IL1B and breast cancer: Moreover, leptin and IL-1 could have synergistic functions in breast cancer progression promoting VEGF/VEGFR2 expression (Gonzalez et al, 2006; Rene Gonzalez et al, 2009; Gonzalez-Perez et al, 2010) and tumour macrophage recruitment (Cao et al, 2001) that could indirectly augment leptin-mediated angiogenic effects and breast cancer growth.