Objective: Platelet-to-lymphocyte ratio (PLR), known as a key systemic inflammatory parameter, has been proved to be associated with response to neoadjuvant therapy in breast cancer (BC); however, the results remain controversial. This meta-analysis was carried out to evaluate the prognostic values of PLR in patients with BC treated with neoadjuvant chemotherapy (NACT).

Design: Meta-analysis.

Data sources: Relevant literature published on the following databases: PubMed, Embase, Web of Science databases and the Cochrane Library.

Eligibility criteria: All studies involving patients with BC treated with NACT and peripheral blood pretreatment PLR recorded were included.

Data extraction and synthesis: Two researchers independently extracted and evaluated HR/OR and its 95% CI of survival outcomes, pathological complete response (pCR) rate and clinicopathological parameters.

Results: The last search was updated to 31 December 2022. A total of 22 studies with 5533 patients with BC treated with NACT were enrolled in the final meta-analysis. Our results demonstrate that elevated PLR value appears to correlate with low pCR rate (HR 0.77, 95% CI 0.67 to 0.88, p<0.001, I²=75.80%, P_h<0.001) and poor prognosis, including overall survival (OS) (HR 1.90, 95% CI 1.39 to 2.59, p<0.001; I²=7.40%, P_h=0.365) and disease-free survival (HR 1.97, 95% CI 1.56 to 2.50, p<0.001; I²=0.0%, P_h=0.460). Furthermore, PLR level was associated with age (OR 0.86, 95% CI 0.79 to 0.93, p<0.001, I²=40.60%, P_h=0.096), menopausal status (OR 0.83, 95% CI 0.76 to 0.90, p<0.001, I²=50.80%, P_h=0.087) and T stage (OR 1.05, 95% CI 1.00 to 1.11, p=0.035; I²=70.30%, P_h=0.005) of patients with BC.

Conclusions: This meta-analysis demonstrated that high PLR was significantly related to the low pCR rate, poor OS and disease-free survival (DFS) of patients with BC treated with NACT. Therefore, PLR can be used as a potential predictor biomarker for the efficacy of NACT in BC.