On entering the circulation after cellular stress, cell-free mtDNA may trigger detrimental pro-inflammatory responses by inducing factors such as IL-6 [21], which maintains immune tolerance through its ability to attenuate intratumoural activity of helper and cytotoxic T cells [40, 41] and is regarded a main mediator and representative cytokine of cancer inflammation [41, 42]. This evidence concerns the gene IL6 and cancer.