Impact of changes in serum lactate dehydrogenase levels on pathological response after neoadjuvant chemotherapy in patients with breast cancer

Purpose Serum lactate dehydrogenase (LDH) level is a biomarker associated with the prognosis of breast cancer (BC) patients. However, there are no data on serum LDH levels as a dynamic marker in patients undergoing neoadjuvant chemotherapy (NAC) for BC. In the present study, we compared serum LDH levels at different periods during NAC. We related them to clinicopathologic characteristics and pathologic complete response (pCR) rates in patients with BC. Patients and methods We retrospectively analyzed the clinicopathological data and pCR rates of 691 non-metastatic BC patients from the Harbin Medical University Cancer Hospital from January 1, 2013, to December 31, 2019. Categorical data were compared using the chi-square test and Fisher's exact test for multivariate data using Logistic regression models. Any predictor variable with P < 0.05 in the univariate analysis was included in the multivariate regression analysis to study the relationship between different serum LDH level groups and pCR. Results A total of 557 patients were included in the cohort for the analysis. Before BC patients underwent NAC, a total of 510 (91.6%) patients had serum LDH levels below 230 U/L, and after completing half of the chemotherapy cycles, the number of patients with high expression of serum LDH levels gradually increased to about 37.7%. At the end of the complete cycle of chemotherapy for routine preoperative examination, 246 (44.2%) BC patients were in a state of high serum LDH expression. Patients with high expression of serum LDH levels were more likely to achieve pCR. Serum LDH levels in mid-NAC, clinical T-stage, and human epidermal growth factor receptor-2 (HER-2) expression were independent predictors of achieving pCR in patients with BC ( P < 0.05). Conclusion Our findings suggest that serum LDH level is an essential predictor of chemotherapeutic efficacy in BC patients, and we need to pay more attention to this biomarker to individualize treatment, which will help us to treat BC better and provide new targets and blueprints for our clinical treatment.