IL6 and breast cancer: Of the 93 studies (including 85 case-control studies, 2 cross-sectional studies and 6 cohort studies) reporting levels of adipokines levels among patients with breast cancer, 46 had evaluated leptin, 29 had evaluated adiponectin, 29 had estimated IL-6 levels, 17 had estimated TNF-α, six had evaluated resistin, and lastly, three each had evaluated HGF, PAI-1, and visfatin.