Dual Nature of Relationship between Mycobacteria and Cancer.

Although the therapeutic effect of mycobacteria as antitumor agents has been known for decades, recent epidemiological and experimental studies have revealed that mycobacterium-related chronic inflammation may be a possible mechanism of cancer pathogenesis. Mycobacterium tuberculosis and non-tuberculous Mycobacterium avium complex infections have been implicated as potentially contributing to the etiology of lung cancer, whereas Mycobacterium ulcerans has been correlated with skin carcinogenesis. The risk of tumor development with chronic mycobacterial infections is thought to be a result of many host effector mechanisms acting at different stages of oncogenesis. In this paper, we focus on the nature of the relationship between mycobacteria and cancer, describing the clinical significance of mycobacteria-based cancer therapy as well as epidemiological evidence on the contribution of chronic mycobacterial infections to the increased lung cancer risk.