BCG was originally developed as a tuberculosis vaccine more than 100 years ago, which was known as an attenuated strain of Mycobacterium bovis, and induced biologically active cytokines, such as IFN-γ and IL-2, and immune effector cells that improve tumor recognition and killing capacity through both nonspecific and specific (such as antigen-specific T cells) mechanisms [34,35]. The gene discussed is IFNG; the disease is neoplasm.