Bovine leukemia virus (BLV) and risk of breast cancer; a systematic review and meta-analysis.

Background: The role of viruses in the development of breast cancer has been a subject of debate and extensive research over the past few decades. Several studies have examined the association between Bovine leukemia virus (BLV) infection and the risk of developing breast cancer; however, their findings have yielded inconsistent results. To address this uncertainty, the purpose of the present study was to conduct a systematic review and meta-analysis to determine any potential association between BLV and breast cancer.

Methods: The literature search was performed by finding related articles from PubMed, Web of Science, Scopus, EMBASE, and ScienceDirect databases. Statistical analysis was conducted using the meta package in R Studio and Review Manager 5.1. The I² test was used to assess between-study heterogeneity. The Mantel-Haenszel method calculated the pooled odds ratio and its 95% confidence interval. Studies were divided into subgroups for comparison.

Results: The literature search identified a total of 17 studies that were deemed suitable for inclusion in the systematic review. Out of these 17 studies, 12 were used in the subsequent meta-analysis. Combining the data from these eligible studies, we calculated the pooled multi-factor adjusted odds ratio (OR) and a 95% confidence interval (CI). Considering the heterogeneity observed across the studies, the result obtained using the fixed effects model was 2.12 (1.77, 2.54). However, upon removing the six studies that contributed significantly to the heterogeneity, the pooled OR with a 95% CI was recalculated to be 3.92 (2.98, 5.16).

Conclusion: The result of this study suggests that BLV infection is statistically associated with Breast cancer.