Markers with inflammatory properties, such as the ratio of neutrophils to lymphocytes and the platelet-to-lymphocyte ratio (PLR), have been documented as potential indicators for predicting pathologic complete response (pCR) following neoadjuvant chemotherapy (NACT) in cases of breast cancer. However, whether early changes of PLR (ΔPLR) during NACT can predict pCR has not been reported. A total of 257 breast cancer patients who underwent NACT were retrospectively analyzed. PLR was calculated by evaluating the complete blood cell counts prior to NACT and following two cycles of NACT. The analysis focused on the association between changes in PLR and the response to chemotherapy, as well as the association with pCR. Patients who stayed in or changed to the low PLR level subgroup after two cycles of NACT exhibited a superior response to chemotherapy, in contrast to those who stayed in or changed to the high PLR level subgroup. Of the 257 patients, 75 (29.1%) achieved a pCR after NACT. In the multivariate analysis, there was a significant association between ΔPLR and pCR, whereas pre-treatment and post-treatment PLR did not show any significant association. In multivariate analysis, patients who had a ΔPLR <0 had a notably higher rate of pCR compared with patients with a ΔPLR ≥0. It was concluded that ΔPLR, rather than pre-treatment or post-treatment PLR, is associated with pCR. This suggested that the early changes of PLR after two cycles of NACT might serve as a more accurate predictor for chemotherapy response and pCR in breast cancer.Copyright: © Dan et al.