Breast cancer is the second most prominent cancer facing women today. Statistically, 1 in every 8 women in the US will develop breast cancer during their lifetime. When tumor cells metastasize to other tissues, patient prognosis becomes unfavorable. There are many several subtypes of breast cancer and the metastatic potential varies with each subtype and patient status. For example, breast cancer that is estrogen receptor positive, progesterone receptor positive, and negative for HER2, is called ER+/PR+/HER2- and is typically less aggressive than triple negative breast cancer (ER-/PR-/HER2-), which is generally more aggressive and metastasizes readily. A biomarker for aggressive breast cancer could help in early detection and identification of invasive breast cancer, leading to better patient treatment and prognosis. The purpose of this study was to determine whether a correlation exists between patient serum, circulating cytokine levels measured by enzyme-linked immunosorbent assay (ELISA), and metastatic breast cancer patient status. Positive correlations would implicate inflammatory cytokines as potential diagnostic and therapeutic targets.