Neoadjuvant chemotherapy (NAC) is a standard treatment strategy for patients with locally advanced
breast cancer (LABC). However, there are no established predictors of chemosensitivity and survival in LABC patients who undergo NAC. Many studies have demonstrated that exosomes and
cytokines are important players in intercellular communication between
tumors and their environments, and are involved in
chemotherapy resistance. Recently, it was reported that
cytokines can be packaged into exosomes, but whether exosomal
cytokines serve as
biomarkers in
breast cancer patients is still unclear. In this study, we examined the roles of
cytokines in both serum and exosomes as prognostic
biomarkers for long-term outcomes in patients with
breast cancer who undergo NAC. We isolated exosomes from the blood of 129 patients with early
breast cancer who were receiving
neoadjuvant chemotherapy between 2008 and 2011 at Samsung Medical Center. The levels of
cytokines and
growth factors in serum and exosomes were measured with ProcartaPlex immune-related panels. We investigated correlations between clinic-pathologic variables and patient survival, and Cox proportional hazards regression analysis was performed for prognostic evaluation. We detected significant differences in expression patterns between serum
cytokines and exosomal
cytokines. In both serum and exosomes, many
cytokines were positively correlated with age. In univariate analysis, patients with high serum IP-10, serum MMP-1, and exosomal
NGF had shorter overall survival. Exosomal
NGF showed significantly poorer overall survival in multivariate analysis. These findings suggest that exosomal
NGF is useful for identifying patients with poor survival outcomes.