IL6 and breast cancer: Several studies have documented increased inflammation markers post breast cancer treatment, including elevation of IL-1β, TNF-α, IL-6, soluble TNF receptor type II (sTNF-RII), IL-1 receptor antagonist (IL-1RA), soluble IL-6 receptor (sIL-6R), and C-reactive protein (CRP), with the hypothesis that peripheral inflammatory cytokines may promote signals to the central nervous system that generate symptoms of fatigue [11,26,27,28].