Prognostic impact of tumor-associated neutrophils in breast cancer

Objectives: Neutrophils are the most common type of leukocyte in mammals and play an essential role in the innate immune system and anti -cancer responses. However, recent studies identified the presence of tumorassociated neutrophils (TANs) as a poor prognostic factor. The present study investigated whether relationships exist between TANs and the clinicopathological factors and genetic status of breast cancer. Methods: A total of 196 breast cancer patients with sufficient biopsy, breast -conserving surgery, or mastectomy specimens between 2014 and 2021 in Hokuto Hospital were included. Results: TANs were individually counted in the tumor stroma (TS) and tumor nest (TN). A higher density of TANs in both TS and TN correlated with tumor size (TS P = 0.010; TN P = 0.001), a high histological grade (TS P < 0.001; TN P < 0.001), the histological type (TS P = 0.009; TN P = 0.034), a high ratio of lymph node metastasis (TS P < 0.001; TN P < 0.001), an advanced stage of cancer (TS P < 0.001; TN P = 0.002), intrinsic subtypes (TS P < 0.001; TN P < 0.001), ERBB2 (TS P < 0.001; TN P < 0.001), MAP3K1 (TS P = 0.002; TN P = 0.023), and TP53 (TS P < 0.001; TN P < 0.001). A higher density of TANs in TS and TN also correlated with shorter disease -free survival and overall survival (P < 0.001). Conclusion: The present results suggest that a higher density of TANs correlates with unfavorable prognostic factors in breast cancer. Further research on clinicopathological and genetic factors associated with TANs in breast cancer is needed.