The Connection between Bacteria and Cancer: A Systematic Review of the Current Literature

Background: Outdated scientific literature claimed that bacteria was a cancerogenic agent. These studies were technically dis-favored and the hypothesis of the role of bacteria in cancer was almost completely abandoned for many years. The aim of the present study was to investigate the role of microbiome in carcinogenesis and the potential role of engineered bacteria for the treatment of cancer. Materials and Methods: The literature review was performed on Pubmed/Medline, EMBASE, Google Scholar database in accordance to the PRISMA Guidelines. The screening, and eligibility session was performed to conduct the data synthesis of the included studies. Results: The screening process included a total of 415 papers, while 389 articles were considered for the eligibility session. A total of 334 scientific products were excluded and 55 articles were considered for the descriptive synthesis. Recent reports, however, have produced new results on the role of various microorganisms in tumors. Here, we reviewed the scientific literature on this issue in order to provide an updated organic framework on the topic. Conclusions: Although basic research studies investigated and confirmed the role of bacteria in cancer induction, maintenance and resistance to therapy, the more recent literature is oriented to modern diagnostic approaches from the basic scientific knowledge to the clinical practice. The approaches to biological and immunological onco-therapy, by natural or bioengineered bacteria, were also addressed.