable-adjusted OR and corresponding 95% CI were applied by meta-analysis and forest plot across studies. All statistical analyses were performed using Stata 14.1. Result: Based on a comprehensive literature search, 9 case-control studies were included for meta-analysis. The combination of all included studies showed that BLV infection is associated with an increased risk of breast cancer [summary OR (95% CI) 2.57 (1.45, 4.56)]. Conclusion: This is the first meta-analysis to analyze a potential association between BLV infection and the risk of breast cancer. Control of the infection in cattle herds and screening of the milk and dairy products may help to reduce the transmission of the virus to humans.

Cancer risk across mammals

“…For instance, in humans it was estimated that 10–20% of all cancers are of viral origin 30 . While this figure is unknown in any other animal species 29 , it is arguable that raw meat consumption might exacerbate the spread of carcinogenic pathogens 31 . Exploring the association between diet and cancer risk could help to disentangle the influences of these risk factors.…”

Co-Circulation of Bovine Leukemia Virus Haplotypes among Humans, Animals, and Food Products: New Insights of Its Zoonotic Potential

“…In addition, evidence of BLV in human beings has been reported by different researchers via the presence of its gene segments, proteins and antibodies against the virus in different parts of the world [ 23 , 24 , 25 , 26 , 27 , 28 ]. Epidemiological studies have identified a significant association between the presence of the virus and breast cancer development, proposing BLV as an intermediate risk factor for cancer outcome [ 29 , 30 ]. Furthermore, evidence of BLV and some other viruses has also been reported in lung cancer, showing a correlation with the up and down regulation of metabolic pathways associated with cell control and oncogenesis [ 31 , 32 ].…”

The global molecular epidemiology of microsporidia infection in sheep and goats with focus on Enterocytozoon bieneusi: a systematic review and meta-analysis

“…The comprehensive meta-analysis Bio stat v2.2 software was employed for meta-analysis procedure [ 10 , 11 , 20 ]. Calculation of the pooled prevalence of microsporidia infection among small ruminants and 95% confidence intervals (CIs) was done using random-effects model (REM), which enhances the distribution of true effect sizes among studies [ 21 , 22 ]. Subgroup analysis was, also, performed in order to reveal the weighted prevalence based on continent, country, and type of ruminants (sheep and goats).…”