Abstract:Objective To investigate the associations of preoperative lymphocyte-to-monocyte ratio (LMR) with clinicopathological characteristics and prognosis of breast cancer. Methods A retrospective analysis was performed on the clinical data of 135 invasive breast cancer patients treated in the Second Hospital of Jilin University from January 1, 2013 to December 31, 2017. According to the cut-off value of LMR in the ROC curve analysis, the patients were divided into high LMR group (LMR＞5.45) and low LMR group (LMR ≤5.45). Kaplan-Meier survival analysis was used to compare 3 years-disease-free survival (DFS) between two groups. Cox multifactor regression analysis was performed to identify independent prognostic factors for invasive breast cancer. Results The optimal cut-off value of LMR for predicting DFS was 5.45. The sensitivity was 85.7%, and the specificity was 45.5% as Jorden index was at 0.312. There was no significant difference in age, estrogen receptor (ER), progesterone receptor(PR), human epidermal growth factor receptor-2(HER2), Ki-67 and lymph node status between two groups (P>0.05). Univariate analysis showed that LMR ≤5.45, HER2 positivity and≥4 lymph node metastases were the risk factors influencing 3 years-DFS of invasive breast cancer（P<0.05）. Cox multifactorial analysis showed that LMR and lymph node metastases were the independent factors affecting the prognosis of invasive breast cancer（P<0.05）. Conclusion In the patients with invasive breast cancer, preoperative low LMR in peripheral blood is an independent risk factor for poor prognosis. LMR is positively correlated with prognosis and can be used as an indicator to assess prognosis. Preoperative LMR is not related with clinicopathological features of invasive breast cancer.