Baseline neutrophil‑to‑lymphocyte ratio is not associated with chemotherapy‑induced nausea and vomiting in patients with breast cancer: A single‑center retrospective cohort study

Chemotherapy‑induced nausea and vomiting (CINV) remains one of the most distressing adverse effects of highly emetogenic chemotherapy despite advances in antiemetic prophylaxis. Systemic inflammatory markers have previously been investigated as potential predictors of treatment‑associated toxicities in oncology. The present study aimed to evaluate the association between baseline neutrophil‑to‑lymphocyte ratio (NLR) and the risk of CINV in patients with breast cancer receiving anthracycline‑based chemotherapy. The present retrospective cohort included 280 female patients with histologically determined breast cancer who received anthracycline and cyclophosphamide chemotherapy at a single tertiary oncology center. Baseline neutrophil and lymphocyte counts obtained prior to chemotherapy initiation were used to calculate the NLR. Patients were categorized into two groups according to NLR values: Low NLR (<3) and high NLR (≥3). The primary endpoint was complete response (CR), defined as the absence of vomiting and no need for rescue antiemetic therapy. CR rates were evaluated in the acute (0‑24 h), delayed (24‑120 h) and overall (0‑120 h) phases following chemotherapy. Associations between NLR and clinical outcomes were assessed using χ² tests and multivariate logistic regression analyses adjusting for age, menopausal status, motion sickness history, antiemetic regimen and treatment setting. Among the 280 patients included in the present analysis, 162 (57.9%) exhibited low NLR and 118 (42.1%) exhibited high NLR. Baseline demographic and clinical characteristics were comparable between the two groups. CR rates did not differ significantly between patients with low and high NLR in the overall phase (75.3 vs. 70.3%; P=0.429), acute phase (87.7 vs. 86.4%; P=0.905) or delayed phase (82.1 vs. 76.3%; P=0.296). In multivariate logistic regression analyses, NLR was found not to be an independent predictor of CINV outcomes. However, a history of motion sickness and the type of antiemetic regimen were notably associated with the likelihood of failure to achieve CR, particularly in the overall and delayed phases. Baseline NLR was found not to be independently associated with the risk of CINV in patients with breast cancer receiving highly emetogenic chemotherapy. Overall, patient‑associated susceptibility factors and antiemetic regimen selection appear to have a greater influence on CINV control compared with systemic inflammatory status as measured by NLR. Further prospective studies are warranted to explore the potential role of inflammatory biomarkers in predicting CINV.