Purpose: We investigated the treatment response and prognosis using the neutrophil-tolymphocyte ratio (NLR) and standardized uptake value (SUV) of 18F-fluorodeoxyglucose positron emission tomography ( 18F-FDG PET) in neoadjuvant settings. Methods: Baseline NLR and maximum SUV (SUVmax ) were retrospectively analyzed in 273 females with breast cancer who received neoadjuvant chemotherapy followed by surgery.Of these, 101 patients underwent 18F-FDG PET after 3–4 neoadjuvant chemotherapy cycles, which allowed the measurement of ΔSUVmax , an early reduction in SUVmax . NLR and early SUVmax reduction (ΔSUVmax) were classified as low and high, respectively, relative to the median values. Results: The mean NLR was lower, and the mean ΔSUVmax was higher in patients with pathologic complete response (pCR) than in those with residual tumors. The ΔSUVmax was an independent variable associated with pCR. Furthermore, the high NLR group had poor recurrence-free survival (RFS) and overall survival. Among patients with ΔSUVmax data, high NLR (adjusted hazard ratio, 2.82; 95% confidence intervals [CI], 1.26–6.28; P = 0.016) and low ΔSUVmax (adjusted hazard ratio, 2.39; 95% CI, 1.07–5.34; P = 0.037) were independent prognostic factors for poor RFS. The categorization of the patients into four groups according to the combination of NLR and ΔSUVmax showed that patients with high NLR and low ΔSUVmax had significantly poorer RFS. Conclusion Baseline NLR and ΔSUVmax were significantly associated with the prognosis of patients with breast cancer who received neoadjuvant chemotherapy. These results suggest that metabolic non-responders with defective immune systems have worse survival outcomes.