Prognostic and predictive significance of neutrophil/lymphocyte ratio for trastuzumab treatment efficacy in HER2-positive breast cancer.

The baseline neutrophil-to-lymphocyte ratio (NLR) has been linked to HER2-positive breast cancer (BC) prognosis treated with trastuzumab in previous reports. Here, the prognostic and predictive utility of baseline NLR in relation to trastuzumab efficacy was further assessed, with extended follow-up of up to 120 months. Clinical data from 843 patients with HER2-positive BC treated between 2013 and 2018 were analyzed. To reduce potential bias, inverse probability of treatment weighting was utilized for balancing baseline features. Patients were categorized into two groups: those who received trastuzumab and those who did not receive trastuzumab. Each group was subsequently stratified according to the median baseline NLR. Associations between NLR, clinicopathological features, and survival outcomes were investigated using univariate and multivariate analyses. Over the 50-month median follow-up (range, 6-120 months), patients receiving trastuzumab and having low baseline NLR demonstrated significantly higher disease-free survival (DFS) relative to those with a high baseline NLR (5-year DFS rate: 93.02% vs. 81.53%, P < 0.001). In comparison, baseline NLR did not influence DFS among patients who did not receive trastuzumab. Multivariate analysis confirmed that baseline NLR was indpendently predictive of DFS in trastuzumab-treated HER2-positive BC patients (high vs. low, HR = 3.61, 95% CI = 2.02-6.47, P < 0.001). Low baseline NLR was strongly linked to longer DFS in patients with HER2-positive BC undergoing trastuzumab therapy, reinforcing findings from earlier reports. Routine measurement of baseline NLR may serve as a simple and cost-effective tool to help identify cases likely to benefit from trastuzumab treatment.