Increased Percentage of mo-MDSCs in Human Peripheral Blood May Be a Potential Indicator in the Diagnosis of Breast Cancer

<b><i>Background:</i></b> Myeloid-derived suppressor cells (MDSCs) are heterogeneous cell groups that suppress T-cell responses in cancer patients and animal models. The objective of this study was to explore and evaluate the applicability of monocytic MDSCs (mo-MDSCs) in diagnosing breast cancer (BC). <b><i>Methods:</i></b> In this study, we analyzed the percentage of mo-MDSCs in freshly isolated peripheral blood of patients with BC or benign tumors (BT) of the breast and healthy donors by flow cytometry. <b><i>Results:</i></b> We found the percentage of mo-MDSCs to be 2.60 ± 0.95% in healthy donors, 2.94 ± 0.82% in BT patients, and 3.89 ± 1.35% in BC patients. The percentage of circulating mo-MDSCs was significantly increased in BC patients, and this was positively correlated with clinical stage. Receiver operating characteristic curve analysis showed 80.5% sensitivity, 61.3% specificity, and a 76.6% area under the curve, suggesting a medium clinical application value of mo-MDSCs in the diagnosis of BC. <b><i>Conclusion:</i></b> Our results suggested that the percentage of circulating mo-MDSCs in human peripheral blood may be a potential indicator in the auxiliary diagnosis of BC.