Assessment of the role of neutrophil-lymphocyte ratio as a prognostic biomarker in breast cancer patients: a cross-sectional study

Background: Peripheral blood neutrophil–lymphocyte ratio (NLR) has been reported to predict the effects of surgery and chemotherapy in breast cancer patients. However, majority of the studies performed only one-time evaluation before commencement of treatment, while few evaluated the ratio over a period of time. In this study, we calculated NLR before surgery and postoperative adjuvant chemotherapy for patients with resectable breast cancer who underwent surgery as the initial treatment, and examined its correlation with clinicopathological factors and prognosis. Methods A total of 1095 patients with primary resectable breast cancer underwent curative resection as the first line of treatment between December 2007 and October 2018. Of these 1095 patients, 178 were included in this study. Peripheral blood was collected before, and after the surgery. Preoperative NLR was evaluated during the first hospital visit before biopsy. Postoperative NLR was evaluated using peripheral blood collected immediately prior to postoperative adjuvant chemotherapy. The cut-off values of NLR were set to 3, which has been reported to be the most commonly used value. Results Examination of postoperative NLR and prognosis in 24 breast cancer patients with higher pre-NLR revealed no significant difference (disease-free survival [DFS], p = 0.320; overall survival [OS], p = 0.409, log-rank test). However, when post-NLR and prognosis were examined in 154 breast cancer patients with lower pre-NLR, the lower post-NLR group showed significant prolongation in DFS (p < 0.001, log-rank test). Furthermore, OS tended to be prolonged in the lower post-NLR group (p = 0.056, log-rank test). Multivariate analysis of DFS in 154 breast cancer patients with lower pre-NLR showed that large tumors (hazard ratio [HR]: 4.132, p = 0.009), nuclear grade 3 (HR: 2.746, p = 0.043), and higher post-NLR (HR: 4.639, p = 0.003) were independent factors. Conclusions This study suggests that prognosis of breast cancer patients can be predicted by evaluating the NLR over time.