Abstract

Bacteria can participate in carcinogenesis and up to 10 bacteria, among them Helicobacter pylori, Escherichia coli and Bacteroides fragilis, are identified worldwide as carcinogenic. Factors of bacterial virulence and chronic inflammation induce DNA damage and toxins activate cellular polarity and the growth modulating Wnt/beta-catenin pathway. Bacteria- induced chronic inflammation stimulates development of cancer, due to the continuously high level of reactive oxygen species. In addition, microbes have an impact on the therapeutic efficacy and toxicity of the cancer drug. Irinotecan toxicity depends on bacterial beta-glucuronidases and cyclophosphamide efficacy is supported by Lactobacillus johnsonii and Enterococcus hirae, which are associated with naïve CD4+-cells differentiation. The microbiota has also a role in mediating the efficacy of immune checkpoint inhibitors.