Chemokines and cytokines (chemo/cytokines) are proteins and peptides used for cell signaling. Primarily secreted by T cells and macrophages, they influence cellular activation, differentiation, and function and act as mediators for inflammatory and immune responses.(9) There has been substantial research linking some of these chemo/cytokines (TNFα, PDGF, TGFβ, Il-6,and IL-8) to tumor promotion and progression. For example, TNFα has been linked to greater cell survival despite genomic injury which in turn leads to greater genetic alterations and malignant transformation. TNFα has been associated with breast cancer progression and metastases.(10) Blocking the receptor for PDGF appears to decrease the metastatic potential of breast cancer cell lines.(11, 12) TGFβ inhibits T cell and B cell lymphocytes and natural killer cell cytotoxicity.(13) This immuno-suppression has been shown to promote tumor progression in mammary cancer cells lines.(13, 14) The ability of TGFβ to promote tumor progression is so well recognized that it has become a therapeutic target by some researchers.(15, 16) IFNγ has been shown to inhibit mammary cancer cell proliferation and angiogenesis in vitro and in vivo.(17) Clinically, Lyon et al reported significantly higher circulating levels of TNFα, Il-6, and IL-8 in women with breast cancer compared to women with a negative breast biopsy.(18) Additionally, researchers have directly correlated increased levels of IL-6 with the development and progression of breast cancer, and decreased overall survival (OAS).(19) Conclusion: Expression of certain chemokines and cytokines is associated with development and progression of breast cancer.