A Potential Oncoprotective Role of Cytomegalovirus Against Breast Cancer: Worldwide Correlation and Survey of Evidence

Abstract

Introduction: While not considered a genuine tumorigenic pathogen, the human cytomegalovirus (CMV) has been associated with a wide assortment of malignancies, including breast cancer (BC). In recent years, increasing evidence has been detailing the potential anti-oncogenic capabilities of CMV. Works in the literature addressing the issue are scarce, and a global approach elucidating the role of CMV in breast cancer is lacking. Aim: We inquired into the association between CMV and BC on a global level and surveyed the related literature. Material and Methods: Virus–tumor interaction was examined by correlating country-specific CMV seroprevalence and the age-standardized BC incidence rates for 73 countries, as provided by the International Agency for Research on Cancer (IARC). Statistical analysis was conducted using Spearman’s correlation, along with univariate and multivariate linear regression analysis. The literature review included works available in the PubMed® database until and including February 2025. Results: The worldwide incidence of BC correlated strongly and inversely with CMV prevalence the world over (p < 0.001, Spearman ρ = −0.553). This association was upheld after univariate and multivariate linear regression, extending to other tumors such as skin melanoma and kidney cancer (p < 0.001). Conclusions: In this study, we draw attention to a previously unexplored global inverse relationship between the prevalence of CMV and the incidence of BC, which suggests a potential oncoprotective role for this pathogen. Although the association itself does not imply causality, these data provide an intriguing possibility of observing CMV as a tentative factor of protection against this malignancy.